The following message is a courtesy copy of an article that has been posted to bit.listserv.ibm-main,alt.folklore.computers as well.
gerh...@valley.net (Gerhard Postpischil) writes: > Perhaps IBM didn't offer a block multiplexer for 360s, but at AMS we > ran a 65 with Memorex 3350s and a C.I.G mux. in the mid-seventies. re: http://www.garlic.com/~lynn/2010h.html#29 45 years of Mainframe 2860 was external selector channel for (at least) 65, 67, 75, 85, 195; as was 2870 was external multiplexor channel. as per previous ... 2880, external block-mux (selector) channel was announced 10feb1970 for 85 & 195 ... possibly because of 3mbyte/sec two-byte feature ... to support 2305-1 that transferred at 3mbyte/sec. however, 2880 could work single-byte ... so 2880 might be able to appear as standard (2860) selector channel except for supporting set-sector ... allowing channel disconnect ... initially 2305 & 3330 ... but also later other devices (if disk driver included set-sector CCW in disk i/o channel program). I haven't seen any ref .. but i somewhat guess that 2880 (at least single-byte mode) would work on any system that 2860 worked with. i would have been much happier if later they had done FBA support rather than calypso and eckd ... aka started out "speed-matching buffer" being able to retrofit 3880 data-streaming 3mbyte/sec channel interface (for 3380 3mbyte/sec disks) ... operating at 1.5mbyte/sec & not data-streaming. getting all the bugs out of calypso/eckd speed-matching and actually working on older (aka 2880, single-byte, 1.5mbyte/sec) channels was possibly more difficult than just simply doing straight-forward FBA support. misc. recent posts being able to do asynchronous, packetized channel programs ... significantly improving channel thruput: http://www.garlic.com/~lynn/2010f.html#16 What was the historical price of a P/390? http://www.garlic.com/~lynn/2010f.html#18 What was the historical price of a P/390? FBA channel programs are able to be packetized .... ckd/eckd weren't (or w/o a lot of difficulty and restriction, special case). misc. past posts mentioning calypso http://www.garlic.com/~lynn/2004o.html#7 Integer types for 128-bit addressing http://www.garlic.com/~lynn/2007e.html#40 FBA rant http://www.garlic.com/~lynn/2007f.html#0 FBA rant http://www.garlic.com/~lynn/2008q.html#40 TOPS-10 http://www.garlic.com/~lynn/2009k.html#44 Z/VM support for FBA devices was Re: z/OS support of HMC's 3270 emulation? http://www.garlic.com/~lynn/2009p.html#11 Secret Service plans IT reboot misc. past posts mentioning ckd, fba, etc http://www.garlic.com/~lynn/submain.html#dasd -- 42yrs virtualization experience (since Jan68), online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
