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Small bug in XCDROM32 that may also be found in UIDE/UDVD2 (Developers)

posted by mceric, Germany, 22.05.2026, 09:30

> Hello,
>
> recently a small bug was fixed in xcdrom32 that affected game "Tempest
> 2000":
>
> https://github.com/Baron-von-Riedesel/Jemm/issues/44
>
> The fix is rather trivial:
>
>
> ReqMCS:
> call DoIOCmd        ;Issue "Test Unit Ready" command.
> mov edi,[AudAP]     ;Get media-change flag from table.
> mov al,[edi-1]
> mov [esi+1],al      ;Return media-change flag to user.
> ;--- v1.6: set audio status busy flag
> ;    ret
> jmp ReadAudioSt
>
>
> Since xcdrom32 is based on one of J.R. Ellis' drivers (~ 20 years ago),
> those drivers may also benefit from a fix.

The latest FreeDOS package gathered by Mercury13 in 2021 indeed needs the fix:


;
; CD/DVD IOCTL Input "Media-Change Status" handler.
;
ReqMCS: call    DoCmd           ;Issue "Test Unit Ready" command.
        mov     di,[bx+AudAP-@] ;Get media-change flag from table.
        mov     al,cs:[di-1]
        mov     es:[si+1],al    ;Return media-change flag to user.
        ret                     ;Exit.


---
FreeDOS / DOSEMU2 / ...

Complete thread:

• Small bug in XCDROM32 that may also be found in UIDE/UDVD2 - Japheth, 22.05.2026, 08:02 (Developers)
  • Small bug in XCDROM32 that may also be found in UIDE/UDVD2 - mceric, 22.05.2026, 09:30