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Support for true physical memory aliases

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This commit is contained in:
Jeff Parsons 2015-03-23 18:15:29 -07:00 • committed by jeffpar
commit 7085b72fc4
28 changed files with 2185 additions and 2047 deletions
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42
modules/pcjs/lib/ram.js
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@ -244,7 +244,7 @@ RAM.init = function()
*
* DeskPro 386 machines came with a minimum of 1Mb of RAM, which could be configured (via jumpers)
* for 256Kb, 512Kb or 640Kb of conventional memory, starting at address 0x00000000, with the
* remainder (768Kb, 512Kb, or 384Kb) accessible only at addresses just below 0x01000000. In PCjs,
* remainder (768Kb, 512Kb, or 384Kb) accessible only at an address just below 0x01000000. In PCjs,
* this second chunk of RAM must be separately allocated, with an ID of "ramCPQ".
*
* The typical configuration was 640Kb of conventional memory, leaving 384Kb accessible at 0x00FA0000.
@ -254,7 +254,7 @@ RAM.init = function()
* The DeskPro 386 also contained two memory-mapped registers at 0x80C00000. The first is a write-only
* mapping register that provides the ability to map the 128Kb at 0x00FE0000 to 0x000E0000, replacing
* any ROMs in the range 0x000E0000-0x000FFFFF, and optionally write-protecting that 128Kb; internally,
* this register corresponds to bMapping.
* this register corresponds to bMappings.
*
* The second register is a read-only diagnostics register that indicates jumper configuration and
* parity errors; internally, this register corresponds to bSettings.
@ -275,17 +275,21 @@ RAM.init = function()
function CompaqController(ram)
{
this.ram = ram;
this.bMapping = CompaqController.MAPPING.DEFAULT;
this.bMappings = CompaqController.MAPPINGS.DEFAULT;
this.bSettings = CompaqController.SETTINGS.BASE_640KB;
this.aBlocksDst = null;
}
CompaqController.ADDR = 0x80C00000;
CompaqController.ADDR = 0x80C00000;
CompaqController.MAP_SRC = 0x00FE0000;
CompaqController.MAP_DST = 0x000E0000;
CompaqController.MAP_SIZE = 0x00020000;
/*
* Bit definitions for the 8-bit write-only memory-mapping register (bMapping)
* Bit definitions for the 8-bit write-only memory-mapping register (bMappings)
*/
CompaqController.MAPPING = {
NORELOC: 0x01, // is this bit is CLEAR, the last 128Kb (at 0x00FE0000) is relocated to 0x000E0000
CompaqController.MAPPINGS = {
UNMAPPED: 0x01, // is this bit is CLEAR, the last 128Kb (at 0x00FE0000) is mapped to 0x000E0000
READWRITE: 0x02, // if this bit is CLEAR, the last 128Kb (at 0x00FE0000) is read-only (ie, write-protected)
RESERVED: 0xFC, // the remaining 6 bits are reserved and should always be SET
DEFAULT: 0xFF
@ -324,11 +328,31 @@ CompaqController.readByte = function readCompaqControllerByte(off)
*
* @this {Memory}
* @param {number} off
* @param {number} b (which should already be pre-masked to 8 bits; see Bus.prototype.setByteDirect)
* @param {number} b
*/
CompaqController.writeByte = function writeCompaqControllerByte(off, b)
{
this.controller.bMapping = b;
var aBlocks;
var controller = this.controller;
var bus = controller.bus;
if (b != controller.bMappings) {
if (!(b & CompaqController.MAPPINGS.UNMAPPED)) {
if (!controller.aBlocksDst) {
controller.aBlocksDst = bus.getMemoryBlocks(CompaqController.MAP_DST, CompaqController.MAP_SIZE);
}
aBlocks = bus.getMemoryBlocks(CompaqController.MAP_SRC, CompaqController.MAP_SIZE);
var type = (b & CompaqController.MAPPINGS.READWRITE)? Memory.TYPE.RAM : Memory.TYPE.ROM;
bus.setMemoryBlocks(CompaqController.MAP_DST, CompaqController.MAP_SIZE, aBlocks, type);
}
else {
if (controller.aBlocksDst) {
bus.setMemoryBlocks(CompaqController.MAP_DST, CompaqController.MAP_SIZE, controller.aBlocksDst);
controller.aBlocksDst = null;
}
}
controller.bMappings = b;
}
if (DEBUG) this.cpu.stopCPU();
};
CompaqController.ACCESS = [CompaqController.readByte, CompaqController.readByte, CompaqController.readByte,