The 6502 processor Eurocard (100 x 160 mm) has crystal control 1K bytes of RAM and 512 bytes PROM containing a system monitor. A second Eurocard is mounted above it using pillars the two are connected by ribbon cable. The top card has a click action 25 key hexadecimal keyboard and an eight digit seven-segment LED display. The system monitor contained in two fusible link PROMS(74S571) is very easy to use and provides the following facilities using one of the 8154 devices as a keyboard interface and display driver. RESET, MEM0RY ALTER AND EXAMINE, GO RESTORE, allows continuation in original evironment of program after break BREAK POINT INSERT/REM0VE allows setting and cancellation of break point anywhere. SAVE 10 TAPE - transfers memory ccntents between given locations on the tape. LOAD TO TAPE - loads data into locations specified by the first two bytes on tape. The monitor also includes a character font for seven segment representation of the complete ASCII. character set. The system 1 is prcvided 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 progran a step by step intrduction to machine code programming complimented by 16 original applications programs. CODE DESCRIPTION PRICE 335 Acorn system 1 users manual 5.00 1100 Acorn system 1 including manual) 79.00 1105 System 1 RAM i/o CHIP 8154 9.00 1110 System 1 mains adaptor 7.00