cpuops.js

/**
 * @fileoverview Implements PDP-11 opcode handlers.
 * @author <a href="mailto:Jeff@pcjs.org">Jeff Parsons</a>
 * @copyright © 2012-2020 Jeff Parsons
 *
 * This file is part of PCjs, a computer emulation software project at <https://www.pcjs.org>.
 *
 * It has been adapted from the JavaScript PDP 11/70 Emulator written by Paul Nankervis
 * (paulnank@hotmail.com) at <http://skn.noip.me/pdp11/pdp11.html>.  This code may be used
 * freely provided the original authors are acknowledged in any modified source code.
 *
 * PCjs is free software: you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * PCjs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with PCjs.  If not,
 * see <http://www.gnu.org/licenses/gpl.html>.
 *
 * You are required to include the above copyright notice in every modified copy of this work
 * and to display that copyright notice when the software starts running; see COPYRIGHT in
 * <https://www.pcjs.org/modules/shared/lib/defines.js>.
 *
 * Some PCjs files also attempt to load external resource files, such as character-image files,
 * ROM files, and disk image files. Those external resource files are not considered part of PCjs
 * for purposes of the GNU General Public License, and the author does not claim any copyright
 * as to their contents.
 */

"use strict";

if (typeof module !== "undefined") {
    var PDP11 = require("./defines");
}

/*
 * Decoding starts near the bottom of this file, in op1120() and op1140().  Obviously, there are
 * MANY more PDP-11 models than the 11/20 and 11/40, but for the broad model categories that PDPjs
 * supports (ie, MODEL_1120, MODEL_1140, MODEL_1145, and MODEL_1170), the biggest differences are
 * between MODEL_1120 and MODEL_1140, so decoding is divided into those two categories, and all
 * other differences are handled inside the opcode handlers.
 *
 * The basic decoding approach is to dispatch on the top 4 bits of the opcode, and if further
 * decoding is required, the dispatched function will dispatch on the next 4 bits, and so on
 * (although some of the intermediate levels dispatch only on 2 bits, which could also be handled
 * with a switch statement).
 *
 * Eventually, every opcode should end up either in an opXXX() function or opUndefined().  For
 * opcodes that perform a simple read or write operation, the entire operation is handled by
 * the opXXX() function.  For opcodes that perform a more extensive read/modify/write operation
 * (also known as an update operation), those opXXX() functions usually rely on a corresponding
 * fnXXX() helper function.
 *
 * For example, opADD() passes the helper function fnADD() to the appropriate update method.  This
 * allows the update method to perform the entire read/modify/write operation, because the modify
 * step is performed internally, via the fnXXX() helper function.
 *
 * For the handful of instructions in the 1140 tables that actually exist only on the 11/45 and
 * 11/70 (ie, MFPD, MTPD, and SPL), those opcode handlers perform their own model checks.  That's
 * simpler than creating additional tables, and seems fine for instructions that are not commonly
 * executed.
 */

/**
 * fnADD(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (dst + src)
 */
PDP11.fnADD = function(src, dst)
{
    var result = dst + src;
    this.updateAddFlags(result, src, dst);
    return result & 0xffff;
};

/**
 * fnADDB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (dst + src)
 */
PDP11.fnADDB = function(src, dst)
{
    var result = dst + src;
    this.updateAddFlags(result << 8, src << 8, dst << 8);
    return result & 0xff;
};

/**
 * fnASL(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst << 1)
 */
PDP11.fnASL = function(src, dst)
{
    var result = dst << 1;
    this.updateShiftFlags(result);
    return result & 0xffff;
};

/**
 * fnASLB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst << 1)
 */
PDP11.fnASLB = function(src, dst)
{
    var result = dst << 1;
    this.updateShiftFlags(result << 8);
    return result & 0xff;
};

/**
 * fnASR(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst >> 1)
 */
PDP11.fnASR = function(src, dst)
{
    var result = (dst & 0x8000) | (dst >> 1) | (dst << 16);
    this.updateShiftFlags(result);
    return result & 0xffff;
};

/**
 * fnASRB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst >> 1)
 */
PDP11.fnASRB = function(src, dst)
{
    var result = (dst & 0x80) | (dst >> 1) | (dst << 8);
    this.updateShiftFlags(result << 8);
    return result & 0xff;
};

/**
 * fnBIC(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (~src & dst)
 */
PDP11.fnBIC = function(src, dst)
{
    var result = dst & ~src;
    this.updateNZVFlags(result);
    return result;
};

/**
 * fnBICB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (~src & dst)
 */
PDP11.fnBICB = function(src, dst)
{
    var result = dst & ~src;
    this.updateNZVFlags(result << 8);
    return result;
};

/**
 * fnBIS(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (dst | src)
 */
PDP11.fnBIS = function(src, dst)
{
    var result = dst | src;
    this.updateNZVFlags(result);
    return result;
};

/**
 * fnBISB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (dst | src)
 */
PDP11.fnBISB = function(src, dst)
{
    var result = dst | src;
    this.updateNZVFlags(result << 8);
    return result;
};

/**
 * fnCOM(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (~dst)
 */
PDP11.fnCOM = function(src, dst)
{
    var result = ~dst | 0x10000;
    this.updateAllFlags(result);
    return result & 0xffff;
};

/**
 * fnCOMB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (~dst)
 */
PDP11.fnCOMB = function(src, dst)
{
    var result = ~dst | 0x100;
    this.updateAllFlags(result << 8);
    return result & 0xff;
};

/**
 * fnDEC(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ie, 1)
 * @param {number} dst
 * @return {number} (dst - src)
 */
PDP11.fnDEC = function(src, dst)
{
    var result = dst - src;
    this.updateDecFlags(result, dst);
    return result & 0xffff;
};

/**
 * fnDECB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ie, 1)
 * @param {number} dst
 * @return {number} (dst - src)
 */
PDP11.fnDECB = function(src, dst)
{
    var result = dst - src;
    this.updateDecFlags(result << 8, dst << 8);
    return result & 0xff;
};

/**
 * fnINC(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ie, 1)
 * @param {number} dst
 * @return {number} (dst + src)
 */
PDP11.fnINC = function(src, dst)
{
    var result = dst + src;
    this.updateIncFlags(result, dst);
    return result & 0xffff;
};

/**
 * fnINCB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ie, 1)
 * @param {number} dst
 * @return {number} (dst + src)
 */
PDP11.fnINCB = function(src, dst)
{
    var result = dst + src;
    this.updateIncFlags(result << 8, dst << 8);
    return result & 0xff;
};

/**
 * fnNEG(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (-dst)
 */
PDP11.fnNEG = function(src, dst)
{
    var result = -dst;
    /*
     * If the sign bit of both dst and result are set, the original value must have been 0x8000, triggering overflow.
     */
    this.updateAllFlags(result, result & dst & 0x8000);
    return result & 0xffff;
};

/**
 * fnNEGB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (-dst)
 */
PDP11.fnNEGB = function(src, dst)
{
    var result = -dst;
    /*
     * If the sign bit of both dst and result are set, the original value must have been 0x80, which triggers overflow.
     */
    this.updateAllFlags(result << 8, (result & dst & 0x80) << 8);
    return result & 0xff;
};

/**
 * fnROL(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst >> 1)
 */
PDP11.fnROL = function(src, dst)
{
    var result = (dst << 1) | ((this.flagC >> 16) & 1);
    this.updateShiftFlags(result);
    return result & 0xffff;
};

/**
 * fnROLB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst >> 1)
 */
PDP11.fnROLB = function(src, dst)
{
    var result = (dst << 1) | ((this.flagC >> 16) & 1);
    this.updateShiftFlags(result << 8);
    return result & 0xff;
};

/**
 * fnROR(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst >> 1)
 */
PDP11.fnROR = function(src, dst)
{
    var result = (((this.flagC & 0x10000) | dst) >> 1) | (dst << 16);
    this.updateShiftFlags(result);
    return result & 0xffff;
};

/**
 * fnRORB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst >> 1)
 */
PDP11.fnRORB = function(src, dst)
{
    var result = ((((this.flagC & 0x10000) >> 8) | dst) >> 1) | (dst << 8);
    this.updateShiftFlags(result << 8);
    return result & 0xff;
};

/**
 * fnSUB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (dst - src)
 */
PDP11.fnSUB = function(src, dst)
{
    var result = dst - src;
    this.updateSubFlags(result, src, dst);
    return result & 0xffff;
};

/**
 * fnSUBB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (dst - src)
 */
PDP11.fnSUBB = function(src, dst)
{
    var result = dst - src;
    this.updateSubFlags(result << 8, src << 8, dst << 8);
    return result & 0xff;
};

