Zorro DMA vs Accel. DMA: Cyberscsi vs A4091

[doctorq]

I've seen an old post by Pasha saying there is a version of the scsi module that tolerates overclocking but I've yet to see a report with an 80Mhz MkII with working scsi.

IIRC Pasha stated that SCSI modules containing the glogic chip could be overclocked, whereas the SCSI modules with the Symbios chip couldn't. I have a Cyber SCSI MKII with glogic chip, and when I tried to overclock, I couldn't get it to start up with even a 60 MHz oscillator. I doubt that you will find someone with a MKII running at 80 MHz with the SCSI module running as well.

[doctorq]

@doctorq
Have you tried just various oscillators ? It could be a timing issue. Also, do you have 70ns ram ? If so ram could be the limiting factor.

It was just a very quick test, without any kind of tweaking at all. All I did was to replace the 50 MHz oscillator with a 66 MHz, 60 MHz and a 56 MHz. It was just with the 56 MHz oscillator I saw some sign of life. Ram was rated at 60 ns.

As said, it was just a quick test, and some tweaking may have gotten the card to boot at higher speeds. Even at 60 ns, I still suspect the ram could have something to do with it due to the build quality.

I never have gotten around to mess with it some more due to lack of time, others might succesfully have overclocked their CSMK2. I still have my doubt about succesfully overclocking to above 66 MHz with fully and stable working SCSI as well.