sme...@gmu.edu (Seymour J Metz) writes: > The 3330 was not the first disk drive with Set Sector; that honor > belongs to the 2305, formally part of the S/360 series rather than the > S/370, although I imagine that a lot more were sold for use on, e.g., > 370/165, than for 85 or 195.
re: http://www.garlic.com/~lynn/2018.html#77 CKD details http://www.garlic.com/~lynn/2018.html#79 CKD details 2305 was also fixed-head disk (head per track, sort of replacement for 2301 & 2303 fixed-head drums) ... so there was no arm movement latency, just rotational delay. most internal sites used 2305-2 as paging device, approx. 11mbyte capacity, 1.5mbyte transfer. There was 2305-1, same number of heads, but only half the tracks, two heads positioned on track, offset 180degrees and transferred in parallel for 3mbytes/sec (special two byte channel), half the number of tracks, (little less than) half the capacity and half the rotational delay ... basically even/odd bytes that could start as soon as came under either offset/opposing heads. https://www-03.ibm.com/ibm/history/exhibits/storage/storage_2305.html and https://www-03.ibm.com/ibm/history/exhibits/storage/storage_PH2305.html 2305 also had "multiple exposure" support ... eight device addresses ... uniform formating of tracks ... software strategies for the eight addresses could be used to let the controller maximize the transfer per rotation. very late 70s, early 80s, IBM contracted with vendor for electronic disks (for paging use at internal datacenters) ... referenced as model 1655, could simulate 2305 or operate natively (more like FBA) ... no arm motion, no retational delay. some old email http://www.garlic.com/~lynn/2007e.html#email820805 as aside, 3380 3mbyte channel used "data streaming" ... channels had used protocol that did end-to-end handshaking on every byte transferred, "data streaming" support would transfer multiple bytes per end-to-end handshake ... allowed for increasing data transfer rate as well as doubled maximum channel cabling distance. trivia: ECKD was originally used for calypso ... speed-matching 3880 controller feature that allowed 3380 3mbyte/sec to used with 168 & 3033 1.5mbyte/sec channels (took enormous amount of work to get all the kinks worked out, i've frequently commented it would have been less effort to have just moved to FBA). some old email http://www.garlic.com/~lynn/2007e.html#email820907b a little more in these posts http://www.garlic.com/~lynn/2010e.html#36 What was old is new again (water chilled) http://www.garlic.com/~lynn/2015f.html#83 Formal definituion of Speed Matching Buffer recent post trying to get 2nd "exposure" (device address) for the 3350 fixed-head feature (allowing data transfer overlapped with arm motion) http://www.garlic.com/~lynn/2017k.html#44 Can anyone remember "drum" storage? getting to play disk engineer in bldgs 14&15 posts http://www.garlic.com/~lynn/subtopic.html#disk CKD, FBA, multi-track search, etc posts http://www.garlic.com/~lynn/submain.html#dasd other past posts discussing 2305 & 1655 http://www.garlic.com/~lynn/2001c.html#17 database (or b-tree) page sizes http://www.garlic.com/~lynn/2001l.html#53 mainframe question http://www.garlic.com/~lynn/2002.html#31 index searching http://www.garlic.com/~lynn/2002l.html#40 Do any architectures use instruction count instead of timer http://www.garlic.com/~lynn/2003b.html#15 Disk drives as commodities. Was Re: Yamhill http://www.garlic.com/~lynn/2003b.html#17 Disk drives as commodities. Was Re: Yamhill http://www.garlic.com/~lynn/2003c.html#55 HASP assembly: What the heck is an MVT ABEND 422? http://www.garlic.com/~lynn/2003m.html#39 S/360 undocumented instructions? http://www.garlic.com/~lynn/2004d.html#73 DASD Architecture of the future http://www.garlic.com/~lynn/2004e.html#3 Expanded Storage http://www.garlic.com/~lynn/2005e.html#5 He Who Thought He Knew Something About DASD http://www.garlic.com/~lynn/2005r.html#51 winscape? http://www.garlic.com/~lynn/2006.html#38 Is VIO mandatory? http://www.garlic.com/~lynn/2006c.html#1 Multiple address spaces http://www.garlic.com/~lynn/2006e.html#46 using 3390 mod-9s http://www.garlic.com/~lynn/2006k.html#57 virtual memory http://www.garlic.com/~lynn/2006r.html#36 REAL memory column in SDSF http://www.garlic.com/~lynn/2006s.html#30 Why magnetic drums was/are worse than disks ? http://www.garlic.com/~lynn/2007e.html#59 FBA rant http://www.garlic.com/~lynn/2007o.html#26 Tom's Hdw review of SSDs http://www.garlic.com/~lynn/2007s.html#9 Poster of computer hardware events? http://www.garlic.com/~lynn/2007u.html#4 Remembering the CDC 6600 http://www.garlic.com/~lynn/2008b.html#15 Flash memory arrays http://www.garlic.com/~lynn/2010g.html#11 Mainframe Executive article on the death of tape http://www.garlic.com/~lynn/2010g.html#22 Mainframe Executive article on the death of tape http://www.garlic.com/~lynn/2010g.html#55 Mainframe Executive article on the death of tape http://www.garlic.com/~lynn/2010h.html#78 Software that breaks computer hardware( was:IBM 029 service manual ) http://www.garlic.com/~lynn/2011e.html#75 I'd forgotten what a 2305 looked like http://www.garlic.com/~lynn/2011j.html#9 program coding pads http://www.garlic.com/~lynn/2012n.html#43 history of Programming language and CPU in relation to each http://www.garlic.com/~lynn/2013d.html#0 Query for Destination z article -- mainframes back to the future http://www.garlic.com/~lynn/2014b.html#64 Mac at 30: A love/hate relationship from the support front http://www.garlic.com/~lynn/2015b.html#35 Deny the British empire's crimes? No, we ignore them http://www.garlic.com/~lynn/2016d.html#24 What was a 3314? http://www.garlic.com/~lynn/2016f.html#23 Frieden calculator http://www.garlic.com/~lynn/2017b.html#68 The ICL 2900 http://www.garlic.com/~lynn/2017b.html#69 The ICL 2900 http://www.garlic.com/~lynn/2017c.html#26 Multitasking, together with OS operations http://www.garlic.com/~lynn/2017d.html#63 Paging subsystems in the era of bigass memory http://www.garlic.com/~lynn/2017d.html#65 Paging subsystems in the era of bigass memory http://www.garlic.com/~lynn/2017e.html#36 National Telephone Day -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
