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CSIRAC - Input & Output Devices

Don Beresford at console

Image: Don Beresford at console

Source: Museum Victoria

At the time the CSIR MK1/CSIRAC was developed, both punch cards and 5 hole paper tape were in general use to store data for business machines and messages in communication systems.

Initially the CSIR MK1 was equipped with Hollerith punch card input and output equipment. When this proved unsatisfactory, a unique form of 12 hole paper tape equipment was developed - rather like a continuous 12 channel punch card.

Before 1958, all paper tape inputs to CSIRAC were with 12 hole tape; outputs were either on 12 hole tape or teleprinter. The teleprinter was the only alphanumeric output. 5 hole tape was introduced in 1958. Because it was much faster than 12 hole tape, it was used for output; there was not much difference to the speed of input. All the existing library of tapes were 12 hole. 5 hole paper tape technology was introduced around 1959.

The new 5 hole tape was used for data input. Controls on the switchboard were used during a program run to switch manually from 12 hole tape to 5 hole tape - the computer was not fully automatic.

In practice, the 12 hole tape was used primarily for program storage and input and the 5 hole tape equipment was used for data input and output.

Flexowriter equipment was used for the preparation of 5 hole and to print out computer output on 5 hole tape. Some specialist users brought data on 5 hole tape which had been collected by 5 hole data logging equipment in the course of their experiments.

Interprogram (a more user friendly English language program) was written for a 5 hole tape reader. The booting program was always 12 hole but the actual Interprogram instructions were delivered on 5 hole tape. Near the end of CSIRAC's 'life', all the programming was fed in on 5 hole tape. 5 hole tape output was printed out on a flexowriter, which was more reliable than a teleprinter.

The flexowriter was not connected to anything on CSIRAC. It was used to translate 5 hole tape into alphanumeric characters. The flexowriter had three functions: to produce 5 hole tape, read 5 hole tape and as a simple typewriter.

The off-line editing suite had its own 12 hole reader and punch. CSIRAC had its own 12 hole reader and punch. The current display in Melbourne Museum does not include the 12 hole punch and reader that were associated with the off-line editing suite.

Speeds of the CSIRAC peripherals:

Drum 20 msec/cycle of 1024 locations
5 hole punch 20 characters/sec
12 hole punch 15-18 characters/sec
5 hole reader 100 characters/sec
12 hole reader 35-50 characters/sec

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