The Acorn Eurocard systems were a series of modular
microcomputer
A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PC ...
systems based on rack-mounted
Eurocards developed by
Acorn Computers
Acorn Computers Ltd. was a British computer company established in Cambridge, England, in 1978. The company produced a number of computers which were especially popular in the United Kingdom, UK, including the Acorn Electron and the Acorn Archi ...
from 1979 to 1982, aimed primarily at industrial and laboratory use, but also home enthusiasts.
The experience gained in developing this modular system strongly influenced the design of Acorn's first all-in-one home computer, the
Acorn Atom
The Acorn Atom is a home computer made by Acorn Computers Ltd from 1980 to 1982, when it was replaced by the BBC Micro. The Micro began life as an upgrade to the Atom, originally known as the Proton.
The Atom was a progression of the MOS Techn ...
, released in March 1980; and also much of the circuitry in its successor, the
BBC Micro
The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by Acorn Computers in the 1980s for the BBC Computer Literacy Project. Designed with an emphas ...
, first shown in late 1981.
Acorn's final rack-based machine was the System 5, released in late 1982. The Eurocard business was then sold on to one of its principal resellers, Control Universal Ltd, which continued to develop various cards for industrial use based on the Acorn-standard bus during the 1980s, but ultimately went into
receivership
In law, receivership is a situation in which an institution or enterprise is held by a receiver—a person "placed in the custodial responsibility for the property of others, including tangible and intangible assets and rights"—especially in ca ...
in 1989.
Eurocards
Placing the two Eurocards from the original
Acorn Microcomputer
The Acorn System 1, initially called the Acorn Microcomputer (Micro-Computer), was an early 8-bit microcomputer for hobbyists, based on the MOS 6502 CPU, and produced by British company Acorn Computers from 1979.
The main parts of the system we ...
onto a
backplane
A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbo ...
made the system straightforward to expand in a modular way. The original I/O card, minus its keypad and LED display, became the cassette interface card; while the original
6502
The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small te ...
CPU card, slightly adapted with the addition of a keyboard interface, became the basic CPU card of the system.
A series of interchangeable expansion cards were then developed: additional RAM cards; a card containing a BASIC interpreter on ROM; a 40×25 character VDU card, and a UHF adaptor for it; interface cards; a
floppy disk controller
A floppy-disk controller (FDC) has evolved from a discrete set of components on one or more circuit boards to a special-purpose integrated circuit (IC or "chip") or a component thereof. An FDC directs and controls reading from and writing to ...
;
Econet
Econet was Acorn Computers's low-cost local area network system, intended for use by schools and small businesses. It was widely used in those areas, and was supported by a large number of different computer and server systems produced both by ...
network cards; an 80×25 character VDU card; and later also alternate processor cards, offering a
6809
The Motorola 6809 ("''sixty-eight-oh-nine''") is an 8-bit microprocessor with some 16-bit features. It was designed by Motorola's Terry Ritter and Joel Boney and introduced in 1978. Although source compatible with the earlier Motorola 6800, the ...
or a faster 6502.
System 2
The Acorn System 2 was offered as a system by
Acorn Computers
Acorn Computers Ltd. was a British computer company established in Cambridge, England, in 1978. The company produced a number of computers which were especially popular in the United Kingdom, UK, including the Acorn Electron and the Acorn Archi ...
from 1980. It was the successor to the Acorn Microcomputer (renamed the
Acorn System 1
The Acorn System 1, initially called the Acorn Microcomputer (Micro-Computer), was an early 8-bit microcomputer for hobbyists, based on the MOS 6502 CPU, and produced by British company Acorn Computers from 1979.
The main parts of the system ...
).
The system comprised four
Eurocard-sized
printed circuit boards
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich struct ...
mounted in a 19 inch sub-rack frame on an 8-slot
backplane
A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbo ...
, plus a (separately supplied) additional external keyboard. The four PCB cards contained respectively:
* a CPU card, containing a 1 MHz
6502
The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small te ...
microprocessor, the keyboard interface, and a 2K ROM with the cassette operating system (The 6502 card could be swapped for a
6809
The Motorola 6809 ("''sixty-eight-oh-nine''") is an 8-bit microprocessor with some 16-bit features. It was designed by Motorola's Terry Ritter and Joel Boney and introduced in 1978. Although source compatible with the earlier Motorola 6800, the ...
.)
* a VDU card, providing a 40×25 character
teletext
A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories
Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipp ...
-standard display, based on an
MC6845
The Motorola 6845, or MC6845, is a display controller that was widely used in 8-bit computers during the 1980s. Originally intended for designs based on the Motorola 6800 CPU and given a related part number, it was more widely used alongsid ...
CRT controller and an
SAA5050
The Mullard SAA5050 was a character generator chip for implementing the Teletext character set. The SAA5050 was used in teletext-equipped television sets, viewdata terminals, and microcomputers, most notably on computers like the Philips P200 ...
teletext character generator,
* a cassette interface card,
* a memory card with 4K of RAM and a 4K
BASIC
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
ROM. A further 4K of RAM could be added, and also an additional 4K ROM containing floating-point routines and scientific functions.
The CPU card and cassette interface card were the same cards as used the
System 1
The Macintosh "System 1" is the first version of Apple Macintosh operating system and the beginning of the classic Mac OS series. It was developed for the Motorola 68000 microprocessor. System 1 was released on January 24, 1984, along with th ...
, but with the keypad and LED display of the latter left unused. The system could be expanded with any of Acorn's standard Eurocards to add further functionality. In 1982 it was being offered for £320, or £480 with power supply, plus an additional £136 for the optional keyboard.
System 3
The Acorn System 3 added a floppy disk controller card, floppy disk drive, and disk operating system ROM, replacing the cassette interface card and cassette operating system of the System 2 machine.
The System 3 became the standard workhorse for development in the Acorn lab: the Acorn Atom has been called a cut-down version of the System 3; and it was based on the System 3 that much of the development work for the BBC Micro was done.
A minimum configuration contained:
* A CPU card
* A 40×25 Teletext-standard VDU card
* 8K RAM with 4K BASIC ROM
* A floppy disk controller
* One 100K floppy disk drive
In 1982 this was being offered for £775, or £1075 with power supply, casing, and two further 8K RAM cards; plus, again, an additional £136 for a keyboard.
System 4
The Acorn System 4 was similar to the System 3, but in a double height frame, containing fourteen slots in the lower frame, and two floppy disk drives in the upper half of the frame above them. With casing, power supply, and a basic 16K of RAM it was being offered for £1525 in 1982 (again, plus extra for the keyboard).
System 5
The Acorn System 5 was the final Acorn rack-mounted system, released in 1983. It was mounted in an extra-height single 19-inch frame, which could accommodate two vertically mounted
5 1/4-inch floppy drives, with either seven
or ten
Acorn System 5
Chris's Acorns Eurocard slots. It came complete with a power supply, and was only available fully assembled. As standard it had a 1 MHz 6502, 32K DRAM, a disk controller, and either the 80×25 or the Teletext
A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories
Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipp ...
40×25 VDU cards. Customers could choose which cards to install in the remaining slots, including interface cards, an additional 16K DRAM card, and/or an Econet network adapter; they could also choose to upgrade the processor board to a faster 2 MHz 6502 board.[Acorn catalogue, including the System 5](_blank)
1983 /ref>
References
External links
The Acorn Atom pre-history
{{Acorn_computers
System 2
6502-based home computers
Computers designed in the United Kingdom