Re: SCSI I/O errors galore, PART II
> Why not faster on the 25-pin connector? Well, every SCSI signal should
> have a seperate ground return pin (which means twisted-pair transmission
> lines end-to-end). That's not possible on the 25-pin designs, so signal
> quality is rather poor. Hence the speed limit...
>
> Now we only need to find out whether their choice of low-speed SCSI
> drives influenced the hardware designs, or the other way round ;-)
You couldn't possibly get anything faster than 5 MB/s on the 68k designs
(no DMA, with the single exception of the IIfx, and even there it's
unclear if MacOS ever made use of it). So 25 pins were OK, slow disks were
OK, and the rest was a backwards compatibilty nightmare.
Michael
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