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Finally, some progress with the IBM VGA ROM

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This commit is contained in:
Jeff Parsons 2015-06-02 14:09:59 -07:00
commit f7e93fbeb3
6 changed files with 574 additions and 88 deletions
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5
devices/pc/bios/compaq/deskpro386/1988-01-28/1988-01-28.nasm
View file

@ -4805,6 +4805,11 @@ xa9e9: cs rep movsw ; 0000A9E9 F32EA5 '...'
mov al,0x3b ; 0000A9F9 B03B '.;'
out 0x84,al ; 0000A9FB E684 '..'
call xc259 ; 0000A9FD E85918 '.Y.'
;
; Set bit 2 (reserved?) and bit 4 (memory size?) of ROM BIOS Video Mode Options byte @40:0087.
; It would appear that Compaq had a different conception of this byte; however, in the case of an
; adapter like the IBM VGA, it doesn't matter, since the IBM VGA ROM will rewrite this byte anyway.
;
or byte [0x87],0x14 ; 0000AA00 800E870014 '.....'
mov al,0x8e ; 0000AA05 B08E '..'
call xb544 ; 0000AA07 E83A0B '.:.'

74
devices/pc/video/ibm/vga/ibm-vga.nasm
View file

@ -24,8 +24,31 @@
mov [0x10e],cs ; 00000083 8C0E0E01 '....'
sti ; 00000087 FB '.'
mov byte [0x489],0x11 ; 00000088 C606890411 '.....'
mov byte [0x487],0x60 ; 0000008D C606870460 '....`'
call x100 ; 00000092 E86B00 '.k.'
;
; Initialize the ROM BIOS Video Mode Options byte @40:0087 (default to color and 256Kb of RAM)
;
mov byte [0x487],0x60 ; 0000008D
;
; The x100 subroutine alternately enables port 0x3B? and 0x3D? decoding, verifying that there is
; no response on opposing ports 0x3D? and 0x3B?, respectively; otherwise, it assumes that another
; video card must exist and attempts to select co-existing settings for the VGA. For example, if
; there is an unexpected response on the color ports, the VGA ROM will default to mono operation.
;
call x100 ; 00000092
;
; From the "IBM Personal System/2 Model 50 and 60 Technical Reference: I/O Controllers, Video Subsystem", p.4-29:
;
; When in setup mode (I/O address hex 0094, bit 5 equals 0), the VGA responds to a single option select byte
; at I/O address hex 0102 and treats the LSB (bit 0) of that byte as the VGA sleep bit. When the LSB equals 0,
; the VGA does not respond to commands, addresses, or data, on the data bus. When the LSB equals 1, the VGA
; responds. If the VGA was set up and is generating video output when the LSB is set to 0, the output is still
; generated.
;
; The VGA responds only to address hex 0102 when in the setup mode. No other addresses are valid at that time.
; Conversely, the VGA ignores address hex 0102 when in the enabled mode (I/O address hex 0094, bit 5 equals 1),
; and decodes normal I/O and memory addresses.
;
cli ; 00000095 FA '.'
mov dx,0x46e8 ; 00000096 BAE846 '..F'
mov ax,0x16 ; 00000099 B81600 '...'
@ -42,14 +65,35 @@
sti ; 000000B1 FB '.'
push cs ; 000000B2 0E '.'
pop es ; 000000B3 07 '.'
;
; Default to mono settings
;
mov di,0x3b4 ; 000000B4 BFB403 '...'
mov bx,0x1602 ; 000000B7 BB0216 '...'
;
