My Old BBC Micro

After a trip “down south” I recovered by old BBC from the loft recently.

It started life as a Model A and was then upgraded to a B, and later a disk interface was added. It also has a big “Sidewise” ROM/RAM board fitted. (My dad was an IT manager for British Gas and was a big believer in upgradability. He approached buying and owning a home computer with about the same attitude as procuring a mainframe for BG. To be totally fair, that strategy did work very well. We got a huge amount of use out of the Beeb over many years.).

Anyway, it’s somewhat dirty but the plastics are in good condition. It’s quite an early board with plenty of factory bodges – the most exciting of which is a variable capacitor trimmer on a bit of veroboard randomly above an IC. The original OS was 0.1, but it was upgraded to 1.2 when that came out.

After replacing the usual suspects in the PSU and reseating the expansion board (a problem I remember back in the day) it came straight back to life. Looking at the bodges it’s surprising it worked at all, never mind after all this time. The Cub is a recent purchase BTW, back in the day we had a Philips portable TV with RGB input on the back.

Quite a few ROMs in it – some even legitimate (ISO Pascal, Wordwise). I don’t remember how Basic got upgraded to Basic 2. The more unusual ROMs uinclude PHX (Phoenix) which was a special terminal emulator used by Cambridge Uni and a few others in the UK. It implemented a page editing protocol. I have an odd personal connection to that as I ended up making the official port of the protocol to the Mac 68k era. SSMP is some other kind of terminal emulator (not the messaging protocol), but I don’t remember what I used that for.

Disks and disk drive are currently MIA – possibly still at my dads.

BBC Micro on MISTer

During Covid-19 lockdown one of the things I wanted to do was to revisit some of the old computers I used. I don’t really have the space or inclination so collect the original hardware, so I decided to try out what emulation options exist now.

I have been interested in trying some ASIC based projects, so a natural choice seemed to me to use the MISTer platform. This is a retro computer, console and arcade emulation system based on the DE-10 Nano FPGA development board. This MISTer project was developed from the earlier MIST project which used an older development board.

To get started with MISTer you just need the DE-10 Nano board, but I also chose to get the MISTer add-on board, mostly for the secondary SD Card (more on that later). Most of the emulation cores, but not the BBC Micro, need a RAM add-on board too.

Once you have the DE10 you can just flash the MISTer core on to an SD Card and boot it. You will also need a USB keyboard connected to the “USB to go” socket.

Some useful keys:
CTRL-F11   Break (BBC Micro)
F12        Load MISTer menu

One limitation of the current core is that it doesn’t support split-mode games like Elite and Revs.

Using BEEB.MMD

The BBC Micro core uses files in “MMB” format. This was a format originally developed for a BBC Micro add-on that connects SD cards to the user port and makes it look like a virtual set of disk-drive. The MMB file is a bundle of hundreds of BBC floppy disk images. Using commands on the BBC Micro you can choose to mount the images from the file in to virtual drives.

The BBC core offers two ways to mount the MMB file. If you have a secondary SD card then format as FAT32 or FAT16. Copy the MMB file as “BEEB.MMB” on to the card. The core will automatically pick up that card. In this mode the file can be both read and written.

The alternative is to rename the file as “.VHD” and copy it to the “games/BBC Micro” directory on the main SD Card. If it is called “boot.vhd” then it will be automatically loaded. If not then you can manually load from the MISTer menu. In this mode the file is read only. To unmount a previously mounted VHD (e.g. to go back to the secondary card) press backspace when picking the VHD.

There are various utilities to manipulate MMB files on PCs. I used “MMBReader” which is available on the stardot forum. On the emulated BBC Micro the MMB file is accessible using MMFS. Note that if no MMB file is available then MMFS will stall the boot of the BBC Micro by displaying the message “CARD?”.

Some useful MMFS Commands:
 *DCAT [start #] [end #]   - List disks in the MMB file
 *DIN [Drive #] <Disk #>   - Mount disk in the specified drive (default 0)

Most of the MMB files you will find on the web are pre-loaded with many original games. By default they boot in to a menu to pick the games. You can disable the autoboot on the first disk by using the command *OPT 4,0. If you subsequently want to run the boot use *EXEC !BOOT.

Grid Runner – BBC Micro Juvenilia

My first computer was a BBC Micro Model A (early version with the linear PSU and bodge wires on the circuit board). Later we upgraded it to a Model B. I loved it, and even took it on holiday a few times (!) My parents must have been very understanding.

I was amazed today to discover that the BBC Micro community has saved two very obscure games I wrote in my teens and you can now play them in the browser:

Grid Runner

http://www.bbcmicro.co.uk/game.php?id=636

Grid Runner II

http://www.bbcmicro.co.uk/game.php?id=765

IIRC selling Grid Runner was the first money I ever earned. The BBC Micro magazine Beebug (which was based close to where we live) included it in a demo disk (image via a kind user of the StarDot forums).

In case you are wondering, I am not colour-blind. The clashing colours were inspired by the BBC classic game Frak.

JS Beeb is fantastic BTW.

Everyday Electronics Magazine

Everyday Electronics magazine is something I have fond memories of from my childhood. Much of the practical knowledge I have of electronics originated from things I read there or stuff I tried to make (some of it DID work). For many years my parents kept-up a subscription for me until sometime in the late-80s when I outgrew it.

There is quite a lot of info online about EE’s sister publication Practical Electronics (which it would eventually merge with to create Everyday Practical Electronics) but I can’t find a lot written about EE. Recently I saw an edition of EE that recognised as one I originally owned in a second hand shop. At 20p it was an easy decision to take home.

EE always put a bit of effort in to the cover which is one thing that makes them memorable. This one with the dodgy looking vicar and his assistant is perhaps memorable for the wrong reasons. The projects are typical of what I remember – endless variations on simple circuits with oscillators, discreet transistors, 4000-series CMOS and op-amps. Even the cover project isn’t that exciting, though if you were in the market for an electronic wheel of fortune I guess it would do the job. They might have been basic and (whisper) not terribly useful but building them was still a great way to learn practical skills.

The features are quite interesting and remarkably well considered in terms of content. Magazines like EE were the main source of information in the pre-Internet era and you can almost see how the different features mirror popular Internet content today. In “For Your Entertainment” Barry Fox makes some interesting comments on the current state of flat-screen displays before getting side-tracked in to a discussion of Sinclair’s doomed flat CRT project. The government didn’t half invest in some rubbish projects in those days. Some of the features do hint towards the tide of consumer electronics that would spell doom for much of the old hobbyist world. Another glimpse of the future is the side-bar on direct broadcasting by satellite in “Radio World”. The introduction of DBS as a platform for Sky TV was a huge step towards today’s media landscape.

As a child, my favourite regular feature became “Counter Intelligence” by Paul Young. I liked his witty, caustic and grumpy musings on life in the kind of corner electronics shop that was already finding times tough. I remember that dad used to take me to a shop in Leicester staffed by blokes in beige lab-coats stocked with thousands of components in tiny draws. They hardly ever had exactly what you wanted but could usually produce something that would do the job.

The adverts are a real blast from the past. Many of them seemed to run unmodified for years and years. The spiv zapping his light and the odd boy with his crystal set were almost permanent features. I imagine J Bull (Electrical) always doing deals on vast lots of unwanted items and then finding enticing descriptions to sell them off to the unsuspecting.

So, for anyone who, like me, wants to wallow in nostalgia, or just see what the old days were like here is Everyday Electronics August 1981.