Name Electron

Origin U.K.

Year 1983

CPU 6502A, 1.79 MHz

RAM 32 kbytes. Some models used a single 4x64 kbit chip as memory. The ULA had to split the bytes into nibbles and put them in the right places, which effectively halved the speed of memory accesses.

ROM 32 kbytes. Like on the Acorn BBC-B, the use of banked ROMs allowed the Electron to have a lot of system software built-in. There were actually word processors and other packages which came on an EPROM. The basic system did not have EPROM sockets like the BBC B, but there were two ROM cartridge slots on an add-on peripheral.

Motherboard layout

Case Smallish white case with white keys. Rather unimpressive, compared to the BBC model B. There is a single orange LED to indicate Caps Lock
Keyboard ASCII in slightly non-standard QWERTY arrangement. The BBC B's function keys are gone. They can still be accessed using combinations of a special FUNCT key and the ten numerical keys. The same special key can be used with alphabetic keys to produce various BASIC keywords. The keywords can still be typed in the usual way, like in the BBC B. The keyboard is generally very crowded, and some symbols had to be placed in awkward places (e.g. square brackets). There is no Caps Lock key (the shift key has to be used with the FUNCT key).

Display Driven by the ULA (Undedicated Logic Array). 7 possible modes (BBC model B mode 7 is missing):

* Mode 0: 640 x 256, 2 colours. Text: 80 x 32.
* Mode 1: 320 x 256, 4 colours. Text: 40 x 32.
* Mode 2: 160 x 256, 16 colours. Text: 20 x 32.
* Mode 3: Text-only at 80 x 25, 2 colours.
* Mode 4: 320 x 256, 2 colours. Text: 40 x 32.
* Mode 5: 160 x 256, 4 colours. Text: 20 x 32.
* Mode 6: Text-only at 40 x 25, 2 colours.

The colours displayed in any mode can be freely picked from the 8 colours available (and colour switching is done a lot for fast graphics). Acorn always claimed there were 16 colours. In fact there are, but the top 8 colours are flashing versions of the other 8 ones.

Audio One channel of sound, plus one channel of white noise. Driven by the ULA (Undedicated Logic Array). The sound came out of a smallish internal speaker. There were three virtual sound channels, but all were mapped to the single available physical channel. This was done to maintain compatibility with the Acorn BBC-B.

Input/Output Minimal to non-existent. All the BBC B's I/O is missing. In its place is a wide connector which accepts an expansion box offering all the missing connectivity. So here's the complete list:

* General expansion port
* Tape player/recorder connector, 1200 baud interface.
* TV connector (RF modulator)
* RGB monitor connector