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Old 14 July 2016, 09:31   #8
Join Date: Jun 2010
Location: out in the wild
Posts: 1,134
Originally Posted by TjLaZer View Post
Will this suffer the same 16bit vs 32 bit problems with SCSI controllers? I could never get my SCSI cards working right with the DKB 2632 card as it needed the 16-bit buffer to run ok.

Would of been cool of this had a IDE port on it
Unfortunately, Fast IO (or "any IO") on the memory port is impossible, because the Caches can't be disabled - there is a signal missing on the port to do exactly that.

What you're calling 16-bit memory is probably memory in the lower 16MBytes of address space, which I normally call "24-bit memory" - just because of the number of address bits. Both is correct, as the Z2 data bus width is 16 bits, so this is just my "common use", not necessarily universally correct.

And yes, if your SCSI controller requires 24-bit memory to DMA into, it will have the same problems with BigRAM2630 as with a DKB memory expansion. There are ROM patches for A2091 and GCP controllers to be PIO mode only - not sure if a GuruROM will solve it, but it's worth looking into.

If Z2 mem is not available, the SCSI controller's software *should* automatically revert to using Chipram. This results in slow performance, but it should work. What SCSI controller are we talking about here?

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