/**
 * fnSWAB(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src (ignored)
 * @param {number} dst
 * @return {number} (dst with bytes swapped)
 */
PDP11.fnSWAB = function(src, dst)
{
    var result = (dst << 8) | (dst >> 8);
    /*
     * N and Z are based on the low byte of the result, which is the same as the high byte of dst.
     */
    this.updateNZVCFlags(dst & 0xff00);
    return result & 0xffff;
};

/**
 * fnXOR(src, dst)
 *
 * @this {CPUStatePDP11}
 * @param {number} src
 * @param {number} dst
 * @return {number} (dst ^ src)
 */
PDP11.fnXOR = function(src, dst)
{
    var result = dst ^ src;
    this.updateNZVFlags(result);
    return result & 0xffff;
};

/**
 * opADC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opADC = function(opCode)
{
    this.updateDstWord(opCode, this.getCF()? 1 : 0, PDP11.fnADD);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opADCB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opADCB = function(opCode)
{
    this.updateDstByte(opCode, this.getCF()? 1 : 0, PDP11.fnADDB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opADD(opCode)
 *
 * From the PDP-11/20 Processor HandBook (1971), p. 61:
 *
 *     Add src,dst (06SSDD)
 *
 *     Operation:
 *          (dst) = (src) + (dst)
 *
 *     Condition Codes:
 *          N: set if result < 0; cleared otherwise
 *          Z: set if result = 0; cleared otherwise
 *          V: set if there was arithmetic overflow as a result of the operation, that is both operands
 *             were of the same sign and the result was of the opposite sign; cleared otherwise
 *          C: set if there was a carry from the most significant bit of the result; cleared otherwise
 *
 *     Description:
 *          Adds the source operand to the destination operand and stores the result at the destination address.
 *          The original contents of the destination are lost. The contents of the source are not affected.
 *          Two's complement addition is performed.
 *
 *     Examples:
 *          Add to register:            ADD 20,R0
 *          Add to memory:              ADD R1,XXX
 *          Add register to register:   ADD R1,R2
 *          Add memory to memory:       ADD @#17750,XXX
 *
 *          XXX is a programmer-defined mnemonic for a memory location.
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opADD = function(opCode)
{
    this.updateDstWord(opCode, this.readSrcWord(opCode), PDP11.fnADD);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 2) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opASH(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opASH = function(opCode)
{
    var src = this.readDstWord(opCode);
    var reg = (opCode >> 6) & 7;
    var result = this.regsGen[reg];
    if (result & 0x8000) result |= 0xffff0000;
    this.flagC = this.flagV = 0;
    src &= 0x3F;
    if (src & 0x20) {
        src = 64 - src;         // shift right
        if (src > 16) src = 16;
        this.flagC = result << (17 - src);
        result = result >> src;
    } else if (src) {
        if (src > 16) {         // shift left
            this.flagV = result;
            result = 0;
        } else {
            result = result << src;
            this.flagC = result;
            var dst = (result >> 15) & 0xffff;  // check successive sign bits
            if (dst && dst !== 0xffff) this.flagV = 0x8000;
        }
    }
    this.regsGen[reg] = result & 0xffff;
    this.flagN = this.flagZ = result;
    this.nStepCycles -= (this.dstMode? (5 + 1) : (6 + 1)) + src;
};

/**
 * opASHC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opASHC = function(opCode)
{
    var src = this.readDstWord(opCode);
    var reg = (opCode >> 6) & 7;
    var dst = (this.regsGen[reg] << 16) | this.regsGen[reg | 1];
    this.flagC = this.flagV = 0;
    src &= 0x3F;
    if (src & 0x20) {
        src = 64 - src;         // shift right
        if (src > 32) src = 32;
        var result = dst >> (src - 1);
        this.flagC = result << 16;
        result >>= 1;
        if (dst & 0x80000000) result |= 0xffffffff << (32 - src);
    } else {
        if (src) {              // shift left
            result = dst << (src - 1);
            this.flagC = result >> 15;
            result <<= 1;
            if (src > 32) src = 32;
            dst = dst >> (32 - src);
            if (dst) {
                dst |= (0xffffffff << src) & 0xffffffff;
                if (dst !== 0xffffffff) this.flagV = 0x8000;
            }
        } else {
            result = dst;
        }
    }
    this.regsGen[reg] = (result >> 16) & 0xffff;
    this.regsGen[reg | 1] = result & 0xffff;
    this.flagN = result >> 16;
    this.flagZ = result >> 16 | result;
    this.nStepCycles -= (this.dstMode? (5 + 1) : (6 + 1)) + src;
};

/**
 * opASL(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opASL = function(opCode)
{
    this.updateDstWord(opCode, 0, PDP11.fnASL);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opASLB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opASLB = function(opCode)
{
    this.updateDstByte(opCode, 0, PDP11.fnASLB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opASR(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opASR = function(opCode)
{
    this.updateDstWord(opCode, 0, PDP11.fnASR);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opASRB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opASRB = function(opCode)
{
    this.updateDstByte(opCode, 0, PDP11.fnASRB);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.dstAddr & 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opBCC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBCC = function(opCode)
{
    this.branch(opCode, !this.getCF());
};

/**
 * opBCS(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBCS = function(opCode)
{
    this.branch(opCode, this.getCF());
};

/**
 * opBIC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBIC = function(opCode)
{
    this.updateDstWord(opCode, this.readSrcWord(opCode), PDP11.fnBIC);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 2) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opBICB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBICB = function(opCode)
{
    this.updateDstByte(opCode, this.readSrcByte(opCode), PDP11.fnBICB);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 2) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opBIS(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBIS = function(opCode)
{
    this.updateDstWord(opCode, this.readSrcWord(opCode), PDP11.fnBIS);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 2) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opBISB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBISB = function(opCode)
{
    this.updateDstByte(opCode, this.readSrcByte(opCode), PDP11.fnBISB);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 2) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opBIT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBIT = function(opCode)
{
    var src = this.readSrcWord(opCode);
    var dst = this.readDstWord(opCode);
    this.updateNZVFlags((src < 0? this.regsGen[-src-1] : src) & dst);
    this.nStepCycles -= (this.dstMode? (3 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 1) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opBITB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBITB = function(opCode)
{
    var src = this.readSrcByte(opCode);
    var dst = this.readDstByte(opCode);
    this.updateNZVFlags(((src < 0? (this.regsGen[-src-1] & 0xff) : src) & dst) << 8);
    this.nStepCycles -= (this.dstMode? (3 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 1) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opBEQ(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBEQ = function(opCode)
{
    this.branch(opCode, this.getZF());
};

/**
 * opBGE(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBGE = function(opCode)
{
    this.branch(opCode, !this.getNF() == !this.getVF());
};

/**
 * opBGT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBGT = function(opCode)
{
    this.branch(opCode, !this.getZF() && (!this.getNF() == !this.getVF()));
};

/**
 * opBHI(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBHI = function(opCode)
{
    this.branch(opCode, !this.getCF() && !this.getZF());
};

/**
 * opBLE(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBLE = function(opCode)
{
    this.branch(opCode, this.getZF() || (!this.getNF() != !this.getVF()));
};

/**
 * opBLOS(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBLOS = function(opCode)
{
    this.branch(opCode, this.getCF() || this.getZF());
};

/**
 * opBLT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBLT = function(opCode)
{
    this.branch(opCode, !this.getNF() != !this.getVF());
};

/**
 * opBMI(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBMI = function(opCode)
{
    this.branch(opCode, this.getNF());
};

/**
 * opBNE(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBNE = function(opCode)
{
    this.branch(opCode, !this.getZF());
};

/**
 * opBPL(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBPL = function(opCode)
{
    this.branch(opCode, !this.getNF());
};

/**
 * opBPT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBPT = function(opCode)
{
    this.trap(PDP11.TRAP.BPT, 0, PDP11.REASON.OPCODE);
};

/**
 * opBR(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBR = function(opCode)
{
    this.branch(opCode, true);
};

/**
 * opBVC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBVC = function(opCode)
{
    this.branch(opCode, !this.getVF());
};

/**
 * opBVS(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opBVS = function(opCode)
{
    this.branch(opCode, this.getVF());
};

/**
 * opCLR(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCLR = function(opCode)
{
    this.writeDstWord(opCode, 0, this.updateAllFlags);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opCLRB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCLRB = function(opCode)
{
    this.writeDstByte(opCode, 0, PDP11.WRITE.BYTE, this.updateAllFlags);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opCLC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCLC = function(opCode)
{
    this.clearCF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opCLN(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCLN = function(opCode)
{
    this.clearNF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opCLV(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCLV = function(opCode)
{
    this.clearVF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opCLZ(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCLZ = function(opCode)
{
    this.clearZF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opCLx(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCLx = function(opCode)
{
    if (opCode & 0x1) this.clearCF();
    if (opCode & 0x2) this.clearVF();
    if (opCode & 0x4) this.clearZF();
    if (opCode & 0x8) this.clearNF();
    /*
     * TODO: Review whether this class of undocumented instructions really has a constant cycle time.
     */
    this.nStepCycles -= (4 + 1);
};

