Re: SCPU question

From: David Wood <jbevren_at_gmail.com>
Date: Tue, 24 Dec 2019 14:20:23 +0000
Message-ID: <CAAuJwiquG7o2Vie=1cgZ9=GKHbh-OznJPkQQG5vMbuE-Ci0JhA_at_mail.gmail.com>
I've not done programming on the SCPU in native mode, but a similar
system in the Apple IIgs has a few recommendations- when calling
legacy software like 8-bit prodos, ensure you call in emulation mode
from bank 0 with all registers set to 8-bit.  This ensures the
environment calling the kernal isn't extremely unusual and should
allow any old software to work without concerns for CPU enhancements
causing unexpected issues.

-jbevren


On Tue, Dec 24, 2019 at 2:06 PM Ullrich von Bassewitz <uz_at_musoftware.de> wrote:
>
>
> It seems I'm doing something wrong with the SCPU.
>
> I have a program that runs in native mode of the SCPU. That is, it does the
> following on startup:
>
>         sta     SCPU_Fast               ; Enable fast mode
>         sta     SCPU_EnableRegs         ; Enable SCPU registers
>         sta     SCPU_VIC_Bank1          ; Enable video optimizations for $4000
>         sta     SCPU_DisableRegs        ; Disable SCPU registers
>         clc
>         xce                             ; Enable 65816 native mode
>         rts
>
> The program itself runs fine until I'm going to call the C64 kernal to load a
> file. Before calling the kernal, I'm doing
>
>         sec
>         xce
>
> but the program crashes when the kernal is called. Switching to slow mode
> manually has no effect (still crashes), so I haven't tried it
> programmatically. Is there anybody else I'm missing?
>
> BTW: The program runs fine in VICE, so I'm not able to debug it in VICE.
>
> Merry christmas everybody!
>
>
>         Uz
>
>
> --
> Ullrich von Bassewitz                                  uz_at_musoftware.de
> Encrypted email preferred                          PGP Key-Id: 29D93B10
>
Received on 2020-05-29 23:58:54

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