From mboxrd@z Thu Jan 1 00:00:00 1970 From: paul.winalski@gmail.com (Paul Winalski) Date: Wed, 25 Apr 2018 16:54:16 -0400 Subject: [TUHS] 3330s, 3340s, Winchesters... (was: /dev/drum) In-Reply-To: <20180425005251.GL31055@eureka.lemis.com> References: <3A18DFEC-42B7-4234-9DD1-367733270D50@tfeb.org> <0abe01d3db28$b6573660$2305a320$@ronnatalie.com> <4b95c9f6-0190-be93-7284-d03be289c4ba@gmail.com> <20180424032830.GJ31055@eureka.lemis.com> <20180425005251.GL31055@eureka.lemis.com> Message-ID: On 4/24/18, Greg 'groggy' Lehey wrote: > > Hmm. The earliest 3330s had 100 MB per disk, considerably more than > the 3340. I had thought that the 3340 had fewer surfaces. And the > 3330s definitely only had one disk per unit, though they brought out > an 8-drive cabinet with a whopping 2.4 GB (by the time I used them). The 3340 indeed had fewer platters per unit than the 3330, and because of that a lower disk capacity. Both the 3330 and 3340 were CKD format, not fixed-block, so the capacity depended on the record size. Highest storage capacity was achieved with one record with a zero-length key field covering the full track (called full-track blocking). According to the IBM Archives web page (https://www-03.ibm.com/ibm/history/exhibits/storage/storage_3330.html), the 3330 was code-named Merlin. It could have from 2 to 16 spindles per controller. Originally each disk pack had a maximum capacity of 100 MB. The 3330 model 11 used IBM 3336 disk packs that had double the original capacity (up to 200 MB). This IBM Archives web page (https://www-03.ibm.com/ibm/history/exhibits/storage/storage_3340.html) says that the 3340 was code-named Winchester. This page reports, but does not verify, the "30-30" Winchester rifle story. The IBM 3348 Data Module, the disk pack equivalent for the 3340, was a sealed module that contained the head assembly. This reduced the hazards of head misalignment and surface contamination. Unlike later sealed-module disks, the 3348s were removable media. Modules with maximum capacities of 35 MB or 70 MB were available. There was also a 70 MB module with up to 0.5 MB accessible from fixed heads. -Paul W.