Ken Shirriff @righto.com · 24d

IBM had a series of aerospace computers called System/4 Pi. These computers all used standard-sized boards (top). Except that the I/O Processor's boards (bottom) were one inch wider. I guess they needed the extra space for more circuitry.

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Ken Shirriff · 24d

This diagram shows how the circuit boards (called pages) were plugged into the I/O Processor's aluminum-alloy case. For storage, the system used magnetic core memory, larger pages at the back. This system didn't use a microprocessor; it was built from 11 logic pages crammed with simple chips.