The Acorn System 4 was the third in a series of 'proper' computers with screen & keyboard, they comprised Eurocard sized boards housed in 19" Vero Card Frame. The System 4 was a double height Vero Card Frame allowing the fitting of two floppy disk drives, it only came in one version: a full spec System 4A.
The System 4A comprised:
pair of 8K RAM + 8K ROM Boards (populated with 16K RAM)
14-Slot Backplane (fully populated with 14 sockets and buffers for the address bus)
6U Cased Card Frame (with 14 sets of card guides, boards fitted with front panels)
Disk Operating System (DOS) in ROM
System BASIC (including Floating Point) on disk
Optional extras:
Monitor
Network Operating System (NOS) in ROM
It only came assembled and tested (£1525)
"The System 4 is housed in a double height rack with
facilities for up to 14 Eurocards. The basic system has as standard two floppy
disk drives, power supplies, card frame buffered backplane, 6502 CPU, VDU
interface, 16K RAM and disk controller. A DOS controls both disk drives, and a
disk with utilities programs including disk copy is supplied with each system.
The system illustrated has the additional audio cassette
interface, 32K bytes of RAM and serial and parallel interfaces via the Versatile
Interface Board. Also shown are an Analogue to Digital converter, a PROM blower
for 16 pin fusible link and 24-pin UV erasable devices and an In Circuit
Emulator used in the development of other microcomputer systems.
The System 4 is not available as a kit.