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BIOS: Unmap some mem if less than 640KB then subtract 16KB from total in Tandy mode

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Jonathan Campbell
2021-03-23 19:13:14 -07:00
parent 6928bd885c
commit a9b38827d8
1 changed files with 7 additions and 10 deletions
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17
src/ints/bios.cpp
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@@ -9326,16 +9326,6 @@ public:
* converting KB to paragraphs. Note that it calls INT 12h while in CGA mode, and subtracts 16KB
* knowing video memory will extend downward 16KB into a 32KB region when it switches into the
* Tandy/PCjr 16-color mode. */
if (t_conv > 640) t_conv = 640;
if (ulimit > 640) ulimit = 640;
t_conv -= 16;
ulimit -= 16;
/* FIXME: INT 10h emulation currently points video RAM at 9800:0000 regardless of
* the amount of conventional memory, which happens to work as long as the
* game or application only writes to segment B800:0000. The system RAM
* backing the video ram is invisible because it's beyond the available
* conventional memory reported to the guest and therefore not mapped. */
}
else if (machine == MCH_PCJR) {
/* PCjr also shares video/system memory, but the video memory can only exist
@@ -9352,6 +9342,13 @@ public:
if (start < end) MEM_ResetPageHandler_Unmapped(start,end-start);
}
if (machine == MCH_TANDY) {
if (t_conv > 640) t_conv = 640;
if (ulimit > 640) ulimit = 640;
t_conv -= 16;
ulimit -= 16;
}
/* INT 4B. Now we can safely signal error instead of printing "Invalid interrupt 4B"
* whenever we install Windows 95. Note that Windows 95 would call INT 4Bh because
* that is where the Virtual DMA API lies in relation to EMM386.EXE */