The Acorn System 1

The Acorn Microcomputer, which became the Acorn System 1, was Acorn's first product.  It comprised two Eurocards: a 6502 Microcomputer and Keyboard/Display/Cassette Interface.

"The 6502 processor Eurocard (100 x 160mm) has crystal control, 1K bytes of RAM and 512bytes PROM containing a system monitor. A second Eurocard is mounted above it using pillars and the two are connected by ribbon cable. This second card is fibreglass, through hole hard nickel plated with solder resist and component identification. The nickel is used as the PCB is an integral part of a click action 25-key hexadecimal keyboard. An eight-digit seven-segment LED display is used for operator interface. The board also contains a CUTS Tape interface, the design of which includes a dual op-amp input and zero crossing detector for high reliability of data transfer.  The system Monitor contained in two fusible link PROM's (74S571) is very easy to use and provides a user interface using one of the 8154 devices as a keyboard interface and display driver:

The System 1 is provided with a Users Manual which includes an introduction to binary numbers, descriptions of the 6502 internal architecture and Acorn hardware, a listing and explanation of the instruction set and monitor program and a step by step introduction to machine code programming complemented by 16 original applications programs.

The System 1 serves as a low cost development system for the microcontroller, a self-contained computer for the home enthusiast and by virtue of its modular concept, the basis for a full scale computer with VDU, floppy disk storage etc., it also represents the simplest intelligent controller on the Econet." 

The System 1 was available as either a kit (£65) or assembled and tested (£79).  A detailed Technical Manual was provided showing how to construct it and a comprehensive User Manual showing how to operate it.

Memory Map