Xah Lee's Unixism

Anne & Lynn Wheeler lynn at garlic.com
Fri Sep 10 23:10:08 CEST 2004

Morten Reistad <firstname at lastname.pr1v.n0> writes:
> These are the IBM gear that most resemble SMB equipment. SMD's were
> the BUNCH answer to DEC's RP04/5/6 and IBM's 3330. Originally made
> by CDC; others also produced them. NCR and Fujitsu come to mind.
> Originally existed as 80-megabyte, pretty light units (30 kg); later
> expanded to 160-megabyte. Then the real washing machines turned up;
> 300 mb (315 unformatted megabytes). Originally 4 on a chain, 15 mbit
> analogue readout (MFM ISTR; they never tried RLL).
> These were a mainstay among the smaller mini vendors from approx
> 1974 to the advent of winchesters around a decade later. The
> earliest winchesters made exact hardware replicas of the SMD. Then
> the spec was expanded and became ESMD, but ESMD was never as
> robustly standardized. Sacrifices of goats, PHBs and undergraduates
> was needed to stabelize long ESMD chains.

some number of the senior disk engineers left in the late '60s and
early '70s .... fueling the shugart, seagate, memorex, cdc, etc disk
efforts. in fact, the excuse given (later half 70s) for dragging me
into bldg. 14 disk engineering conference calls with the pok
cpu&channel engineers was that so many of the senior disk engineers
(that were familiar with the channel interface) had left.

random disk history URLs from around the web:

search engine even turns up one of my posts that somebody appears
to be shadowing at some other site:
of course the original

in the previous posting
this reference
also gave the speeds and feeds for 3350 (including 317mbyte capacity).

the 1970s washing machines were the 3340s & 3350s ... but the 3350s
enclosed and not removable/mountable; 3340s .... which had
removable/mountable packs .... included the head assemble & platters
completely enclosed.

3340 (winchester) reference, picture includes removable assembly on
top of drives ("3348 data module"):

picture of row of 3350 drives is similar to that of 3340s ... except
the 3350 packs weren't removable and had much larger capacity

postings reference product code names:
http://www.garlic.com/~lynn/2001l.html#53 mainframe question
http://www.garlic.com/~lynn/2003b.html#7 Disk drives as commodities. Was Re: Yamhill

3340-35 was code named Winchester and as per the IBM 3340 ULR began shipping
to customers november, 1973.

we had a joke when the 3380s were introduced about filling them
completely full. if you converted an installation with say 32 3350
drives .... to 16 3380s (sufficient to hold 32-3350 drives worth of
data, 10gbytes) ...  you could have worse performance ... while 3380s
were faster than 3350s, there weren't twice as fast. the proposal was
to have a special microcode load for the 3880 controller .... which
would only support half of a 3380 disk drive. There were a number of
customer people (mostly technies) at share which thought it would be a
good idea ... and furthermore that ibm should price these half-sized
3380s higher than full-sized 3380s (to make the customer exectives
feel like they were getting something special). They would be called
"fast" 3380s (because avg. seek only involved half as many cylindes)
and it was important that the limitation be built into the hardware
and be priced higher. It was recognized that installations could
create their own "fast" 3380s ... just by judicious allocation of data
and no special microcode. However, it was pretty readily acknowledged
that w/o the hardware enforced restrictions, that there were all sorts
of people that populate datacenters that would be unable to control
themselves and fully allocated each 3380.

Anne & Lynn Wheeler | http://www.garlic.com/~lynn/

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