Just got a BBC Micro, Model B, And I have questions

[DistantStar001]

So like the title says, BBC Micro, Issue 4, Model B.

So far the computer is working as expected. Boots to BASIC, and seems to have OPUS DDOS 3.45 installed. If someone could tell me what that is, it would be appreciated. I had to partially recap the PSU (some bulging capacitors and a little leaking but nothing serious). I'm in the States, but I've decided (for the moment) to leave it at 250v. I have a step up transfromer, os it's not a problem.

Overall, the exterior of the computer is in pretty fair shape. No chips, or scratches. It was missing all its case screws but I found some suitable replacements. However, the vinyl on top is cracking and chipped along the right side of the keyboard and the user-ROM slot has been punched out. Question: Is there anyone who makes a suitable replacement? I could fashion one, but I'd lose the labeling for the lights.

Inside it has a Sidewise board (not entirely sure what's on it) which is attached to two switches on the back. As to what thiose switches do... I have no idea, as switching them up or down doesnt seem to do anyhting. This leads to my next question: Would the Sidewise interfere with the User-ROM? I was considering adding a ZIF Socket (to plug the hole if nothing else), but I wanted to know how functional that would be? I've also seen an edge connector, but I have no idea why or what functio it would serve?

Additionally, there's a spot below the keyboard where I've seen some people (pictures and YouTube videos) where people added dip switches but they never explained why? Is ther any utility or advantage to having these switches?

Also, there's what I'm guessing is a double-density(or 2-sided) floppy board installed. But I know how proprietary the drives are? If I could get the right connector, could I adapt a standard PC drive? I also have a drive for a TRS-80 and Apple II, though I doubt that the latter would work. At some point, I was going to get an SD solution, but floppies can be fun too. Basically, what kind of drive do I need, and can I adapt one that I have?

My next question regards ECONET. I know nothing about it (other than it was used to distribute software in a classroom enviorment with limited access to floppy drives). At the moment, my computer doesn't have it installed, but I was thinking of adding it. But what are the advantages and limitations? Can I use it to network to other non Acorn 8-bit micros? Or am I limited to other BBCs? Can I use it to connect to outside servers? I understand these things can still connect to the BBC News feeds, but I'm not sure what I would need to do it?

Lastly, is there anything else I should be looking into? Games? Accessories? Upgrades? Other add-ons that might be fun to play with? Any advice would be appreciated!

 

[FishFinger]

I'm not familiar with the Sidewise board, but it's most likely some additional ROM sockets - the BBC architecture supports up to 16 option ROMs, but the PCB only had sockets for four, and add-on PCBs providing extra sockets were common. The board might also have extra RAM, mapped to appear as ROM sockets but with the ability to load ROM images into the RAM from disk. The switches are perhaps for disabling the board and/or write-protecting the RAM.

The ZIF socket to the left of the keyboard was originally part of the speech synth option. The speech synth came with a TMS5220 synth chip and a speech ROM containing several dozen words recorded by a BBC newsreader. The kit also included an edge connector socket that mounted next to the keyboard for plugging in small cartridges containing additional speech data. However, Acorn never ended up releasing any of these cartridges, so the socket was redundant. Some third-party upgrades fitted a normal ZIF socket there instead, attached to a cable that plugged into one of the option ROM sockets in the lower right corner of the board. This would allow option ROMs to be fitted and swapped easily without opening the case every time.

The keyboard PCB has space to mount an 8-way DIP switch to the right of the spacebar. These only let you change a few basic things - the screen mode the computer starts in, the step rate of the floppy drive, and (iirc) whether the computer tries to boot from the network or floppy first.

Econet was not all that common. I'd say >90% of BBCs sold didn't have that option fitted. It's not really useful for anything except communicating with other BBCs. It was available on some later Acorn Archimedes machines as an option but that's pretty much it.

 

[FishFinger]

I forgot to mention the floppies...

