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Fix CPU test to properly handle 808x vs V20.

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This commit is contained in:
Matthieu Bucchianeri
2025-02-10 18:39:59 -08:00
parent c768ae500d
commit 6fd29c313d
2 changed files with 106 additions and 106 deletions
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14
XTMax/Drivers/BootROM/bootrom.asm
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@@ -94,25 +94,25 @@ entry:
mov word ds:[0xffff], 0xaaaa ; write signature at test location
cmp byte ds:[0], 0xaa ; 8086 will write the 2nd byte at offset 0
mov ds:[0xffff], ax
je .test_v20
jmp .support_string_io ; we have an 80186/80188
jne .support_string_io ; we have an 80186/80188
.test_v20:
push ax ; save results
xor al, al ; force ZF
mov al, 0x40 ; multiplicand
mul al ; V20 doesn't affect ZF
pop ax ; restore results
jz .support_string_io ; we have an V20
xor dl, dl
jmp .store_string_io
jnz .not_support_string_io ; not a V20
.support_string_io:
mov dl, 1
mov ax, string_io_msg
call print_string
jmp .store_string_io
.not_support_string_io:
xor dl, dl
.store_string_io:
mov ax, XTMAX_IO_BASE+3 ; scratch register 0
mov ax, XTMAX_IO_BASE+3 ; scratch register 0
xchg ax, dx
out dx, al ; save capability
out dx, al ; save capability
%ifndef AS_COM_PROGRAM
;