/**
 * opCMP(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCMP = function(opCode)
{
    var src = this.readSrcWord(opCode);
    var dst = this.readDstWord(opCode);
    var result = (src = (src < 0? this.regsGen[-src-1] : src)) - dst;
    /*
     * NOTE: CMP calculates (src - dst) rather than (dst - src), so src and dst updateSubFlags() parms must be reversed.
     */
    this.updateSubFlags(result, dst, src);
    this.nStepCycles -= (this.dstMode? (3 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 1) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opCMPB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCMPB = function(opCode)
{
    var src = this.readSrcByte(opCode);
    var dst = this.readDstByte(opCode);
    var result = (src = (src < 0? (this.regsGen[-src-1] & 0xff): src) << 8) - (dst <<= 8);
    /*
     * NOTE: CMP calculates (src - dst) rather than (dst - src), so src and dst updateSubFlags() parms must be reversed.
     */
    this.updateSubFlags(result, dst, src);
    this.nStepCycles -= (this.dstMode? (3 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 1) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opCOM(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCOM = function(opCode)
{
    this.updateDstWord(opCode, 0, PDP11.fnCOM);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opCOMB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opCOMB = function(opCode)
{
    this.updateDstByte(opCode, 0, PDP11.fnCOMB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opDEC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opDEC = function(opCode)
{
    this.updateDstWord(opCode, 1, PDP11.fnDEC);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opDECB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opDECB = function(opCode)
{
    this.updateDstByte(opCode, 1, PDP11.fnDECB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opDIV(opCode)
 *
 * The instruction "DIV SRC,Rn" determines SRC using the DSTMODE portion of the opcode and Rn using
 * the SRCMODE portion; Rn can only be a register (and it should be an EVEN-numbered register, lest you
 * get unexpected results).  The dividend (DST) is then calculated as:
 *
 *      DST = (regs[Rn] << 16) | (regs[Rn|1])
 *
 * DST is divided by SRC, and the quotient is stored in regs[Rn] and the remainder in regs[Rn|1].
 *
 * For example:
 *
 *      DIV     R4,R0
 *
 * where R4 = 006400 and R0,R1 = 000000,015000 will result in R0,R1 = 000002,000000.
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opDIV = function(opCode)
{
    /*
     * TODO: Review and determine if flag updates can be encapsulated in an updateDivFlags() function.
     */
    var src = this.readDstWord(opCode);
    if (!src) {
        this.flagN = 0;         // NZVC
        this.flagZ = 0;
        this.flagV = 0x8000;
        this.flagC = 0x10000;   // divide by zero
        this.nStepCycles -= (6 + 1);
    } else {
        var reg = (opCode >> 6) & 7;
        var dst = (this.regsGen[reg] << 16) | this.regsGen[reg | 1];
        this.flagC = this.flagV = 0;
        if (src & 0x8000) src |= ~0xffff;
        var result = ~~(dst / src);
        if (result >= -32768 && result <= 32767) {
            this.regsGen[reg] = result & 0xffff;
            this.regsGen[reg | 1] = (dst - (result * src)) & 0xffff;
            this.flagZ = (result >> 16) | result;
            this.flagN = result >> 16;
        } else {
            this.flagV = 0x8000;                                // overflow - following are indeterminate
            this.flagZ = (result >> 15) | result;               // dodgy
            this.flagN = dst >> 16;                             // just as dodgy
            if (src === -1 && this.regsGen[reg] === 0xfffe) {
                this.regsGen[reg] = this.regsGen[reg | 1] = 1;  // etc
            }
        }
        this.nStepCycles -= (52 + 1);                           // 52 is the average of the shortest and longest times
    }
};

/**
 * opEMT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opEMT = function(opCode)
{
    this.trap(PDP11.TRAP.EMT, 0, PDP11.REASON.OPCODE);
    this.nStepCycles -= (22 + 3 - 5);
};

/**
 * opHALT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opHALT = function(opCode)
{
    if (this.regPSW & PDP11.PSW.CMODE) {
        this.regErr |= PDP11.CPUERR.BADHALT;
        this.trap(PDP11.TRAP.BUS, 0, PDP11.REASON.HALT);
    } else {
        if (this.panel) {
            /*
             * The PDP-11/20 Handbook (1971) says that HALT does the following:
             *
             *      Causes the processor operation to cease. The console is given control of the bus.
             *      The console data lights display the contents of RO; the console address lights display
             *      the address after the halt instruction. Transfers on the UNIBUS are terminated immediately.
             *      The PC points to the next instruction to be executed. Pressing the continue key on the
             *      console causes processor operation to resume. No INIT signal is given.
             *
             * However, the PDP-11/70 Handbook (1979) suggests some slight differences:
             *
             *      Causes the processor operation to cease. The console is given control of the processor.
             *      The data lights display the contents of the PC (which is the address of the HALT instruction
             *      plus 2). Transfers on the UNIBUS are terminated immediately. Pressing the continue key on
             *      the console causes processor operation to resume.
             *
             * Given that the 11/70 doesn't saying anything about displaying R0 on a HALT, and also given that
             * the 11/70 CPU EXERCISER diagnostic writes a value to the Console Switch/Display Register immediately
             * before HALT'ing, I'm going to assume that updating the data display with R0 is unique to the 11/20.
             *
             * Also, I'm a little suspicious of the 11/70 comment that the "data lights display the contents of
             * the PC," since previous models display the PC on the ADDRESS lights, not the DATA lights.  And as
             * I already explained, doing anything to the data lights at this point would undo what the 11/70
             * diagnostics do.
             */
            if (this.model == PDP11.MODEL_1120) {
                this.panel.setData(this.regsGen[0], true);
            }
        }
        if (!this.dbg) {
            /*
             * This will leave the PC exactly where it's supposed to be: at the address of the HALT + 2.
             */
            this.stopCPU();
        } else {
            /*
             * When the Debugger is present, this call will rewind PC by 2 so that the HALT instruction is
             * displayed, making it clear why the processor stopped; the user could also use the "dh" command
             * to dump the Debugger's instruction history buffer to see why it stopped, assuming the history
             * buffer is enabled, but that's more work.
             *
             * Because rewinding is not normal CPU behavior, attempting to Run again (or use the Debugger's
             * "g" command) would cause an immediate HALT again -- except that checkInstruction() checks for that
             * precise condition, so if the CPU starts on a HALT, checkInstruction() will skip over it.
             */
            this.dbg.stopInstruction();
        }
    }
    this.nStepCycles -= 7;
};

/**
 * opINC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opINC = function(opCode)
{
    this.updateDstWord(opCode, 1, PDP11.fnINC);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opINCB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opINCB = function(opCode)
{
    this.updateDstByte(opCode, 1, PDP11.fnINCB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opIOT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opIOT = function(opCode)
{
    this.trap(PDP11.TRAP.IOT, 0, PDP11.REASON.OPCODE);
    this.nStepCycles -= (22 + 3 - 5);
};

PDP11.JMP_CYCLES = [
    0, 6 + 1, 6 + 1, 8 + 2, 6 + 1, 9 + 2, 7 + 2, 10 + 3
];

/**
 * opJMP(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opJMP = function(opCode)
{
    /*
     * Since JMP and JSR opcodes have their own unique timings for the various dst modes, we must snapshot
     * nStepCycles before decoding the mode, and then use that to update nStepCycles.
     */
    this.nSnapCycles = this.nStepCycles;
    this.setPC(this.readDstAddr(opCode));
    this.nStepCycles = this.nSnapCycles - PDP11.JMP_CYCLES[this.dstMode];
};

PDP11.JSR_CYCLES = [
    0, 13 + 1, 13 + 1, 15 + 2, 13 + 1, 16 + 2, 14 + 2, 17 + 3
];

/**
 * opJSR(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opJSR = function(opCode)
{
    /*
     * Since JMP and JSR opcodes have their own unique timings for the various dst modes, we must
     * snapshot nStepCycles before decoding the mode, and then use that to update nStepCycles.
     */
    this.nSnapCycles = this.nStepCycles;
    var addr = this.readDstAddr(opCode);
    /*
     * As per the WARNING in readSrcWord(), reading the SRC register AFTER decoding the DST operand
     * is entirely appropriate.
     */
    var reg = (opCode >> PDP11.SRCMODE.SHIFT) & PDP11.OPREG.MASK;
    this.pushWord(this.regsGen[reg]);
    this.regsGen[reg] = this.getPC();
    this.setPC(addr);
    this.nStepCycles = this.nSnapCycles - PDP11.JSR_CYCLES[this.dstMode];
};

