[email protected] (Tom Brennan) writes: > Me too - until just a few days ago when I happened upon a number of > 3380's defined at a client site. All I can guess is these were still > real 3380's at the time they needed to be moved to a DS8000. TASID > shows them as 3380-TC3 (whatever that is) at 3,339 cyls. I think I > remember a type 3380-K (triple density?), but much of those years is > just a blur to me.
original 3380 (1981) had twenty track width spacing between (885) tracks ... they then doubled (1770, 3380E, 1985) and then tripled (2655, 3380K, 1987) the number of tracks ... by cutting the inter-track spacing. http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3380.html 3390 announce nov1989 http://www-03.ibm.com/ibm/history/exhibits/storage/storage_3390.html however, as periodically mentioned, there haven't been real CKD DASD manufactured for decades, all just emulation on industry standard fixed-block disks. http://www.garlic.com/~lynn/submain.html#dasd as an aside ... even 3380s CKD were really (32byte) fixed-block http://www.bitsavers.org/pdf/ibm/dasd/reference_summary/GX26-1678-0_3380_Reference_Summary_Feb83.pdf all disk technology was moving to fixed-block by the late 70s ... but MVS inability to come up with fixed-block support required CKD emulation long after CKD was obsolete. there was special 3380j end of 1988 ... which had avg. seek of 12ms and max. seek ms 21 ... compared to 16ms & 29ms for 3380k ... but the 3380j had only 885 tracks (same capacity as original 3380) ... one is tempted to believe that the 3380j might have really been a 3380k limited to only accessing 1/3rd of the platter (note seek time isn't strictly linear since there is acceleration latency). recent post mentioning early 80s semi-facetious discussion at SHARE about doing a "fast" 3380 (with fewer tracks by microcode change). http://www.garlic.com/~lynn/2014m.html#87 Death of spnning disk? >From IBM 3380 history reference: In September 1987, IBM announced a significant extension to the 3380 series: the Model K DASD that stored 7.5 billion characters of information, and the densest disk device IBM ever manufactured; and the high-speed Model J, which could locate data faster than any previous 3380 DASD. The Model J found the correct information track in an average time of just 12 thousandths of a second. Customers who installed Model Js, which could store 2.5 billion characters of data, could upgrade it to the denser Model K. ... snip ... -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
