300mb disc drives

[Eric Smith]

William wrote:
> Around 1982 or so, an RP-20 showed up at CMU.  As I
> recall, it stored an entire gigabyte on a pair of
> HDAs in a single cabinet.

I'm not sure whether IBM made the HDAs, drives, or perhaps the
entire drive cabinet, but the RP20 subsystem used drives with
an IBM bus/tag interface, attached via a DX20 Massbus-to-IBM-bus/tag
interface, which was a fancy microcoded thing.

There was also a TX20 formatter for IBM bus/tag tape drives; I think
it may have been a DX20 running different microcode.