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Akamaki
2025-02-18 22:46:18 +09:00
parent 5314f519ad
commit 2c78e7bb2f
4 changed files with 23 additions and 7 deletions
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6
src/video/vid_svga.c
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@@ -512,9 +512,9 @@ svga_in(uint16_t addr, void *priv)
/*
The IBM PS/55 Display Adapter has own Monitor Type Detection bit in the different I/O port (I/O 3E0h, 3E1h).
When the monitor cable is connected to the Display Adapter, the port 3C2h returns the value as 'no cable connection'.
The POST of PS/55 has an extra code that tries detecting the monitor on the planar VGA.
If it fails, then the POST reads the NVRAM set by the reference diskette, and writes the BIOS Data Area (Mem 487h, 489h).
MONCHK.EXE in the reference diskette uses both I/O ports to determine the monitor type, and writes the BDA.
The POST of PS/55 has an extra code. If the monitor is not detected on the planar VGA,
it reads the POS data in NVRAM set by the reference diskette, and writes the BIOS Data Area (Mem 487h, 489h).
MONCHK.EXE in the reference diskette uses both I/O ports to determine the monitor type, updates the NVRAM and BDA.
*/
if (svga->vgapal[0].r >= 10 || svga->vgapal[0].g >= 10 || svga->vgapal[0].b >= 10)
ret = 0;