/**
 * opMARK(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMARK = function(opCode)
{
    var addr = (this.getPC() + ((opCode & 0x3F) << 1)) & 0xffff;
    var src = this.readWord(addr | this.addrDSpace);
    this.setPC(this.regsGen[5]);
    this.setSP(addr + 2);
    this.regsGen[5] = src;
    this.nStepCycles -= (6 + 2);
};

/**
 * opMFPD(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMFPD = function(opCode)
{
    var data = this.readWordFromPrevSpace(opCode, PDP11.ACCESS.DSPACE);
    this.updateNZVFlags(data);
    this.pushWord(data);
    this.nStepCycles -= (10 + 1);
};

/**
 * opMFPI(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMFPI = function(opCode)
{
    var data = this.readWordFromPrevSpace(opCode, PDP11.ACCESS.ISPACE);
    this.updateNZVFlags(data);
    this.pushWord(data);
    this.nStepCycles -= (10 + 1);
};

/**
 * opMFPS(opCode)
 *
 *      1067XX  MFPS - Move Byte From PSW
 *
 *      The 8-bit contents of the PS are moved to the effective destination.  If destination is mode 0,
 *      PS bit 7 is sign extended through the upper byte of the register.  The destination operand is treated
 *      as a byte address.  11/34A only.
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMFPS = function(opCode)
{
    PDP11.opUndefined.call(this, opCode);
};

/**
 * opMFPT(opCode)
 *
 *      000007  MFPT - Move From Processor Type
 *
 *      Loads R0 with a value indicating the processor type.
 *
 *      R0  Hardware
 *       1  PDP-11/44
 *       3  PDP-11/24 (should be 2)
 *       3  PDP-11/23
 *       4  SBC-11/21
 *       5  All J11 chips including 11/73, 11/83, 11/93
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMFPT = function(opCode)
{
    PDP11.opUndefined.call(this, opCode);
};

PDP11.MOV_CYCLES = [
    2 + 1, 8 + 1, 8 + 1, 11 + 2, 9 + 1, 12 + 2, 10 + 2, 13 + 3,
    3 + 1, 8 + 1, 8 + 1, 11 + 2, 9 + 1, 12 + 2, 11 + 2, 14 + 3
];

/**
 * opMOV(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMOV = function(opCode)
{
    /*
     * Since MOV opcodes have their own unique timings for the various dst modes, we must snapshot
     * nStepCycles after decoding the src mode, and then use that to update nStepCycles.
     */
    var data = this.readSrcWord(opCode);
    this.nSnapCycles = this.nStepCycles;
    this.writeDstWord(opCode, data, this.updateNZVFlags);
    this.nStepCycles = this.nSnapCycles - PDP11.MOV_CYCLES[(this.srcMode? 8 : 0) + this.dstMode] + (this.dstReg == 7 && !this.dstMode? 2 : 0);
};

/**
 * opMOVB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMOVB = function(opCode)
{
    var data = this.readSrcByte(opCode);
    this.writeDstByte(opCode, data, PDP11.WRITE.SBYTE, this.updateNZVFlags);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 2) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

PDP11.MTP_CYCLES = [
    6 + 1, 11 + 2, 11 + 2, 14 + 3, 12 + 2, 15 + 3, 14 + 3, 17 + 4
];

/**
 * opMTPD(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMTPD = function(opCode)
{
    /*
     * Since MTPD and MTPI opcodes have their own unique timings for the various dst modes, we must snapshot
     * nStepCycles before decoding the mode, and then use that to update nStepCycles.
     */
    var data = this.popWord();
    this.nSnapCycles = this.nStepCycles;
    this.updateNZVFlags(data);
    this.writeWordToPrevSpace(opCode, PDP11.ACCESS.DSPACE, data);
    this.nStepCycles = this.nSnapCycles - PDP11.MTP_CYCLES[this.dstMode];
};

/**
 * opMTPI(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMTPI = function(opCode)
{
    /*
     * Since MTPD and MTPI opcodes have their own unique timings for the various dst modes, we must snapshot
     * nStepCycles before decoding the mode, and then use that to update nStepCycles.
     */
    var data = this.popWord();
    this.nSnapCycles = this.nStepCycles;
    this.updateNZVFlags(data);
    this.writeWordToPrevSpace(opCode, PDP11.ACCESS.ISPACE, data);
    this.nStepCycles = this.nSnapCycles - PDP11.MTP_CYCLES[this.dstMode];
};

/**
 * opMTPS(opCode)
 *
 *      1064XX  MTPS - Move Byte To PSW
 *
 *      The 8 bits of the effective operand replace the current contents of the PS <0:7>.  The source operand
 *      address is treated as a byte address.  Note that PS bit 4 cannot be set with this instruction.  The
 *      src operand remains unchanged.  11/34A only.
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMTPS = function(opCode)
{
    PDP11.opUndefined.call(this, opCode);
};

/**
 * opMUL(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opMUL = function(opCode)
{
    var src = this.readDstWord(opCode);
    var reg = (opCode >> 6) & 7;
    var dst = this.regsGen[reg];
    var result = ((src << 16) >> 16) * ((dst << 16) >> 16);
    this.regsGen[reg] = (result >> 16) & 0xffff;
    this.regsGen[reg | 1] = result & 0xffff;
    this.updateMulFlags(result|0);
    this.nStepCycles -= (22 + 1);
};

/**
 * opNEG(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opNEG = function(opCode)
{
    this.updateDstWord(opCode, 0, PDP11.fnNEG);
    this.nStepCycles -= (this.dstMode? (10 + 1) : (5 + 1));
};

/**
 * opNEGB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opNEGB = function(opCode)
{
    this.updateDstByte(opCode, 0, PDP11.fnNEGB);
    this.nStepCycles -= (this.dstMode? (10 + 1) : (5 + 1));
};

/**
 * opNOP(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opNOP = function(opCode)
{
    this.nStepCycles -= (4 + 1);        // TODO: Review (this is just a guess based on CLC)
};

/**
 * opRESET(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opRESET = function(opCode)
{
    if (!(this.regPSW & PDP11.PSW.CMODE)) {
        this.resetCPU();

        if (this.panel) {
            /*
             * The PDP-11/70 XXDP test "EKBBF0" reports the following, with PANEL messages on ("m panel on"):
             *
             *      CNSW.writeWord(177570,000101) @033502
             *      CNSW.readWord(177570): 000000 @032114
             *      LOOK AT THE CONSOLE LIGHTS
             *      THE DATA LIGHTS SHOULD READ 166667
             *      THE ADDRESS LIGHTS SHOULD READ  CNSW.readWord(177570): 000000 @032150
             *      032236
             *      CHANGE SWITCH 7 TO CONTINUE
             *      CNSW.readWord(177570): 000000 @032236
             *      stopped (31518011 instructions, 358048873 cycles, 58644 ms, 6105465 hz)
             *      R0=166667 R1=002362 R2=000000 R3=000000 R4=000000 R5=026642
             *      SP=001074 PC=032236 PS=000344 SR=00000000 T0 N0 Z1 V0 C0
             *      032236: 032737 000200 177570   BIT   #200,@#177570
             *      >> tr
             *      CNSW.readWord(177570): 000000 @032236 (cpu halted)
             *      R0=166667 R1=002362 R2=000000 R3=000000 R4=000000 R5=026642
             *      SP=001074 PC=032244 PS=000344 SR=00000000 T0 N0 Z1 V0 C0
             *      032244: 001773                 BEQ   032234                 ;cycles=0
             *      >> tr
             *      R0=166667 R1=002362 R2=000000 R3=000000 R4=000000 R5=026642
             *      SP=001074 PC=032234 PS=000344 SR=00000000 T0 N0 Z1 V0 C0
             *      032234: 000005                 RESET                        ;cycles=5
             *
             * It's a little hard to see why the DATA lights should read 166667, since the PANEL messages indicate
             * that the last CNSW.writeWord(177570) was for 000101, not 166667.  So I'm guessing that the RESET
             * instruction is supposed to propagate R0 to the console's DISPLAY register.
             *
             * This is similar to what we do for the HALT instruction (but only if this.model == PDP11.MODEL_1120).
             * These Console features do not seem to be very well documented, assuming they exist.
             *
             * UPDATE: This behavior appears to be confirmed by remarks in the PDP-11/20 Processor Handbook (1971),
             * p. 141:
             *
             *      HALT - displays processor register R0 when bus control is transferred to console during a HALT
             *      instruction.
             *
             *      RESET - displays register R0 for during [duration?] of RESET (70 msec).
             *
             * I haven't found similar remarks in the PDP-11/70 Processor Handbooks, so I'm not sure if that's an
             * oversight or if 11/70 panels are slightly different in this regard.  It's also not clear what they meant
             * by "for duration of RESET".  Is something supposed to happen to the DATA lights after the RESET is done?
             */
            this.panel.setData(this.regsGen[0], true);
        }
    }
    this.nStepCycles -= 667;            // TODO: Review (but it's definitely a big number)
};

