Acorn System 1

• one card with the I/O part of the computer: a LED seven segment display, a 25-key keypad, and a cassette CUTS interface
• the second card, which included the CPU, RAM/ROM memory, and support chips
• the two boards were interconnected by a semi-flexible, multi-conductor cable, known by its commercial name 'Spectra Strip'
• the whole assembly was held together by four 2.5mm × 20mm nylon screws and clear plastic spacing tubes for rigidity.

• Top Row: INS8154 RAMIO Integrated Circuit, 6502 CPU, 2 × 2114 1024×4 RAM, 2 × 74S571 512×4 PROM, RAM/ROM expansion socket, second INS8154 for peripheral expansion.
• Bottom row: 1 MHz clock crystal, 4 × TTL logic chips providing address decoding for the memory and I/O expansion, 5V regulator.
• The smaller empty socket in the middle of the board was used to set the memory map of the RAM, ROM and I/O expansion by fitting or soldering wires between various positions according to the instructions in the Acorn System 1 Technical Manual.
• The three semi-circular legends on the bottom left of the board marked positions for optional push switches to trigger the board's RESET, IRQ and NMI lines.