Retro/pcjs
Watch
1
0
Fork
You've already forked pcjs
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Getting ready to retire old 16-bit flags code

Browse source
This commit is contained in:
Jeff Parsons 2015-03-16 14:39:03 -07:00 • committed by jeffpar
commit 72cf8d1f4d
12 changed files with 4078 additions and 3318 deletions
Download patch file Download diff file Expand all files Collapse all files

11
modules/pcjs/lib/ram.js
View file

@ -244,8 +244,8 @@ 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. This
* second chunk of RAM must have an ID of "ramCPQ".
* remainder (768Kb, 512Kb, or 384Kb) accessible only at addresses 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.
* Presumably, the other configurations (256Kb and 512Kb) would leave 768Kb and 512Kb accessible at
@ -253,8 +253,11 @@ 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. The second
* register is a read-only diagnostics register that indicates jumper configuration and parity errors.
* any ROMs in the range 0x000E0000-0x000FFFFF, and optionally write-protecting that 128Kb; internally,
* this register corresponds to bMapping.
*
* The second register is a read-only diagnostics register that indicates jumper configuration and
* parity errors; internally, this register corresponds to bSettings.
*
* To emulate the memory-mapped registers at 0x80C00000, the RAM component allocates a block at that
* address using this custom controller once it sees an allocation for "ramCPQ".