/**
 * opROL(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opROL = function(opCode)
{
    this.updateDstWord(opCode, 0, PDP11.fnROL);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opROLB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opROLB = function(opCode)
{
    this.updateDstByte(opCode, 0, PDP11.fnROLB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opROR(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opROR = function(opCode)
{
    this.updateDstWord(opCode, 0, PDP11.fnROR);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opRORB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opRORB = function(opCode)
{
    this.updateDstByte(opCode, 0, PDP11.fnRORB);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.dstAddr & 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opRTI(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opRTI = function(opCode)
{
    this.trapReturn();
    /*
     * Unlike RTT, RTI permits an immediate trace, which we resolve by propagating PSW.TF to OPFLAG.TRAP_TF
     * (which, as written below, requires that both flags have the same bit value; see defines.js).
     *
     * NOTE: This RTI trace behavior is NEW for machines that have both RTI and RTT.  Early models didn't have RTT,
     * so the old RTI behaved exactly like the new RTT.  Which is why the 11/20 jump table below calls opRTT() instead
     * of opRTI() for RTI.
     */
    this.opFlags |= (this.regPSW & PDP11.PSW.TF);
    this.nStepCycles -= (10 + 3);
};

/**
 * opRTS(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opRTS = function(opCode)
{
    if (opCode & 0x08) {
        PDP11.opUndefined.call(this, opCode);
        return;
    }
    var src = this.popWord();
    var reg = opCode & PDP11.OPREG.MASK;
    /*
     * When the popular "RTS PC" form is used, we might as well eliminate the useless setting of PC...
     */
    if (reg == PDP11.REG.PC) {
        this.setPC(src);
    } else {
        this.setPC(this.regsGen[reg]);
        this.regsGen[reg] = src;
    }
    this.nStepCycles -= (7 + 2);
};

/**
 * opRTT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opRTT = function(opCode)
{
    this.trapReturn();
    this.nStepCycles -= (10 + 3);
};

/**
 * opSBC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSBC = function(opCode)
{
    this.updateDstWord(opCode, this.getCF()? 1 : 0, PDP11.fnSUB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opSBCB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSBCB = function(opCode)
{
    this.updateDstByte(opCode, this.getCF()? 1 : 0, PDP11.fnSUBB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opSEC(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSEC = function(opCode)
{
    this.setCF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opSEN(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSEN = function(opCode)
{
    this.setNF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opSEV(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSEV = function(opCode)
{
    this.setVF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opSEZ(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSEZ = function(opCode)
{
    this.setZF();
    this.nStepCycles -= (4 + 1);
};

/**
 * opSEx(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSEx = function(opCode)
{
    if (opCode & 0x1) this.setCF();
    if (opCode & 0x2) this.setVF();
    if (opCode & 0x4) this.setZF();
    if (opCode & 0x8) this.setNF();
    /*
     * TODO: Review whether this class of undocumented instructions really has a constant cycle time.
     */
    this.nStepCycles -= (4 + 1);
};

/**
 * opSOB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode (077Rnn)
 */
PDP11.opSOB = function(opCode)
{
    var reg = (opCode & PDP11.SRCMODE.REG) >> PDP11.SRCMODE.SHIFT;
    if ((this.regsGen[reg] = ((this.regsGen[reg] - 1) & 0xffff))) {
        this.setPC(this.getPC() - ((opCode & PDP11.DSTMODE.MASK) << 1));
        this.nStepCycles += 1;          // unlike normal branches, taking this branch is actually 1 cycle faster
    }
    this.nStepCycles -= (5 + 1);
};

/**
 * opSPL(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSPL = function(opCode)
{
    if (!(opCode & 0x08) || this.model < PDP11.MODEL_1145) {
        PDP11.opUndefined.call(this, opCode);
        return;
    }
    if (!(this.regPSW & PDP11.PSW.CMODE)) {
        this.regPSW = (this.regPSW & ~PDP11.PSW.PRI) | ((opCode & 0x7) << PDP11.PSW.SHIFT.PRI);
        this.opFlags |= PDP11.OPFLAG.IRQ_DELAY;
        this.opFlags &= ~PDP11.OPFLAG.IRQ;
    }
    this.nStepCycles -= (4 + 1);
};

/**
 * opSUB(opCode)
 *
 * From the PDP-11/20 Processor HandBook (1971), p. 62:
 *
 *     Subtract src,dst (16SSDD)
 *
 *     Operation:
 *          (dst) = (dst) - (src) [in detail, (dst) + ~(src) + 1 (dst)]
 *
 *     Condition Codes:
 *          N: set if result < 0; cleared otherwise
 *          Z: set if result = 0; cleared otherwise
 *          V: set if there was arithmetic overflow as a result of the operation, that is if operands were of
 *             opposite signs and the sign of the source was the same as the sign of the result; cleared otherwise
 *          C: cleared if there was a carry from the most significant bit of the result; set otherwise
 *
 *     Description:
 *          Subtracts the source operand from the destination operand and leaves the result at the destination address.
 *          The orignial [sic] contents of the destination are lost. The contents of the source are not affected.
 *          In double-precision arithmetic the C-bit, when set, indicates a "borrow".
 *
 *     Example:
 *                  SUB R1,R2
 *
 *              BEFORE          AFTER
 *          (R1) = 011111   (R2) = 012345
 *          (R1) = 011111   (R2) = 001234
 *
 *              NZVC            NZVC
 *              1111            0001
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSUB = function(opCode)
{
    this.updateDstWord(opCode, this.readSrcWord(opCode), PDP11.fnSUB);
    this.nStepCycles -= (this.dstMode? (8 + 1) + (this.srcReg && this.dstReg >= 6? 1 : 0) : (this.srcMode? (3 + 2) : (2 + 1)) + (this.dstReg == 7? 2 : 0));
};

/**
 * opSWAB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSWAB = function(opCode)
{
    this.updateDstWord(opCode, 0, PDP11.fnSWAB);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opSXT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opSXT = function(opCode)
{
    this.writeDstWord(opCode, this.getNF()? 0xffff : 0, this.updateNZVFlags);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opTRAP(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opTRAP = function(opCode)
{
    this.trap(PDP11.TRAP.TRAP, 0, PDP11.REASON.OPCODE);
};

/**
 * opTST(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opTST = function(opCode)
{
    var result = this.readDstWord(opCode);
    this.assert(!(result & ~0xffff));   // assert that C flag will be clear
    this.updateAllFlags(result);
    this.nStepCycles -= (this.dstMode? (3 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opTSTB(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opTSTB = function(opCode)
{
    var result = this.readDstByte(opCode);
    this.assert(!(result & ~0xff));     // assert that C flag will be clear
    this.updateAllFlags(result << 8);
    this.nStepCycles -= (this.dstMode? (3 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opWAIT(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opWAIT = function(opCode)
{
    /*
     * The original PDP-11 emulation code would actually stop emulating instructions now, relying on assorted
     * setTimeout() callbacks, setInterval() callbacks, device XHR (XMLHttpRequest) callbacks, etc, to eventually
     * call interrupt(), which would then transition the CPU out of its "wait" state and kickstart emulate() again.
     *
     * That approach isn't compatible with PCjs emulators, which prefer to rely on the simulated CPU clock to
     * drive all simulated device updates.  This means components should call the CPU's setTimer() function, which
     * invokes the provided callback when the number of CPU cycles that correspond to the requested number of
     * milliseconds have elapsed.  This also gives us the ability to scale device response times as needed if the
     * user decides to crank up CPU speed, and to freeze them along with the CPU whenever the user halts the machine.
     *
     * However, the PCjs approach requires the CPU to continue running.  One simple solution to this dilemma:
     *
     *      1) opWAIT() sets a new opFlags bit (OPFLAG.WAIT)
     *      2) Rewind the PC back to the WAIT instruction
     *      3) Whenever stepCPU() detects OPFLAG.WAIT, call checkInterrupts()
     *      4) If checkInterrupts() detects an interrupt, advance PC past the WAIT and then dispatch the interrupt
     *
     * Technically, the PC is already exactly where it's supposed to be, so why are we wasting time with steps
     * 2 and 4?  It's largely for the Debugger's sake, so that as long as execution is "blocked" by a WAIT, that's
     * what you'll see in the Debugger.  I could make those steps conditioned on the presence of the Debugger,
     * but I feel it's better to keep all code paths the same.
     *
     * NOTE: It's almost always a bad idea to add more checks to the inner stepCPU() loop, because every additional
     * check can have a measurable (negative) impact on performance.  Which is why it's important to use opFlags bits
     * whenever possible, since we can test for multiple (up to 32) exceptional conditions with a single check.
     *
     * We also used to update the machine's display(s) whenever transitioning to the WAIT state.  However, that
     * caused this instruction to generate enormous overhead, and it's no longer necessary, since we now rely on
     * a timer (the PDP-11's own KW11 60Hz Line Clock timer, to be precise) to generate periodic display updates.
     *
     *      if (!(this.opFlags & PDP11.OPFLAG.WAIT) && this.cmp) this.cmp.updateDisplays();
     *
     * Finally, it's been noted several places online that the WAIT instruction puts the contents of R0 into the
     * Front Panel's "DATA PATH" (and possibly even directly into the "DISPLAY REGISTER", making the DATASEL switch
     * setting irrelevant).  I can't find any supporting DEC documentation regarding this, but for now, we'll go
     * with popular lore and propagate R0 to the panel's "active" data register.
     */
    if (this.panel) {
        this.panel.setAddr(this.regsGen[7], true);
        this.panel.setData(this.regsGen[0], true);
    }
    this.opFlags |= PDP11.OPFLAG.WAIT;
    this.advancePC(-2);
    this.nStepCycles -= 3;
};

