The System 1 was the first commercially available computer produced by CPU Ltd under the trading name of Acorn Computers Ltd. It was designed by Sophie Wilson and marketed as the Acorn Microcomputer in 1979.
The System 1 consists of 2 Eurocards each measuring 100 x 160mm. The first is the 1MHz 6502 CPU card and the second is the System 1 keyboard card. They are connected together by a ribbon cable.
The CPU card has a 1Mhz crystal and a Rockwell R6502P CPU. It has 2 x NatSemi INS8154 RAM I/O chips, with receivers and drivers for the keypad ribbon cable and the other for the EuroConnector (this allows the CPU card to be used in a System 2, 3 or 4). There are 2 x 2114 providing 1KB of RAM and 2 x 74S571 ROM chips giving 512 Bytes of ROM. There is an empty socket for an 2516 UVPROM and the power connector with a 5V regulator.
The keyboard card has a 9 digit 7 segment LED display (of which only 8 digits are used), and a 25 key hexadecimal keypad. The rest of the card is the CUTS (Computer Users Tape Standard) 300 baud cassette interface.
The Acorn Microcomputer would later be developed into the System 2, 3, 4 and 5.
You can read the original article at Acorn System 1