Elliott 402

The 402 was the last machine from Elliott Brothers (London) Ltd. to have (thermionic) valves as the amplifying devices (excluding the 801 & 802 which still used valves in the trigger drive circuits). The 402E was housed in five cabinets joined in a row and containing standard GPO racking. (For readers who are not familiar with the GPO (often abbreviated to PO) or General Post Office, at that time, all telephone communications equipment and mail handling were under control of the government run GPO). The 402F required two more cabinets to accommodate the floating point hardware. Each cabinet had a door at the front and back and the end cabinets had end-skins. Thus the whole formed a fairly air-tight assembly so that the airflow could be directed through the racks to effect adequate cooling. Each cabinet had an axial extractor fan at the top and each rear door had a filter assembly at the bottom where fresh air was drawn in.