/**
 * opXOR(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opXOR = function(opCode)
{
    var reg = (opCode >> PDP11.SRCMODE.SHIFT) & PDP11.OPREG.MASK;
    this.updateDstWord(opCode, this.regsGen[reg + this.offRegSrc], PDP11.fnXOR);
    this.nStepCycles -= (this.dstMode? (8 + 1) : (2 + 1) + (this.dstReg == 7? 2 : 0));
};

/**
 * opUndefined(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.opUndefined = function(opCode)
{
    if (DEBUGGER && this.dbg) {
        if (this.dbg.undefinedInstruction(opCode)) return;
    }
    this.trap(PDP11.TRAP.RESERVED, 0, PDP11.REASON.OPCODE);
};

/**
 * op1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op1120 = function(opCode)
{
    PDP11.aOpXnnn_1120[opCode >> 12].call(this, opCode);
};

/**
 * op0Xnn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op0Xnn_1120 = function(opCode)
{
    PDP11.aOp0Xnn_1120[(opCode >> 8) & 0xf].call(this, opCode);
};

/**
 * op0AXn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op0AXn_1120 = function(opCode)
{
    PDP11.aOp0AXn_1120[(opCode >> 6) & 0x3].call(this, opCode);
};

/**
 * op0BXn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op0BXn_1120 = function(opCode)
{
    PDP11.aOp0BXn_1120[(opCode >> 6) & 0x3].call(this, opCode);
};

/**
 * op0CXn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op0CXn_1120 = function(opCode)
{
    PDP11.aOp0CXn_1120[(opCode >> 6) & 0x3].call(this, opCode);
};

/**
 * op00Xn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op00Xn_1120 = function(opCode)
{
    PDP11.aOp00Xn_1120[(opCode >> 4) & 0xf].call(this, opCode);
};

/**
 * op00AX_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op00AX_1120 = function(opCode)
{
    PDP11.aOp00AX_1120[opCode & 0xf].call(this, opCode);
};

/**
 * op00BX_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op00BX_1120 = function(opCode)
{
    PDP11.aOp00BX_1120[opCode & 0xf].call(this, opCode);
};

/**
 * op000X_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op000X_1120 = function(opCode)
{
    PDP11.aOp000X_1120[opCode & 0xf].call(this, opCode);
};

/**
 * op8Xnn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op8Xnn_1120 = function(opCode)
{
    PDP11.aOp8Xnn_1120[(opCode >> 8) & 0xf].call(this, opCode);
};

/**
 * op8AXn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op8AXn_1120 = function(opCode)
{
    PDP11.aOp8AXn_1120[(opCode >> 6) & 0x3].call(this, opCode);
};

/**
 * op8BXn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op8BXn_1120 = function(opCode)
{
    PDP11.aOp8BXn_1120[(opCode >> 6) & 0x3].call(this, opCode);
};

/**
 * op8CXn_1120(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op8CXn_1120 = function(opCode)
{
    PDP11.aOp8CXn_1120[(opCode >> 6) & 0x3].call(this, opCode);
};

PDP11.aOpXnnn_1120 = [
    PDP11.op0Xnn_1120,          // 0x0nnn
    PDP11.opMOV,                // 0x1nnn   01SSDD          11/20+  2.3
    PDP11.opCMP,                // 0x2nnn   02SSDD          11/20+  2.3*
    PDP11.opBIT,                // 0x3nnn   03SSDD          11/20+  2.9*
    PDP11.opBIC,                // 0x4nnn   04SSDD          11/20+  2.9
    PDP11.opBIS,                // 0x5nnn   05SSDD          11/20+  2.3
    PDP11.opADD,                // 0x6nnn   06SSDD          11/20+  2.3
    PDP11.opUndefined,          // 0x7nnn
    PDP11.op8Xnn_1120,          // 0x8nnn
    PDP11.opMOVB,               // 0x9nnn   11SSDD          11/20+  2.3
    PDP11.opCMPB,               // 0xAnnn   12SSDD          11/20+  2.3
    PDP11.opBITB,               // 0xBnnn   13SSDD          11/20+  2.9
    PDP11.opBICB,               // 0xCnnn   14SSDD          11/20+  2.9
    PDP11.opBISB,               // 0xDnnn   15SSDD          11/20+  2.3
    PDP11.opSUB,                // 0xEnnn   16SSDD          11/20+  2.3
    PDP11.opUndefined           // 0xFnnn
];

PDP11.aOp0Xnn_1120 = [
    PDP11.op00Xn_1120,          // 0x00nn
    PDP11.opBR,                 // 0x01nn   0004XX          11/20+  2.6
    PDP11.opBNE,                // 0x02nn   0010XX          11/20+  2.6**
    PDP11.opBEQ,                // 0x03nn   0014XX          11/20+  2.6**
    PDP11.opBGE,                // 0x04nn   0020XX          11/20+  2.6**
    PDP11.opBLT,                // 0x05nn   0024XX          11/20+  2.6**
    PDP11.opBGT,                // 0x06nn   0030XX          11/20+  2.6**
    PDP11.opBLE,                // 0x07nn   0034XX          11/20+  2.6**
    PDP11.opJSR,                // 0x08nn   004RDD          11/20+  4.4
    PDP11.opJSR,                // 0x09nn   004RDD          11/20+  4.4
    PDP11.op0AXn_1120,          // 0x0Ann
    PDP11.op0BXn_1120,          // 0x0Bnn
    PDP11.op0CXn_1120,          // 0x0Cnn
    PDP11.opUndefined,          // 0x0Dnn
    PDP11.opUndefined,          // 0x0Enn
    PDP11.opUndefined           // 0x0Fnn
];

PDP11.aOp0AXn_1120 = [
    PDP11.opCLR,                // 0x0A0n   0050DD          11/20+  2.3
    PDP11.opCOM,                // 0x0A4n   0051DD          11/20+  2.3
    PDP11.opINC,                // 0x0A8n   0052DD          11/20+  2.3
    PDP11.opDEC                 // 0x0ACn   0053DD          11/20+  2.3
];

PDP11.aOp0BXn_1120 = [
    PDP11.opNEG,                // 0x0B0n   0054DD          11/20+  2.3
    PDP11.opADC,                // 0x0B4n   0055DD          11/20+  2.3
    PDP11.opSBC,                // 0x0B8n   0056DD          11/20+  2.3
    PDP11.opTST                 // 0x0BCn   0057DD          11/20+  2.3*
];

PDP11.aOp0CXn_1120 = [
    PDP11.opROR,                // 0x0C0n   0060DD          11/20+  2.3*
    PDP11.opROL,                // 0x0C4n   0061DD          11/20+  2.3*
    PDP11.opASR,                // 0x0C8n   0062DD          11/20+  2.3*
    PDP11.opASL                 // 0x0CCn   0063DD          11/20+  2.3*
];