Floppy drives on the BBC are generally the common Shugart type and it shouldn't be hard to find something that will work, the TRS-80 drive may work but it might need a few jumpers changing. The official BBC floppy option used an Intel 8721 controller that only supports single-sided 5.25" drives, with a hack to make double-sided drives appear as two separate disks. The 8271 was obsolete and hard to find even at the time, and most third-party disk kits used a different chip instead, generally supporting double-sided drives and higher capacities. You have Open DDOS fitted, so it's probably a third-party Opus disk PCB you've got. If so then have a read of this page to work out which version you've got and what it can do: https://beebwiki.mdfs.net/Opus_DDOS#Hardware

 

[G7VFY]

BBC computer disk operating systems tend to treat each disk surface as a different drive . So two, double sided drives would be drives 0, 1, 2 and 3. Under CP/N their clone of CP/M this becomes A, B, C and D.

The best website for Acorn computers is called stardot.org.uk (corrected ty!)

When the BBC computer was launched, to access disk drives you need the Acorn Disk Filing System kit. It used the obsolete intel 8271 single density disk controller chip and was out of date even Acorn started using it. There were lots of 3rd party alternatives, including a mixture of single and double density, with varying levels of compatablility. I used to work in a computer shop in the 1980's and we sold them.

 

[SiriusHardware]

A minor correction, G7VFY's link above goes to a dubious placeholder web page which is obviously phishing for people's email addresses. I have no doubt this was due to an innocent typo on G7VFY's part.

The correct web address is:

stardot.org.uk

 

[DistantStar001]

I'm not familiar with the Sidewise board, but it's most likely some additional ROM sockets - the BBC architecture supports up to 16 option ROMs, but the PCB only had sockets for four, and add-on PCBs providing extra sockets were common. The board might also have extra RAM, mapped to appear as ROM sockets but with the ability to load ROM images into the RAM from disk. The switches are perhaps for disabling the board and/or write-protecting the RAM.

Sound reasonable. Also explains the battery (Really need to remove that).

The ZIF socket to the left of the keyboard was originally part of the speech synth option. The speech synth came with a TMS5220 synth chip and a speech ROM containing several dozen words recorded by a BBC newsreader. The kit also included an edge connector socket that mounted next to the keyboard for plugging in small cartridges containing additional speech data. However, Acorn never ended up releasing any of these cartridges, so the socket was redundant.

Good to know, but what a weird spot for a carttidge slot!

Acorn never ended up releasing any of these cartridges, so the socket was redundant. Some third-party upgrades fitted a normal ZIF socket there instead, attached to a cable that plugged into one of the option ROM sockets in the lower right corner of the board. This would allow option ROMs to be fitted and swapped easily without opening the case every time.

Interesting. And from what you're describing the socket wouldn't interfere with the Sidewise. Actually, from the sound of it, the socket could be wired to the Sidewise board directly if I wanted. But this leads to another question: What was supposed to be mounted to the keyboard PCB itself?

The keyboard PCB has space to mount an 8-way DIP switch to the right of the spacebar. These only let you change a few basic things - the screen mode the computer starts in, the step rate of the floppy drive, and (iirc) whether the computer tries to boot from the network or floppy first.

Could be useful.

Econet was not all that common. I'd say >90% of BBCs sold didn't have that option fitted. It's not really useful for anything except communicating with other BBCs. It was available on some later Acorn Archimedes machines as an option but that's pretty much it.

So basically useless, unless I have a second BBC or Achimedes.

Floppy drives on the BBC are generally the common Shugart type and it shouldn't be hard to find something that will work, the TRS-80 drive may work but it might need a few jumpers changing. The official BBC floppy option used an Intel 8721 controller that only supports single-sided 5.25" drives, with a hack to make double-sided drives appear as two separate disks. The 8271 was obsolete and hard to find even at the time, and most third-party disk kits used a different chip instead, generally supporting double-sided drives and higher capacities. You have Open DDOS fitted, so it's probably a third-party Opus disk PCB you've got. If so then have a read of this page to work out which version you've got and what it can do: https://beebwiki.mdfs.net/Opus_DDOS#Hardware

Good to know!

