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The C Users' Group Library 1994 August
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wc-cdrom-cusersgrouplibrary-1994-08.iso
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v_01_05
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1n04035a
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1990-08-19
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2KB
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53 lines
; Listing 4 written for the Phar Lap 386|ASM assembler
code segment dword public use32
assume cs:code ; set HGSC to VGA mode
align 4 ; Copyright 1990 by Gary R. Olhoeft
hstdata equ 0C7000h ; C000:7000
hstctrl equ 0C7D00h
hstadrl equ 0C7E00h
hstadrh equ 0C7F00h
public _setvga_
public _setvga ; function name, no parameters
_setvga_ proc near
_setvga: push ebp ; save old base page (frame pointer)
mov ebp,esp ; make new frame pointer
push es ; save es
mov ax,034h ; access first Mbyte real memory through LDT
mov es,ax ; es points to first Mbyte real memory
mov ax,0D800h ; set 34010 autoincrement
mov es:hstctrl,ax ; write it to 34010 control register
mov ax,0C0h
mov es:hstadrl,ax
mov ax,600h ; 0600:00C0 = set osc. (config.1 reg)
mov es:hstadrh,ax
mov ax,0Ah ; 1010 = current VGA pixel clock; cmd & overlay
mov es:hstdata,ax
mov ax,0E0h
mov es:hstadrl,ax
mov ax,600h ; 0600:00E0 = write configuration (config.2 reg)
mov es:hstadrh,ax
mov ax,0Ch ; 1100 = -h/-v sync, VGA control
mov es:hstdata,ax
mov dx,3C6h
mov ax,4Bh
out dx,al ; port 3C6h, VGA pel mask
mov ax,0C0h
mov es:hstadrl,ax
mov ax,600h ; 0600:00C0 = set osc.
mov es:hstadrh,ax
mov ax,2 ; 0010 = current VGA clock, normal color palette
mov es:hstdata,ax
mov ax,0
mov es:hstadrl,ax
mov es:hstadrh,ax ; set memory address to start
mov ax,3
int 10h ; video display ah = function 00h, al = mode
pop es ; restore es
pop ebp ; restore base page
ret ; return to caller
_setvga_ endp
code ends
end