I once had a BBC Model B Microcomputer
First release 17 July 2011
Created thumbnail images 23 April 2012
This page is largely
for my own benefit, although I've written it in the hope it will be
useful to others (like
you, if you're reading this page and you aren't me).
My second personal computer -- the "BBC Model B Microcomputer"
Back in 2002 I unearthed my old "BBC Model B Microcomputer",
an impressive (in the early 1980s) 6502-based machine
made by Acorn Computers in the UK. I obtained one when
it was new, did a lot of programming on it until the late 1980s
and then hid it under a bed. While I moved house a few times over the
years, the BBC Model B stayed hidden along with all my old notes, printouts and genuine 5-1/4"
floppies. In 2002 I made a partially-successful attempt to
recover my old software from the 5-1/4" floppies, and documented my experience. (I made some good progress
until my floppies literally started falling apart
inside my old drives, clogging the heads. These floppies were around 20
old, and the magnetic particles started stripping off where the drive
touched the disk surface.) I revisited the task of recreating floppy images in 2005,
and now (2011) I have finally gotten around to documenting what I've
The BBC Model B Microcomputer
The BBC Model B Microcomputer (or just the "Beeb") was based around a
2MHz 6502 processor, had bit-mapped and Teletext graphics modes, came
16K or 32K of RAM, and supported the use of 8K and 16K ROMS to hold
languages, operating systems, and applications. The keyboard and
shared the same box, with UHF output for displaying on TV screens and
RGB output for monitors.
More detailed technical specs
(and a whole lot more) can be found at Rob Schmidt's "The BBC Lives!" website.
My own Beeb
My particular Beeb had 32K RAM, OS 1.2, BASIC 2,
Disk Filing System (DFS) 0.9E, four-channel analog to digital converter
casette interface, parallel printer port, an 8271-based disk interface
two 5-1/4" floppy drives. I had also developed and installed a
memory editor/disassembler known as OZMON. The keyboard connector was a
loose after all these years, but after a few wiggles the Beeb booted up
new! The disk drives still appeared to work, and I was able to format
read/write a blank 5-1/4" flppy. So far so good.
Emulating a BBC Model B Micro
As of July 2011 my personal favorite emulator is BeebEm 4.13 (BeebEm413.exe) -- I have utilised the Windows version of BeebEm under Windows 7 and also under PC-BSD 8.2 using Wine 1.3.21 (specifically the PC-BSD PBI for Wine) . A longer list of emulators is available at http://www.stairwaytohell.com/emulators/homepage.html as of July 2011.
Some of my own software
worked on a range of projects for my own entertainment back in the
mid-1980s. Here is a short list, with links to some binaries, source
code and/or documentation in a few cases.
- OZMON -- I wrote my own 8K ROM-based Assembler/Disassembler/Monitor.
- Very useful for inspecting, moving and
editing memory, disassembling machine code, and assembling fragments of
machine code on the fly. Notable features:
- Single stepping through machine code routines
- Reading and writing may be independently
performed on RAM, selected ROM slots, files or disk sectors. For
example, even if OZMON lived in, say, ROM slot 13 you could use OZMON
itself to read from (dump/disassemble) any othe ROM slot's contents.
- Version 1.0 was finished in 1984, version 1.1 was released in 1986 with the ability to also write to a different ROM slots (useful when editing ROM slots populated by RAM chips).
- LIFE -- Didn't everyone implement Conroy's "Game of LIFE" early in their programming career? Here is one of mine. from 1982, a mix of BBC Basic and in-line assembler.
- FORTH -- well, my own idiosyncratic variant whose main claim to fame was rudimentary multitasking.