The 704 Card Reader
1955 · High-Speed Reading · Work 595 of 1,871
A card reader drawing cards through at hundreds a minute, the deck in the hopper visibly shrinking, cards with one corner cut ruled into columns with the digits 0 to 9 printed down each column and rectangular holes punched in a scattered pattern, the hopper and the brush contacts close to the lens, thick cables running from the reader to the computer frames, magnetic tape cabinets standing along the wall behind in soft focus, a computer room lit by fluorescent tubes, the cards buff against grey enamel.
- What it was used for
- The IBM 704 was a large-scale computer for engineering and scientific calculations; the Computer History Museum cites "a $2M price tag and weighing over 30,000 lbs" and 123 customers. Its cards were read by a Type 711. The 1955 manual states that model 1 reads 150 and model 2 reads 250 cards per minute, while punching ran at 100 cards per minute. Only part of the card reached the machine: "Only 72 columns of the standard IBM card, however, can be read into core storage" — the accompanying figure labels columns 73 to 80 as "Unused Columns". The reason was word length: each card row was read as two words of 36 bits, and twice 36 is 72.
- What was new
- What is striking about this card reader is its secondary role. The 1955 manual says, at the opening of the chapter on cards: "IN MOST applications magnetic tape is used as the principal input medium." Cards remained for small volumes, "where the volume of input is sufficiently small to permit an economical operation". The same manual has its own chapter headed "PERIPHERAL EQUIPMENT": the Type 714 read cards onto tape, the Type 717 printed from tape — machines without a computer that took the slow work off the 704. IBM Archives gives the reason: an operator who did not want to tie up the whole system with "the relatively slow printing or punching" wrote a tape and hung it on a printer or punch. The barb: the company whose business was the punched card built the 704 so that cards would stay away from it.
What the sources leave open: No monthly rental and no first-installation date for the 704 could be documented; IBM Archives gives only the announcement (7 May 1954) and withdrawal (7 April 1960). The figure 123 appears at the Computer History Museum as a number of customers and elsewhere as a number of machines built — not the same thing. The manual exists only as a scan.