> On Feb 1, 2022, at 6:46 PM, Jon Elson via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On 2/1/22 15:40, Paul Koning via cctalk wrote:
>>
>>> On Feb 1, 2022, at 4:31 PM, Grant Taylor via cctalk <cctalk@classiccmp.org>
>>> wrote:
>>>
>>> On 2/1/22 11:23 AM, Paul Koning via cctalk wrote:
>>>> Did any DEC MSCP disks use it?
>>> Please expand "MSCP". My brain is failing to do so at the moment.
>> Mass Storage Control Protocol, the geometry-independent storage access
>> scheme DEC created in the early 1980s. Early implementations include the
>> HSC50 (for VAXclusters) and the UDA50 (Unibus adapter), talking to disk
>> drives such as the RA80.
>>
>> With MSCP, DEC switched to addressing disks by sector offset, as SCSI did
>> later, rather than by geometry (cylinder, track, sector)
>
> All SCSI devices were logical block number, all the way back to the original
> SASI (Shugart Associates System Interface). I had a 10 MB Memorex Winchester
> drive with SASI adapter on my Z-80 CP/M system in about 1981 or so. Maybe I
> misunderstood your sentence above, what the "later" applied to.
I meant that SCSI appeared later than MSCP. And that it used LBA addressing,
but MSCP did it before SCSI.
paul