BBC computer disk operating systems tend to treat each disk surface as a different drive . So two, double sided drives would be drives 0, 1, 2 and 3. Under CP/N their clone of CP/M this becomes A, B, C and D.

The best website for Acorn computers is called stardot.org.uk (corrected ty!)

When the BBC computer was launched, to access disk drives you need the Acorn Disk Filing System kit. It used the obsolete intel 8271 single density disk controller chip and was out of date even Acorn started using it. There were lots of 3rd party alternatives, including a mixture of single and double density, with varying levels of compatablility. I used to work in a computer shop in the 1980's and we sold them.

A minor correction, G7VFY's link above goes to a dubious placeholder web page which is obviously phishing for people's email addresses. I have no doubt this was due to an innocent typo on G7VFY's part.

The correct web address is:

stardot.org.uk

Thanks for this!!! Looking forward to checking them out.

 

[G7VFY]

There are lots of technical books for the BBC micro and Acorn electron.

The manual that came with the BBC micro was two inches thick, and originally contained a copy of the circuit diagram. There was, and is a huge cottage industry built up around the BBC micro and Acorn electron. Just avoid the titles like '30 games for the BBC micro etc' as they were junk then and worthless near 40 years later.

There are lots of interesting programming languages for the BBC micro (and Acorn electron).
FORTH, LISP, PASCAL, COMAL, BCPL (A forerunner to 'C' )and I think FORTRAN.

 

[G7VFY]

 

[DistantStar001]

Are any of these available in PDF form?

 

[G7VFY]

I don't know. I am sure you know how to Google. I have the originals.

 

[mark0x01]

This is a good place to start Chris's Acorns
There are lots of links to everything Acorn & BBC related.

 

[jltursan]

Archive.org is also a BIG source of all these old manuals...

 

[G7VFY]

I bought a BBC computer and drive drive yesterday. I am going to try the disk drive on my TRS-80 model1 level-II. The bbc computer needs new filter caps and probably electrolytics too. I just thought I'd mention it.

 

[cwathen]

I bought a BBC computer and drive drive yesterday. I am going to try the disk drive on my TRS-80 model1 level-II. The bbc computer needs new filter caps and probably electrolytics too. I just thought I'd mention it.

Filter caps are a weak point on BBC Micro PSUs (then most are around 40 years old by now!) but apart from that they're pretty robust. All of mine have had new filters, and I think I changed a couple of the smaller electrolytics but that's it. The drive I have for it is Cumana-branded and was sold specifically as a BBC drive but it's literally just a half-height PC-style mech in a metal box with a power supply, no other circuitry in it at all, that's with the original Acorn controller fitted. Pretty sure it is standard Shugart signalling on the drive connector and many drives can be made to work with it.

Re. Econet as asked by the OP, worth nothing that you can't just connect two machines together with a cable. At minimum you will need a clock box and a machine to act as a server. The easiest to set up implementation without much investment in hardware is a level 1 fileserver, but that's just a resource sharing solution so several machines could share disk drives and printers; you'd essentially just end up with network attached storage rather than any sort of meaningful network between the machines. It's also very uncommon to find Econet fitted examples.

Almost all BBC Micros with Econet were installed in secondary schools which very quickly outgrew the limitations of Econet and BBC Micros in general - my school had an Econet network installed which I don't think even made it to the end of the 80's before being ripped out. Although standalone BBC Micros continued to be used long after that, generally Econet-fitted machines didn't have a floppy controller fitted which pretty much ruled out them being pressed back into service as standalone machines (unless you were happy only using them with cassettes which schools generally were not). End result is the vast majority ended up in store rooms for a few years before being thrown on skips in the early 90's. Most of what is still around today never had Econet fitted.

 

[Gary C]

We have 12 operating bbc's and the RIFA caps have failed on every single one. I just remove them. Never had an electrolytic fail though.

The assembly language manual above is an essential. The assembler built into the basic interpreter is easy to use and is a great intro to the 6502.