ICT 1301

Typical of mid-sized machines of the era, they used core memory, drum storage and punched cards, but they were unusual in that they were based on decimal logic instead of binary.

The machine ran at a clock speed of 1 MHz and its arithmetic logic unit (ALU) operated on data in a serial-parallel fashion—the 48-bit words were processed sequentially four bits at a time.

The electronics consist of over 4,000 printed circuit boards each with many germanium diodes (mainly OA5), germanium transistors (mainly Mullard GET872), resistors, capacitors, inductors, and a handful of thermionic valves and a few dozen relays operated when buttons were pressed.

[1] One of their main attractions was that they performed British currency calculations (pounds, shillings and pence) in hardware.

The London University machine was restored to working condition by a group of enthusiasts completing their task in 2012.

It also had 400 words of 'reserved' storage where the computer's bootstrap program (then called Initial Orders) was stored.

Up to eight Ampex TM4 tape decks, running at 75 inches per second for a throughput of 22,500 digits per second, could be connected.

Towards the end of the life of the 1301, a single ICT standard interface could be added to allow data to be written to the by-then industry-standard magnetic tape.

A drum with only a quarter of the read/write heads fitted was commonly used, giving 3,000 words of 48 bits as backing storage.

"Flossie" is the nickname given to an ICT 1301 (as of 2013[update]) in storage at The National Museum of Computing at Bletchley Park, England.

[6] A second ICT 1301, which is close to operating condition, is on display at the Toitū Otago Settlers Museum in Dunedin, New Zealand.

This computer — the first in the city of Dunedin — was originally used by the Cadbury confectionery factory for calculating invoices and payroll.

The machine belongs to the Time-Line Computer Archive museum and although nearly complete, is not in working condition.