- (modify) Memory display and modification
L (load) Reads a block of bytes from tape
X (go) Run program starting at an address
R (return) Resume after a breakpoint
P (point) Inserts or removes breakpoint
S (store) Writes a block of bytes to tape
(up) Increment displayed address
(down) Decrement displayed address
* CPU: 6502 1 Mhz
* RAM: 1 kb
* ROM: 512 bytes
* Text Modes: 8 x 1 (8 digits seven-segment LED display)
* Graphic Modes: None
* Colors: None
* Sound: None
* I/O Ports: Eurocard bus (100 x 160 mm cards), Tape interface (300 bauds), RAM I/O (16 lines I/O)
* Keyboard: Calculator-style hexadecimal keyboard, 25 keys
* Built In Language: Machine code
* Peripherals: Memory expansion boards (4k / 8k), Video card, 4k Basic card, Assembler/Disassembler card
This system requires full keyboard emulation to work correctly. At startup, full keyboard emulation mode is enabled by default. Whilst in full keyboard emulation mode, some key associated functionality may be disabled (like the ESC key for EXIT). The keyboard emulation mode is toggled using the "Scroll Lock" key (by default).
Original Keyboard: Hexadecimal keyboard, 25 keys
c d e f m l
8 9 a b g r
4 5 6 7 p up
0 1 2 3 s down
The emulation of this system is Preliminary.
History and Trivia
This 6502 modular system was the first computer produced by Acorn in 1979. It was basically the same type of computer as competitors offered at that time (KIM-1, MK14, Nascom, etc...) : a 6502 or Z80 CPU (in this case, a 6502) mounted on a simple "naked" board, with a one-line display and a hexadecimal keyboard.
The System 1 is no exception : it featured an eight-digit seven-segment LED display, a hexadecimal keyboard (25 keys) and as there was no built-in BASIC in the computer, it had only machine-code.
Fortunately there was a tape-recorder interface communicating at 300 bauds.
Like all these types of "hobbyist" computers, the main advantage was the expandability of the system. They were quite cheap machines because they were shipped basically "naked". Then you had to buy whatever cards you wanted (video, BASIC, sound, etc...). Here the system was Eurocard compatible, which was a well-known expansion board standard at that time.
If then you had "too many" expansion cards, a Eurocard rack was available to organise the whole system.
The System 1 itself was composed of two Eurocard boards (one for the CPU and the other for the keypad and display) mounted one above the other (sandwiched, you could say), the two being connected by a ribbon cable.
(info from old-computers.com)
* Mike Cowlishaw's Acorn Microcomputer Page -- http://www.cary.demon.co.uk/acorn/index.html
* Acorn System 1 at old-computers.com -- http://www.old-computers.com/museum/computer.asp?c=483
* Mike Cowlishaw's Acorn Microcomputer Emulator -- http://www.cary.demon.co.uk/acorn/acornEmulator.html