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
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).