SMD disk interface pinout/specs

From: jim <jwstephens_at_cox.net>
Date: Tue Mar 4 04:39:00 2003

Jeffrey Sharp wrote:

> What are the differences between SMD-E and SMD-O? Are there other types of
> SMD? Where can I find more information on SMD?
>

i think you may be referring to the normal density and high density versions.

If I recall original SMD had about 26K / track. EMD drives from CDC had twice

that. density.

The main thing that was a problem was that there was originally a chip that
would
do CRC generation in the original 7400 series IC line. This chip in the same
circuitry
could not keep up with the higher speed SMD and demanded a newer chip.

I recall that most designers went with ECC chips in newer designs, rather than
the
original CRC, as a result of newer logic on the market then.

Our original design at a company I worked for was out in around 1981 or 1982.

If I recall the newer SMD designs were out around 1984 or so. We did not
support them due to having a very small market to support, and low demand for
further updates.

Jim

>
> --
> Jeffrey Sharp
Received on Tue Mar 04 2003 - 04:39:00 GMT