DOS ain't dead

Video BIOS shadowing on modern systems. (Users)

posted by CandyMan, 26.12.2023, 19:48

> Thanks for the tip. I'm looking at JEMM and the possibility of modifying it
> to map the vBIOS ROM code using a similar "trick" as is done with the /C
> parameter in moving the 4k BIOS font to (modifiable) XMS memory instead.

;JEMM must be loaded similarly like this (C=specify BIOS fonts region to shadowing):
;DEVICE=JEMM386.EXE C=C800-CDFF
        org     0100h
        xor     eax,eax
        mov     fs,ax
        cmp     [fs:4*67h],eax
        jz      .Exit
        mov     ax,1130h
        mov     bh,6
        int     10h
        mov     eax,es
        shl     eax,4
        movzx   edi,bp
        add     edi,eax
        mov     eax,cs
        shl     eax,4
        lea     esi,[eax+Fonts]
        mov     ecx,256*16
        mov     ax,0xDEFF
        int     67h
        or      ah,ah
        jnz     .Exit
        mov     ax,3
        int     10h
.Exit:  ret

Fonts:  file    "special.f16"

https://megawrzuta.pl/download/a77122f5e01d9d929aa79e761b365f7a.html

Complete thread:

• Video BIOS shadowing on modern systems. - Zyzzle, 02.02.2023, 10:54
  • Video BIOS shadowing on modern systems. - tom, 02.02.2023, 14:24
    • Video BIOS shadowing on modern systems. - bretjohn, 02.02.2023, 18:02
      • Video BIOS shadowing on modern systems. - Zyzzle, 03.02.2023, 02:53
        • Video BIOS shadowing on modern systems. - CandyMan, 06.02.2023, 00:26
          • Video BIOS shadowing on modern systems. - bretjohn, 07.02.2023, 15:47
            • Video BIOS shadowing on modern systems. - Zyzzle, 10.02.2023, 05:25
              • Video BIOS shadowing on modern systems. - CandyMan, 10.02.2023, 09:52
                • Video BIOS shadowing on modern systems. - Oso2k, 11.02.2023, 23:54
                  • Video BIOS shadowing on modern systems. - CandyMan, 12.02.2023, 09:24
                    • Video BIOS shadowing on modern systems. - tom, 12.02.2023, 12:00
                • Video BIOS shadowing on modern systems. - Zyzzle, 22.02.2023, 10:24
                  • Video BIOS shadowing on modern systems. - CandyMan, 26.12.2023, 19:48