All posts for the month July, 2015

We’re having a hot, muggy summer in LA this year. I’ve been spending more time in the pool than in the workshop. However I have had a bit of time to start preparing my ASR10’s for sale. In doing so, I made an unfortunate, albeit interesting discovery.

I had made a clone of the SCSI board (model SP-3) for the ASR-10. The first batch I did used the same SCSI controller as the original board, an AM33C93 from AMD. For the second batch, I had found some Western Digital WD33C93. The EPS16 SCSI board had used the Western Digital version, so I figured everything would be cool…unfortunately not.

I had done most of the testing on a first-run ASR-10 with a mainboard dated 1992. All the testing with the second batch of SCSI cards was good. However the past week when I was preparing another ASR10, I found some issues. Although it would boot from a SCSI drive, the ‘change storage device’ and ‘copy OS to drive’ would give ‘file operation error’. Long story short, the ASR10 in question had a mainboard dated 1993 which had been redesigned. The newer mainboard did not like the WD33C93, but was happy with the AM33C93. In fact the AMD version worked properly with all revisions.

I did a bit of research and found that the WD versions had several revisions; the latest being 00-08. The chips I used were a mix of 00-04 and 00-06 which were reported to contain various bugs, although I was not able to get the specifics on what was affected. Apparently the AMD version was equivalent, or derived from, the 00-08 version of the WD controller. Perhaps the first generation ASR mainboard was designed to be compatible with the WD controller, and once they switched over to AMD, this compatibility was removed…

So…for anyone who bought the SCSI board with the WD controller (it’s the only square chip and has WD printed on it), I’ll happily replace the board or just the SCSI controller. Contact me and I’ll get it sorted out.