Vintage Acorn

Mighty Oaks Grow From Small Acorns

Cookie Policy            Privacy Policy           Copyright            Terms & Conditions           Contact the Team

Acorn System 1

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).





Specification
Part No.
Motherboard 200,000; Keyboard 201,001
CPU
Moss Technologies MPS 6502
CPU Clock
1.006 MHz
RAM
1.125 KB (Two 2114 Static RAM 1024x4bit & INS8154N 128 Bytes [Reciver & Driver])
ROM
512 Bytes (Two 74S571 PROM 512x4bit)
Firemware
Machine Code
Power Consuption
2.7 Watts
Graphics
8 Digit 7-Segment Display
Keypad
25 Keys (16 Hex, 8 Command, 1 Reset)
I/O
Computer Users Tape Standard
300 Baud Cassette
Price
£70.20 (1979)
Acron System 1 Keyboard Keys
m
(Modify) memory display & modification
l
(Load) reads a block of bytes from tape
g
(Go) run program starting at an address
r
(Return) resume after a breakpoint
p
(Point) inserts or removes break point
s
(Store) writes a block of bytes to tape
^
(Up) increment displayed address
v
(Down) decrement displayed address