Acorn Electron

Electron was designed to be a cheap home computer, a cost-reduced version of BBC Micro. It was designed in 1982-1983 and released before Christmas 1983. It was cheap, but there were many manufacturing problems with it, so for Christmas period not many machines were actually available. To correct technical problems, Acorn decided to use less chips - after shrinking BBC's logic to one ULA, which was a goal of Electron, they removed a ROM switching and second 16K ROM, putting kernal and BASIC to one 32K ROM chip. Electron had some graphical capabilities, but it was slower than, for example, Spectrum and had sound capabilities smaller then "gaming microcomputers" such as Atari or Commodore. It also had less RAM.
There were many problems with early Electrons. It used dedicated ULA circuit, manufactured by Ferranti, to handle most of system logic. This circuit was big, hot and had problems with proper sitting in its socket, which lead to continuous beeping problem. Later it was soldered in, so there were problems with solders.


Manufacturer Acorn

Origin UK
Year of unit 1984?
Year of introduction 1983
End of production ???
CPU MOS 6502
Speed 1MHz
RAM 32K
ROM 32K (Kernal, BASIC)
Colors: Maximum 16
Sound: 1-channel, noise, 3 virtual channels
OS: BASIC
Display modes: Text: 20x32, 40x25, 40x32, 80x25, 80x32
Graphics: 160x256x4, 320x256x4, 640x256x2
 
 

 

Media: Tape
ROM expansions with system bus
 

Power supply:

19V AC between 1 and 2.

Please DO NOT USE DC!
If you have to, limit to few seconds, maybe you won't destroy converter.

I/O: System bus,
Tape I/O
RGB, composite, RF out
 
 
 
 
 
 
Possible upgrades: With expansion boxes applied to system bus.
   
Software accessibility: Quite easy (TOSEC, sites)  

I have NO IDEA about history of my unit. It's very clean, both inside and outside. There are no traces of dust, even under PSU board. Outside it's very clean too. It takes a day or two for an experienced collector to make it such clean. The only sign of opening is a "1311" text and a square written inside with ball pen.


Contents: Starting, battery, usage Recording media Pinouts Links

Starting

The machine just boots up to Acorn BASIC in two beeps. If you hear one continuous beep, check ULA and memory first. Is ULA sitting firmly in socket? Re-seat it by removing socket lock wire, then opening metal piece.
Continuous beep + bright, distorted screen is usually cause of ULA not fitted properly in socket. ULA rarely fails in Acorns, it usually fails when something is going wrong with expansions.
If keyboard doesn't work - is the conductive ribbon in on piece? Aren't there any broken tracks?

From BASIC you're ready to work with cassettes:

CHAIN"PROGNAME" - loads program from cassette and runs it
LOAD"PROGNAME" - loads BASIC program from cassette
SAVE"PROGNAME" - explained...
During looking for programs their names are displayed. If there's an error, you can see something like:

150 PRINT?%#ESULT IS"
DATA?
REWIND TAPE

It means: "What the hell is this gibberigh thing I got?"

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Recording media

There are 3 types of files:
 - WAV - self-explainatory
 - CSW - Compressed Square Wave - use BackToLife to convert it back to WAV, use CSW Viewer to create them.
 - UEF - More sophisticated. Use FREEUEF to play/convert them, MakeUEF to make them.

Tape to PC: Record to WAV, use MakeUEF.
PC to tape: Use FreeUEF/Back To Life

TAP files should be played as typical Commodore/Spectrum TAP files.

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Important Pinouts:

RGB Pinout:

1 - Red
2 - Green
3 - Blue
4 - Sync
5 - GND
6 - +5V

 

Tape connector:

1,4 - Output
2 - GND
3 - Input
5 - N.C.
6,7 - MOTOR CTRL RELAY

Sytem bus:

 1  3  5  7  9  11 13 15 17 19 21 23 25 27   29 31 33 35 37 39 41 43 45 47 49
-==-==-==-==-==-==-==-==-==-==-==-==-==-==-X-==-==-==-==-==-==-==-==-==-==-==-
 2  4  6  8  10 12 14 16 18 20 22 24 26 28   30 32 34 36 38 40 42 44 46 48 50

Pin Name Direction Description
1 18V AC OUT 18V AC
2 18V AC OUT 18V AC
3 AC RET N/A AC RETURN
4 AC RET N/A AC RETURN
5 -5V OUT -5V DC
6 -5V OUT -5V DC
7 GND N/A GROUND
8 GND N/A GROUND
9 +5V OUT +5V DC
10 +5V OUT +5V DC
11 SND O/P OUT AUDIO OUT
12 16 MHZ OUT 16 MHZ CLOCK
13 DIV 13 IN IN Divide Signal by 13
14 CLOCK OUT Int CPU Clk 1.79 Mhz
15 /RESET IN RESET
16 /NMI IN Non-Maskable Int
17 /IRQ OUT Int Request
18 R-/W IN Read Write enable
19 D7 IN/OUT Data Bit 7
20 D6 IN/OUT Data Bit 6
21 D5 IN/OUT Data Bit 5
22 D4 IN/OUT Data Bit 4
23 D3 IN/OUT Data Bit 3
24 D2 IN/OUT Data Bit 2
25 D1 IN/OUT Data Bit 1
Pin Name Direction Description
26 D0 IN/OUT Data Bit 0
27 RDY IN Hold Bus when active
28 NC N/A Not Connected
29 SLOT N/A Key
30 SLOT N/A Key
31 A15 OUT Address Bit 15
32 A14 OUT Address Bit 14
33 A13 OUT Address Bit 13
34 A12 OUT Address Bit 12
35 A11 OUT Address Bit 11
36 A10 OUT Address Bit 10
37 A9 OUT Address Bit 9
38 A0 OUT Address Bit 0
39 A1 OUT Address Bit 1
40 A2 OUT Address Bit 2
41 A3 OUT Address Bit 3
42 A4 OUT Address Bit 4
43 A5 OUT Address Bit 5
44 A6 OUT Address Bit 6
45 A7 OUT Address Bit 7
46 A8 OUT Address Bit 8
47 GND N/A Ground
48 GND N/A Ground
49 +5V IN +5V DC
50 +5V IN +5V DC

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Links:

http://web.archive.org/web/20030403011859/http://www.landfield.com/faqs/acorn/games/ - Acorn Games FAQ
http://www.acornelectron.co.uk/p-home.php - Acorn Electron World - Games, Emulators, Information
http://www.walkerworks.co.uk/electron.html - Electron owner describes his experiences.
http://lionels.orpheusweb.co.uk/CompNyb/TechStuff/8-Bit/Electron/Electron.html - See this Electron - that's how it's expanded
http://8bs.com/ - Much interesting stuff.
http://bbc.nvg.org/ - "The BBC Lives!"
http://www.stairwaytohell.com/ - BBC Micro and others archive.
http://8bs.com/manuals.htm#manuals - Manuals for Acorn and BBC computers - You can get Electron manual here.
http://mdfs.net/ - Software for Acorn
http://web.archive.org/web/20090130090248/http://bbcdocs.com/ - Now-defunct site containing documentation.



 

 

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