| Re: [hatari-devel] Blitter bug in STe mode |
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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [hatari-devel] Blitter bug in STe mode
- From: Christian Zietz <czietz@xxxxxxx>
- Date: Tue, 9 Jun 2020 07:33:57 +0200
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Roger Burrows schrieb:
> On 8 Jun 2020 at 23:58, Vincent Rivière wrote:
>
>> On 08/06/2020 à 23:31, Christian Zietz wrote:
>> > Hatari sometimes restarts the Blitter in the middle of a TAS
>> > instruction;
>>
>> Wow. I wasn't aware that EmuTOS used the TAS instruction. That one is
>> completely forbidden on Amiga. Fortunately, the Blitter code is not run on
>> that machine.
>>
> Atari TOS also uses the TAS instruction, so that's why I deemed it safe ....
It is. The TAS instruction is there to *prevent* what currently is
happening on Hatari. With BSET #7,... the Blitter can take the bus
in-between the read and the write cycle. With TAS it shouldn't be able
to. Therefore, imho it's the right choice to use TAS (as recommended by
Atari) to restart the Blitter.
Regards
Christian
--
Christian Zietz - CHZ-Soft - czietz@xxxxxxx
WWW: https://www.chzsoft.de/
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