DMA into AltRAM problems again

[dh219]

Reported by ChrisS here: https://www.exxosforum.co.uk/forum/viewtopic.php?p=107764#p107764

Found some issues

1
Because I would like to try the S2 midi module I installed scummvm ST with the Fate of Atlantis.
It seems that when using altram scummst crashes (in various ways when there is HD activity).
I’m not sure if this is a scummvm ST or a hardware issue. (however scummst should support and run from altram)
Also tried it under Emutos. Same result.
As harddisk I used an Ultrasatan. (So it could also be a DMA thingie.)
Without altram ScummST works. (and yes the S2 works).
Don’t have IDE so can’t try that.

• Seems to be an Acsi - Altram issue after some more testing today causing file corruption and read issues.

2
Under TOS 2.06 altram and blitter works however sometimes when the blitter is enabled I see some screen defects.
Mostly missing pixels.

[dh219]

I concur that DMA is unreliable and blitter should most definitely not be used. Earlier firmwares didn't allow it and I think it was a mistake to try to support it with the controller design I implemented. However in addition to that I've been unable to resolve execution from AltRAM issues and so I'm reluctantly going to have to consider DSTB1 end of life and will consider a DSTB2 in due course.

Thanks for the report.