PDP11.aOp00Xn_1120 = [
    PDP11.op000X_1120,          // 0x000n   000000-000017
    PDP11.opUndefined,          // 0x001n   000020-000037
    PDP11.opUndefined,          // 0x002n   000040-000057
    PDP11.opUndefined,          // 0x003n   000060-000077
    PDP11.opJMP,                // 0x004n   0001DD          11/20+  1.2
    PDP11.opJMP,                // 0x005n   0001DD          11/20+  1.2
    PDP11.opJMP,                // 0x006n   0001DD          11/20+  1.2
    PDP11.opJMP,                // 0x007n   0001DD          11/20+  1.2
    PDP11.opRTS,                // 0x008n   00020R          11/20+  3.5 (opRTS() will also confirm that bit 3 is clear)
    PDP11.opUndefined,          // 0x009n   00023N
    PDP11.op00AX_1120,          // 0x00An   000240-000257
    PDP11.op00BX_1120,          // 0x00Bn   000260-000277
    PDP11.opSWAB,               // 0x00Cn   0003DD          11/20+  2.3
    PDP11.opSWAB,               // 0x00Dn   0003DD          11/20+  2.3
    PDP11.opSWAB,               // 0x00En   0003DD          11/20+  2.3
    PDP11.opSWAB                // 0x00Fn   0003DD          11/20+  2.3
];

PDP11.aOp000X_1120 = [
    PDP11.opHALT,               // 0x0000   000000          11/20+  1.8
    PDP11.opWAIT,               // 0x0001   000001          11/20+  1.8
    PDP11.opRTT,                // 0x0002   000002          11/20+  4.8 (this is really RTI, but on the 11/20, it behaves like RTT)
    PDP11.opBPT,                // 0x0003
    PDP11.opIOT,                // 0x0004   000004          11/20+  9.3
    PDP11.opRESET,              // 0x0005   000005          11/20+  20ms
    PDP11.opUndefined,          // 0x0006
    PDP11.opUndefined,          // 0x0007
    PDP11.opUndefined,          // 0x0008
    PDP11.opUndefined,          // 0x0009
    PDP11.opUndefined,          // 0x000A
    PDP11.opUndefined,          // 0x000B
    PDP11.opUndefined,          // 0x000C
    PDP11.opUndefined,          // 0x000D
    PDP11.opUndefined,          // 0x000E
    PDP11.opUndefined           // 0x000F
];

PDP11.aOp00AX_1120 = [
    PDP11.opNOP,                // 0x00A0   000240          11/20+  1.5
    PDP11.opCLC,                // 0x00A1   000241          11/20+  1.5
    PDP11.opCLV,                // 0x00A2   000242          11/20+  1.5
    PDP11.opCLx,                // 0x00A3   000243          11/20+  1.5
    PDP11.opCLZ,                // 0x00A4   000244          11/20+  1.5
    PDP11.opCLx,                // 0x00A5   000245          11/20+  1.5
    PDP11.opCLx,                // 0x00A6   000246          11/20+  1.5
    PDP11.opCLx,                // 0x00A7   000247          11/20+  1.5
    PDP11.opCLN,                // 0x00A8   000250          11/20+  1.5
    PDP11.opCLx,                // 0x00A9   000251          11/20+  1.5
    PDP11.opCLx,                // 0x00AA   000252          11/20+  1.5
    PDP11.opCLx,                // 0x00AB   000253          11/20+  1.5
    PDP11.opCLx,                // 0x00AC   000254          11/20+  1.5
    PDP11.opCLx,                // 0x00AD   000255          11/20+  1.5
    PDP11.opCLx,                // 0x00AE   000256          11/20+  1.5
    PDP11.opCLx                 // 0x00AF   000257          11/20+  1.5
];

PDP11.aOp00BX_1120 = [
    PDP11.opNOP,                // 0x00B0   000260          11/20+  1.5
    PDP11.opSEC,                // 0x00B1   000261          11/20+  1.5
    PDP11.opSEV,                // 0x00B2   000262          11/20+  1.5
    PDP11.opSEx,                // 0x00B3   000263          11/20+  1.5
    PDP11.opSEZ,                // 0x00B4   000264          11/20+  1.5
    PDP11.opSEx,                // 0x00B5   000265          11/20+  1.5
    PDP11.opSEx,                // 0x00B6   000266          11/20+  1.5
    PDP11.opSEx,                // 0x00B7   000267          11/20+  1.5
    PDP11.opSEN,                // 0x00B8   000270          11/20+  1.5
    PDP11.opSEx,                // 0x00B9   000271          11/20+  1.5
    PDP11.opSEx,                // 0x00BA   000272          11/20+  1.5
    PDP11.opSEx,                // 0x00BB   000273          11/20+  1.5
    PDP11.opSEx,                // 0x00BC   000274          11/20+  1.5
    PDP11.opSEx,                // 0x00BD   000275          11/20+  1.5
    PDP11.opSEx,                // 0x00BE   000276          11/20+  1.5
    PDP11.opSEx                 // 0x00BF   000277          11/20+  1.5
];

PDP11.aOp8Xnn_1120 = [
    PDP11.opBPL,                // 0x80nn   1000XX          11/20+  2.6**
    PDP11.opBMI,                // 0x81nn   1004XX          11/20+  2.6**
    PDP11.opBHI,                // 0x82nn   1010XX          11/20+  2.6**
    PDP11.opBLOS,               // 0x83nn   1014XX          11/20+  2.6**
    PDP11.opBVC,                // 0x84nn   1020XX          11/20+  2.6**
    PDP11.opBVS,                // 0x85nn   1024XX          11/20+  2.6**
    PDP11.opBCC,                // 0x86nn   1030XX          11/20+  2.6**
    PDP11.opBCS,                // 0x87nn   1034XX          11/20+  2.6**
    PDP11.opEMT,                // 0x88nn   104000-104377   11/20+  9.3
    PDP11.opTRAP,               // 0x89nn   104400-104777   11/20+  9.3
    PDP11.op8AXn_1120,          // 0x8Ann
    PDP11.op8BXn_1120,          // 0x8Bnn
    PDP11.op8CXn_1120,          // 0x8Cnn
    PDP11.opUndefined,          // 0x8Dnn
    PDP11.opUndefined,          // 0x8Enn
    PDP11.opUndefined           // 0x8Fnn
];

PDP11.aOp8AXn_1120 = [
    PDP11.opCLRB,               // 0x8A0n   1050DD          11/20+  2.3
    PDP11.opCOMB,               // 0x8A4n   1051DD          11/20+  2.3
    PDP11.opINCB,               // 0x8A8n   1052DD          11/20+  2.3
    PDP11.opDECB                // 0x8ACn   1053DD          11/20+  2.3
];

PDP11.aOp8BXn_1120 = [
    PDP11.opNEGB,               // 0x8B0n   1054DD          11/20+  2.3
    PDP11.opADCB,               // 0x8B4n   1055DD          11/20+  2.3
    PDP11.opSBCB,               // 0x8B8n   1056DD          11/20+  2.3
    PDP11.opTSTB                // 0x8BCn   1057DD          11/20+  2.3*
];

PDP11.aOp8CXn_1120 = [
    PDP11.opRORB,               // 0x8C0n   1060DD          11/20+  2.3*
    PDP11.opROLB,               // 0x8C4n   1061DD          11/20+  2.3*
    PDP11.opASRB,               // 0x8C8n   1062DD          11/20+  2.3*
    PDP11.opASLB                // 0x8CCn   1063DD          11/20+  2.3*
];

/**
 * op1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op1140 = function(opCode)
{
    PDP11.aOpXnnn_1140[opCode >> 12].call(this, opCode);
};

/**
 * op0Xnn_1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op0Xnn_1140 = function(opCode)
{
    PDP11.aOp0Xnn_1140[(opCode >> 8) & 0xf].call(this, opCode);
};

/**
 * op0DXn_1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op0DXn_1140 = function(opCode)
{
    PDP11.aOp0DXn_1140[(opCode >> 6) & 0x3].call(this, opCode);
};

/**
 * op00Xn_1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op00Xn_1140 = function(opCode)
{
    PDP11.aOp00Xn_1140[(opCode >> 4) & 0xf].call(this, opCode);
};

/**
 * op000X_1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op000X_1140 = function(opCode)
{
    PDP11.aOp000X_1140[opCode & 0xf].call(this, opCode);
};

/**
 * op7Xnn_1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op7Xnn_1140 = function(opCode)
{
    PDP11.aOp7Xnn_1140[(opCode >> 8) & 0xf].call(this, opCode);
};

/**
 * op8Xnn_1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op8Xnn_1140 = function(opCode)
{
    PDP11.aOp8Xnn_1140[(opCode >> 8) & 0xf].call(this, opCode);
};

