The RC25 (code named Aztec) got started as I was leaving Storage
Engineering. Mike Riggle, VP of Storage Advanced Development (and later
Storage Engineering), recognized early on that to improve seek and
rotational performance, disk diameters (14" for the RA8X series) had to
shrink; 8" or 9" would be the next target. Mike wanted to do only sealed
(Winchester) disks, but there was significant marketing pressure for a
low-end removable disk to succeed the RK11, RK611, and RL11. Hence
Aztec, later the RC25. LESI was, I believe, an attempt to cost-reduce
the RA8X's radial disk interconnect while maintaining performance.
The RC25 was pretty much a disaster, technically and financially, and
the end of the line for DEC's removable disk program. Low end systems
went with ST504-compatible 5.25" sealed disks (the RDXX family), while
the high-end went with 8" or 9" RA9X series, which used the RA8X radial
interconnect. ST504 was eventually replaced by SCSI (and later its
clusterable proprietary variant, DSSI).
/Bob
On 6/25/2019 7:22 PM, Robert Armstrong wrote:
Bob Supnik [b...@supnik.org] wrote:
Ah, yes, the Interconnect Task Force. 1980, perhaps?
....
Can you say anything about LESI, "Low End Storage Interconnect"? It was
used by the RC25 and the TU81+ and, AFAIK, that's it. It never really went anywhere and
there's basically no documentation on it that I've ever seen. I always wondered about
the story behind that.
Thanks,
Bob
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