; Test bit 1 of ROM BIOS Video Mode Options byte @40:0087 (set if mono, clear if color)
;
test byte [0x487],0x2 ; 000000BA F606870402 '.....'
jnz xc7 ; 000000BF 7506 'u.'
;
; Choose color settings
;
mov di,0x3d4 ; 000000C1 BFD403 '...'
mov bx,0x1642 ; 000000C4 BB4216 '.B.'
;
; Set the CRTC base port address (0x3B4 for mono, 0x3D4 for color)
;
xc7: mov [0x463],di ; 000000C7 893E6304 '.>c.'
;
; Program the card for a default mode
;
call x1127 ; 000000CB E85910 '.Y.'
xor al,al ; 000000CE 32C0 '2.'
out dx,al ; 000000D0 EE '.'
call x547 ; 000000D1 E87304 '.s.'
@ -2105,7 +2149,19 @@ x1122: mov dx,0x3c8 ; 00001122 BAC803 '...'
out dx,al ; 00001125 EE '.'
x1126: ret ; 00001126 C3 '.'
x1127: mov dx,0x3c4 ; 00001127 BAC403 '...'
;
; Programs the card using data from [BX]; CRTC port address is in DI (0x3B4 or 0x3D4).
;
; Writes 0x01 to SEQ register 0x00 (SEQ.RESET).
; Writes values starting at [BX+0x05] to SEQ registers 0x01-0x04.
; Writes [BX+0x09] to Miscellaneous Output register (MISC).
; Writes 0x03 to SEQ register 0x00 (SEQ.RESET).
; Writes 0x00 to CRTC register 0x11 (CRTC.VERT_RETRACE_END).
; Writes values starting at [BX+0x0A] to CRTC registers 0x00-0x18.
; Writes values starting at [BX+0x33] to ATC registers 0x10, 0x12 and 0x13
; Writes values starting at [BX+0x37] to GRC registers 0x00-0x08.
;
x1127: mov dx,0x3c4 ; (DX) == SEQ port address (0x3C4)
mov ax,0x100 ; 0000112A B80001 '...'
pushf ; 0000112D 9C '.'
cli ; 0000112E FA '.'
@ -2116,14 +2172,14 @@ x1127: mov dx,0x3c4 ; 00001127 BAC403 '...'
mov al,0x1 ; 00001137 B001 '..'
call x1201 ; 00001139 E8C500 '...'
pop bx ; 0000113C 5B '['
mov dl,0xc2 ; 0000113D B2C2 '..'
mov dl,0xc2 ; (DX) == MISC port address (0x3C2)
mov al,[es:bx+0x9] ; 0000113F 268A4709 '&.G.'
out dx,al ; 00001143 EE '.'
mov dl,0xc4 ; 00001144 B2C4 '..'
mov dl,0xc4 ; (DX) == SEQ port address (0x3C4)
mov ax,0x300 ; 00001146 B80003 '...'
out dx,ax ; 00001149 EF '.'
popf ; 0000114A 9D '.'
mov dx,di ; 0000114B 8BD7 '..'
mov dx,di ; (DX) == CRTC port address (0x3B4 or 0x3D4)
mov al,0x11 ; 0000114D B011 '..'
xor ah,ah ; 0000114F 32E4 '2.'
out dx,ax ; 00001151 EF '.'
@ -2134,12 +2190,12 @@ x1127: mov dx,0x3c4 ; 00001127 BAC403 '...'
call x1201 ; 0000115B E8A300 '...'
pop bx ; 0000115E 5B '['
mov dx,di ; 0000115F 8BD7 '..'
add dl,0x6 ; 00001161 80C206 '...'
add dl,0x6 ; (DX) == STATUS1 port address (0x3BA or 0x3DA)
push dx ; 00001164 52 'R'
pushf ; 00001165 9C '.'
cli ; 00001166 FA '.'
in al,dx ; 00001167 EC '.'
mov dl,0xc0 ; 00001168 B2C0 '..'
mov dl,0xc0 ; (DX) == ATC port address (0x3C0)
mov al,0x10 ; 0000116A B010 '..'
out dx,al ; 0000116C EE '.'
mov al,[es:bx+0x33] ; 0000116D 268A4733 '&.G3'
@ -2154,7 +2210,7 @@ x1127: mov dx,0x3c4 ; 00001127 BAC403 '...'
out dx,al ; 00001181 EE '.'
popf ; 00001182 9D '.'
push bx ; 00001183 53 'S'
mov dl,0xce ; 00001184 B2CE '..'
mov dl,0xce ; (DX) == GRC port address (0x3CE)
add bx,byte +0x37 ; 00001186 83C337 '..7'
mov cx,0x9 ; 00001189 B90900 '...'
xor al,al ; 0000118C 32C0 '2.'