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1955 computer survey in US

Ernst Erb Jürgen Stichling Bernhard Nagel 
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Forum » Radio- and technical History » Technical history: 1920 and later » 1955 computer survey in US
Emilio Ciardiello
Emilio Ciardiello
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01.Sep.09 17:52

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In June 1955 the magazine Electronics revealed that nearly 2800 digital computers had been installed and about 1700 new computers were on order for business operations. The article also gives a survey of computer models available and of the memory types in use at that time. Storage units range from mercury or quartz delay lines to electrostatic cathode ray tubes, from magnetic tapes or drums to a combined tape wrapped around a rotating drum, up to ferrite cores memory arrays. I/O devices include paper tape puncher/readers, card readers, typewriters, up to the faster line printers and to magnetic tapes, capable of handling up to about 30,000 characters per minute, equivalent to 500 bytes per second. Reading the article, one can easily go with the mind to the planetary computers of the science fiction novel ‘Slater’s Planet’ by Harris Moore.

Due to the file format and size restrictions, it is impossible to load the entire pages and the comparative tables. Here is a small selection of few significative models from some manufacturers.

- Bendix built two small models, the D-12 and the G-15A. The first one was composed by two cabinets, containing 720 tubes and 2400 crystal diodes. Magnetic drum storage. A paper tape reader and a 600 char/min typewriter were used as peripheral devices. It was specialized for the solution of equations by numerical integration and required just one mathematician and one operator.

- Burroughs had already installed two UDECs. This model used 3000 tubes and 15 relays in some 31 cabinets, for a power requirement of 32KVA. 8.5” magnetic drum with 5300 words capacity. 125KHz clock frequency. Personnel required to operate it included 5 mathematicians, 1 operator, 2 maintenance men, 1 clerk, and 1 department manager.

- ElectroData had 7 Datatron mainframes installed. Each computer was composed of 16 cabinets, with 1200 vacuum tubes and 3000 crystal diodes. Its 12” magnetic drum had a capacity of 4000 words; it also was equipped with a magnetic tape with a capacity of 200,000 words per reel. 142KHz clock frequency. 2 to 10 mathematicians, 1 operator and 1 maintenance man were required for operation.

- IBM offered several large mainframes, including the 702 and the latest 705, with more than 50 on order at the time. 705 was composed by 22 cabinets and required over than 250 sq. Ft. of floor space and 87KVA power. 5600 vacuum tubes and 11549 crystal diodes were used at 1MHz clock frequency. 20K characters ferrite core memory, plus a 60,000 characters magnetic drum and a 2400ft magnetic tape were used as storage devices. The 20K ferrite core memory replaced the 10000 characters CRT electrostatic storage used in the 702.

- Another big was Remington Rand, with its line of Univac mainframes, culminating in the monsters Univac and Univac Scientific. For a price that started from 1,000,000 USD, one could buy as many as 5600 vacuum tubes, 18,000 crystal diodes and 300 relays. 120KVA were required to operate the standard type, while the scientific just required 45KVA. 1250 sq.ft. minimum of floor space were required to install the standard version. At the date of June 1955, 15 Univac and 8 Univac Scientific were already installed and 14 more were on order. Storage devices included mercury tank delay lines, 1000 words capacity each, and magnetic tapes; the scientific model was equipped with 16Kwords magnetic drum instead of the delay line storage.

- Teleregister had two installations of its custom designed mainframes and 10 more on order. Large 20” drum storage with 70,000 character capacity. Personnel required to operate each computer could include up to 200 clerks and 7 maintenance men.

Magnetic tape storage, IBM
Magnetic drum storage, Teleregister
Mixed tape and rotating drum unit, Clevite-Brush
Mercury tank memory, Univac
Electrostatic CRT storage array, IBM. The oscilloscope on the left was used to        check the content of each storage tube inside the rack units.
Ferrite core memory, IBM
Ferrite closeup view

Operating console of IBM 702
Univac installation

Emilio Ciardiello
Emilio Ciardiello
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Schem.: 165
Pict.: 790
29.Sep.09 19:31

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In 1955 IBM announced sales and orders in its high-end data processing machines for some 1,000 units. EDPM (Electronic Data Processing Machines) included only computers with sophisticated internal programming for business or scientific data handling, with the exclusion of simple electronic calculators or desk machines. The forecast approached the figure of 1,000 computers, including 181 one-million-dollar-plus 700 series, 31 installed and 150 on order, plus 780 smaller series 650, 80 already installed and 700 on order.

Some very interesting new features, other than ferrite-core memories, and development steps to be introduced in the new products through the year were also announced. A ‘juke-box type’ (disk) random access memory was used in the compact model 305 from the fall.

A 2.5-megabit juke-box storage unit, which can be considered as forerunner of hard disks still in use today. The information was stored on both surfaces of each disk. Heads were positioned by pneumatic actuators and escaping air was used as protective cushion for the magnetic surfaces. Several units could be connected in parallel to extend storage capacity.

The large scientific model 704 and the equivalent business model 705, both released from the fall, came with ferrite-core memories for fast internal storage. For the same 700 series a 1000 lpm (line-per-minute) printer had been announced.

The trend of new computer machines was for a single architecture, capable of handling either scientific or business works with comparable efficiency. The 702, 704 and 705 were already capable to communicate with each other and handle someway both scientific and business tasks.

One of the most important announcement was the release of the first Fortran compiler for January 1956. Fortran was the acronym of ‘Formula translation’ and has been used for a long while as scientific programming language.

IBM also introduced a new concept of fault-tolerance, connecting two 704 computers in tandem. One machine could act as a spare in case of failure in the second one.

Also other manufacturers were innovating their computer lines. National Cash Register (NCR) was delivering two special purpose CRC-105’s to Convair, San Diego, to solve differential equations in aircraft and missile applications. These computers had to process the results coming from analog computers like this one.

Burroughs had installed a check-processing unit at the First National City Bank of New York. The machine, using optical character recognition, was capable of reading serial numbers on 7200 checks an hour. Used to process peaks of some 130,000 travelers’ checks per day, the photoelectric reader shown below did the work of 50 clerks.


The same Burroughs introduced its 900-lpm fast printer. Also an electrographic printer similar to a laser printer, capable of 5000 characters per second, was under development.

Sperry Rand introduced a small business computer using magnetic-amplifier units, known as micro-feractors, to replace electron tubes or transistors. Librascope introduced the equivalent of a scientific personal computer. The desk-sized machine had 16 basic instructions, 30 bit words and an internal magnetic-drum memory capable of storing 4096 words. It was sold for less than 30.000 dollars. Here is its internal view.


This article was edited 30.Sep.09 08:04 by Emilio Ciardiello .