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Assorted tweaks for the DeskPro 386 ROM

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This commit is contained in:
Jeff Parsons 2015-03-26 12:13:16 -07:00 • committed by jeffpar
commit 0cbae3ea11
6 changed files with 75 additions and 12 deletions
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14
modules/pcjs/lib/x86seg.js
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@ -121,11 +121,10 @@ X86Seg.ID = {
*/
X86Seg.loadReal = function loadReal(sel, fSuppress)
{
this.cpu.assert(!(sel & ~0xffff));
this.sel = sel;
this.sel = sel & 0xffff;
this.dataSize = this.addrSize = 2;
this.dataMask = this.addrMask = 0xffff;
return this.base = sel << 4;
return this.base = this.sel << 4;
};
/**
@ -157,7 +156,7 @@ X86Seg.loadProt = function loadProt(sel, fSuppress)
var addrDTLimit;
var cpu = this.cpu;
this.cpu.assert(!(sel & ~0xffff));
sel &= 0xffff;
if (!(sel & X86.SEL.LDT)) {
addrDT = cpu.addrGDT;
@ -205,7 +204,12 @@ X86Seg.loadProt = function loadProt(sel, fSuppress)
X86Seg.loadIDTReal = function loadIDTReal(nIDT)
{
var cpu = this.cpu;
cpu.assert(nIDT >= 0 && nIDT < 256 && !cpu.addrIDT && cpu.addrIDTLimit == 0x03FF);
/*
* NOTE: The Compaq DeskPro 386 ROM loads the IDTR for the real-mode IDT with a limit of 0xffff instead
* of the normal 0x3ff. A limit higher than 0x3ff is OK, since all real-mode IDT entries are 4 bytes, and
* there's no way to issue an interrupt with a vector > 0xff. Just something to be aware of.
*/
cpu.assert(nIDT >= 0 && nIDT < 256 && !cpu.addrIDT && cpu.addrIDTLimit >= 0x3ff);
/*
* Intel documentation for INT/INTO under "REAL ADDRESS MODE EXCEPTIONS" says:
*