Transistorised Read Amplifier.

This printed circuit is a 'drum' read amplifier.

In Sydney, the auxiliary memory was a drum memory. The drum memory was brought to Melbourne.

The construction of a disk drive was started in Sydney and finished after CSIRAC had arrived in Melbourne. CSIRAC staff and users still called the disk drive a 'drum' even though it was a disk drive

The capacity of the 'drum' (disk) was doubled in Melbourne in 1962. Jurij Semkiw, maintenance officer, designed the read-write system for the 'drum'; this circuit board was a part. There were twenty of these READ circuits. This was a time when transistors became commercially available. Valves were used by WRITE amplifiers because their solid state substitutes, power transistors, were too expensive. The signal transistors were used in READ circuits because they were cheaper.

This amplifier circuit was for the disk drive .

Museum Victoria does not have the chassis (circuit board) that held the READ and WRITE amplifiers; it was not regarded as historic when CSIRAC was donated to the Museum. Jurij believes that the development of the read-write system was his most significant CSIRAC project. The use of the printed ciircuit board was also innovative for the time. Incidentally the circuit board's copper tracks were thick compared to those produced later in the 20th Century. The twenty READ circuits were the only circuit boards used in CSIRAC. Each printed circuit board replaced a valve amplifier.

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