--------------------------------<snip>---------------------------------
I suspect that 2305 was an outgrowth of the 2302, not necessarily a
"new" device.
I don't have any information on that, although the platters certainly
looked similar to those on the 1301, 1302 and 2302.
Where did the 2301 fit in? IIRC that was a true drum. We had one in
the early 1970s on MVT on both a /65 and a /165, but support was
dropped in MVS.
-------------------------------------<unsnip>--------------------------------
Yes, the 2301 was a true "drum". We used them at NCSS for paging devices
and they seemed to work pretty well. ISTR a silvery-colored drum,
rotating around a verticle axis. We also had a similar device, except
that the finish of the "drum" appeared to be magnetic oxide brown. There
might have been a mixture of 2301 and 2303; it's hard to remember after
almost 40 years.
---------------------------------------------<snip>--------------------------------------------
The 2305 was available with selector channel interfaces
before the blk-mux interfaces. At NCSS we were told that it took a
complete selector subchannel, with eight "exposures", to function
properly so we configured them (16 devices) to run off 2860 Selector
channels hanging off a 370/168 system.
The 2880 was first announced for the S/360; the S/370 was not announced
until 1970, a year after the 360/85, and the original announcement did not
include the 370/168. I'd guess that your management simply did not want to
spend the money on a 2880.
The 2880 wasn't announced for all S/360 models, though. In S/370
architecture there is a block multiplexing control bit in Control
Register 0. S/360 had no architected control registers (yeah, I know -
the /67 did), but perhaps they added them on the /85 and /195?
------------------------------------------<unsnip>--------------------------------------
In my admittedly limited experience, I don't recall ever seing a 2880
channel attached to any S/360. Let me emphasize that my experience is
limited and may not match that of many of my peers here.
Rick
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