IBM 604

Recently I have been taking a course at Virtual High School about computers and one of the assignments was to write about an old computer from the 1940’s or 1950’s.

I decided to write about the IBM 604 Electronic Calculating Punch and here is what I wrote:


The IBM 604 ECP (International Business Machines 604 Electronic Calculating Punch) was introduced by IBM in 1948. Some parts of it were based off of the IBM 603 Electronic Multiplier which was announced in 1946 but few were made.

The IBM 604 ECP could be fed data through punch cards, perform computation such as addition, subtraction, multiplication, and division to the data, and output the results by punching them onto the same card using a type 521 card reader and punch. However, in order to change the programme and computations to be perfomed, the machine’s plugboard had to be opened and the wires had to be moved.

5000 of them where made each of which had 1250 vacuum tubes, ran at 50 kHz, and could run up to 40 programme steps (This was later upgraded to 60). They were about 2m x 2m x 1m and weighted about 640 kilos. According to a newspaper (The ‘Volkskrant’) an IBM 604 ECP was used at the Dutch Tax Authority at some time in 1956.
Later, in 1954 an all transistor version of the IBM 604 ECP was built. It used 2000 transistors but only took 5% of the power and was half the size.

Below is a diagramme of the control panel:

You can still find an IBM 604 Electronic Calculating Punch at the University of Amsterdam Computer Museum and at the American Computer Museum in Montana.