1 Jun
2014
1 Jun
'14
9:37 a.m.
On 06/01/2014 08:48 AM, Paul Koning wrote:
Yes and no. Yes, the group mark would act as the
logical end of data
mark, ending the read instruction. But the physical sector size was
always 200 digits.
True, but it shows that there was a precedent for recording
variable-length records.
By contrast, the 360 disk format would actually write
physical blocks
the size you asked for.
I don't see much advantage to this--it would seem to make effective
packing of sectors on a track.
I?m not familiar with those ? only worked on 844
drives, which DEC
users know as the RP04.
I remember when the 844 was released--they replaced the very troublesome
808-sized 821 drives we were using. I don't think the 821 saw any
widespread distribution outside of Special Systems. They were an utter
disaster.
We used the 844s with a MAC and an expander. One of our customers had
144 of them on site, hooked to 4 Cyper 74s, coupled together with 4MW of
ECS. Lots of QSEs in that one.
The 852 was 1311-compatibe; the 853 was sort of 2311-ish. The packs
would fit either drive and were hard-sectored. You could use them in
"track-at-a-time (unsectored)" mode or in sector mode. They were not fast.
If Spence Preston is still around, he'd know just about everything there
is to know about 844s--he spent a lot of plane time putting out fires on
those.
--Chuck