/**
 * op8DXn_1140(opCode)
 *
 * @this {CPUStatePDP11}
 * @param {number} opCode
 */
PDP11.op8DXn_1140 = function(opCode)
{
    if (this.model < PDP11.MODEL_1145) {
        PDP11.opUndefined.call(this, opCode);
        return;
    }
    PDP11.aOp8DXn_1140[(opCode >> 6) & 0x3].call(this, opCode);
};

PDP11.aOpXnnn_1140 = [
    PDP11.op0Xnn_1140,          // 0x0nnn
    PDP11.opMOV,                // 0x1nnn   01SSDD          11/20+  2.3
    PDP11.opCMP,                // 0x2nnn   02SSDD          11/20+  2.3*
    PDP11.opBIT,                // 0x3nnn   03SSDD          11/20+  2.9*
    PDP11.opBIC,                // 0x4nnn   04SSDD          11/20+  2.9
    PDP11.opBIS,                // 0x5nnn   05SSDD          11/20+  2.3
    PDP11.opADD,                // 0x6nnn   06SSDD          11/20+  2.3
    PDP11.op7Xnn_1140,          // 0x7nnn
    PDP11.op8Xnn_1140,          // 0x8nnn
    PDP11.opMOVB,               // 0x9nnn   11SSDD          11/20+  2.3
    PDP11.opCMPB,               // 0xAnnn   12SSDD          11/20+  2.3
    PDP11.opBITB,               // 0xBnnn   13SSDD          11/20+  2.9
    PDP11.opBICB,               // 0xCnnn   14SSDD          11/20+  2.9
    PDP11.opBISB,               // 0xDnnn   15SSDD          11/20+  2.3
    PDP11.opSUB,                // 0xEnnn   16SSDD          11/20+  2.3
    PDP11.opUndefined           // 0xFnnn
];

PDP11.aOp0Xnn_1140 = [
    PDP11.op00Xn_1140,          // 0x00nn
    PDP11.opBR,                 // 0x01nn   0004XX          11/20+  2.6
    PDP11.opBNE,                // 0x02nn   0010XX          11/20+  2.6**
    PDP11.opBEQ,                // 0x03nn   0014XX          11/20+  2.6**
    PDP11.opBGE,                // 0x04nn   0020XX          11/20+  2.6**
    PDP11.opBLT,                // 0x05nn   0024XX          11/20+  2.6**
    PDP11.opBGT,                // 0x06nn   0030XX          11/20+  2.6**
    PDP11.opBLE,                // 0x07nn   0034XX          11/20+  2.6**
    PDP11.opJSR,                // 0x08nn   004RDD          11/20+  4.4
    PDP11.opJSR,                // 0x09nn   004RDD          11/20+  4.4
    PDP11.op0AXn_1120,          // 0x0Ann
    PDP11.op0BXn_1120,          // 0x0Bnn
    PDP11.op0CXn_1120,          // 0x0Cnn
    PDP11.op0DXn_1140,          // 0x0Dnn
    PDP11.opUndefined,          // 0x0Enn
    PDP11.opUndefined           // 0x0Fnn
];

PDP11.aOp0DXn_1140 = [
    PDP11.opMARK,               // 0x0D0n                   11/40+          LEIS
    PDP11.opMFPI,               // 0x0D4n                   11/40+
    PDP11.opMTPI,               // 0x0D8n                   11/40+
    PDP11.opSXT                 // 0x0DCn                   11/40+          LEIS
];

PDP11.aOp00Xn_1140 = [
    PDP11.op000X_1140,          // 0x000n   000000-000017
    PDP11.opUndefined,          // 0x001n   000020-000037
    PDP11.opUndefined,          // 0x002n   000040-000057
    PDP11.opUndefined,          // 0x003n   000060-000077
    PDP11.opJMP,                // 0x004n   0001DD          11/20+  1.2
    PDP11.opJMP,                // 0x005n   0001DD          11/20+  1.2
    PDP11.opJMP,                // 0x006n   0001DD          11/20+  1.2
    PDP11.opJMP,                // 0x007n   0001DD          11/20+  1.2
    PDP11.opRTS,                // 0x008n   00020R          11/20+  3.5 (opRTS() will also confirm that bit 3 is clear)
    PDP11.opSPL,                // 0x009n   00023N          11/45+      (opSPL() will also confirm that bit 3 is set)
    PDP11.op00AX_1120,          // 0x00An   000240-000257
    PDP11.op00BX_1120,          // 0x00Bn   000260-000277
    PDP11.opSWAB,               // 0x00Cn   0003DD          11/20+  2.3
    PDP11.opSWAB,               // 0x00Dn   0003DD          11/20+  2.3
    PDP11.opSWAB,               // 0x00En   0003DD          11/20+  2.3
    PDP11.opSWAB                // 0x00Fn   0003DD          11/20+  2.3
];

PDP11.aOp000X_1140 = [
    PDP11.opHALT,               // 0x0000   000000          11/20+  1.8
    PDP11.opWAIT,               // 0x0001   000001          11/20+  1.8
    PDP11.opRTI,                // 0x0002   000002          11/20+  4.8
    PDP11.opBPT,                // 0x0003   000003
    PDP11.opIOT,                // 0x0004   000004          11/20+  9.3
    PDP11.opRESET,              // 0x0005   000005          11/20+  20ms
    PDP11.opRTT,                // 0x0006   000006          11/40+          LEIS
    PDP11.opMFPT,               // 0x0007   000007          11/44+
    PDP11.opUndefined,          // 0x0008
    PDP11.opUndefined,          // 0x0009
    PDP11.opUndefined,          // 0x000A
    PDP11.opUndefined,          // 0x000B
    PDP11.opUndefined,          // 0x000C
    PDP11.opUndefined,          // 0x000D
    PDP11.opUndefined,          // 0x000E
    PDP11.opUndefined           // 0x000F
];

PDP11.aOp7Xnn_1140 = [
    PDP11.opMUL,                // 0x70nn                   11/40+          EIS
    PDP11.opMUL,                // 0x71nn                   11/40+          EIS
    PDP11.opDIV,                // 0x72nn                   11/40+          EIS
    PDP11.opDIV,                // 0x73nn                   11/40+          EIS
    PDP11.opASH,                // 0x74nn                   11/40+          EIS
    PDP11.opASH,                // 0x75nn                   11/40+          EIS
    PDP11.opASHC,               // 0x76nn                   11/40+          EIS
    PDP11.opASHC,               // 0x77nn                   11/40+          EIS
    PDP11.opXOR,                // 0x78nn                   11/40+          LEIS
    PDP11.opXOR,                // 0x79nn                   11/40+          LEIS
    PDP11.opUndefined,          // 0x7Ann
    PDP11.opUndefined,          // 0x7Bnn
    PDP11.opUndefined,          // 0x7Cnn
    PDP11.opUndefined,          // 0x7Dnn
    PDP11.opSOB,                // 0x7Enn                   11/40+          LEIS
    PDP11.opSOB                 // 0x7Fnn                   11/40+          LEIS
];

PDP11.aOp8Xnn_1140 = [
    PDP11.opBPL,                // 0x80nn   1000XX          11/20+  2.6**
    PDP11.opBMI,                // 0x81nn   1004XX          11/20+  2.6**
    PDP11.opBHI,                // 0x82nn   1010XX          11/20+  2.6**
    PDP11.opBLOS,               // 0x83nn   1014XX          11/20+  2.6**
    PDP11.opBVC,                // 0x84nn   1020XX          11/20+  2.6**
    PDP11.opBVS,                // 0x85nn   1024XX          11/20+  2.6**
    PDP11.opBCC,                // 0x86nn   1030XX          11/20+  2.6**
    PDP11.opBCS,                // 0x87nn   1034XX          11/20+  2.6**
    PDP11.opEMT,                // 0x88nn   104000-104377   11/20+  9.3
    PDP11.opTRAP,               // 0x89nn   104400-104777   11/20+  9.3
    PDP11.op8AXn_1120,          // 0x8Ann   1050XX
    PDP11.op8BXn_1120,          // 0x8Bnn   1054XX
    PDP11.op8CXn_1120,          // 0x8Cnn   1060XX
    PDP11.op8DXn_1140,          // 0x8Dnn   106400-106777
    PDP11.opUndefined,          // 0x8Enn   1070XX
    PDP11.opUndefined           // 0x8Fnn   1074XX
];

PDP11.aOp8DXn_1140 = [
    PDP11.opMTPS,               // 0x8D0n   1064XX          11/34A only
    PDP11.opMFPD,               // 0x8D4n   1065XX          11/45+
    PDP11.opMTPD,               // 0x8D8n   1066XX          11/45+
    PDP11.opMFPS                // 0x8DCn   1067XX          11/34A only
];