“Mighty Oaks Grow From Small Acorns”
The System 1 released in 1979 was Acorn’s first computer kit. Constructed from two (160 x 100 mm) Eurocard boards, the first a 1MHz 6502 CPU card & the second is the System 1 keyboard card linked by a ribbon cable and powered by an external 9v DC power supply.
The microcontroller card has the 6502 CPU & Memory with sites for interrupt switches (NMI, RST, IRQ), the 1.006MHz crystal, circuitry for address decoding and chip selection, and (at the bottom right) an LM340T5 5-Volt regulator.
The keyboard card has a 9 digit 7 segment LCD display utilising 8 digits via a 25 key hexadecimal keypad. The rest of the card is the CUTS 300 baud cassette interface and the Euro Connector (Allowing the CPU card to be used in a System 2, 3 or 4). The rst key resets the microprocessor and starts the monitor program (which in turn initially displays eight dots, then waits for a command key to be pressed).
300 Baud Cassette
Acorn System 1 - Technical Manual
Acorn System 1 - Circuit Diagram
Acorn System Schematic Keyboard
Acorn System 1 Firmware (Mike Cowlishaw)
Acorn System 1 Emulator (Mike Cowlshaw)
