Talk:IBM 729

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Storage size[edit]

This article needs clearer information on approximate storage capacities of the system... a single 2400 foot tape could store the equivalent of some 50,000 punch cards doesn't make much sense. -Rolypolyman (talk) 01:52, 26 November 2007 (UTC)

A punched card had 80 columns, each holding one character of data. That's why terminal windows are still usually 80 columns wide :-) So "50,000 punch[ed] cards" is about 3.8MiB. RossPatterson (talk) 02:36, 26 November 2007 (UTC)
The exact amount depended on record blocking, i.e how many card images per record. If you only had one card image per record, one tape could only hold about 20800 cards. Most of the tape would then consist of those 3/4" record gaps. And, of course, each character was only 6 bits. 4 megabytes may not sound impressive now, but a couple of tapes held the equivalent of a large file cabinet's worth of punch cards.--agr (talk) 19:00, 26 November 2007 (UTC)