Slashdot Mirror
UK's National Computer Museum Looks For Help Repairing BBC Micros
tresho writes: 1981-era 8-bit BBC Micro computers and peripherals are displayed in a special interactive exhibit at the UK's National Museum of Computing designed to give modern students a taste of programming a vintage machine. Now, the museum is asking for help maintaining them. "We want to find out whether people have got skills out there that can keep the cluster alive as long as we can," said Chris Monk, learning coordinator at the organization.
"Owen Grover, a volunteer at the museum who currently helps maintain the cluster of BBC Micro machines, said they held up well despite being more than 30 years old. The BBC Micro was 'pretty robust,' he said, because it was designed to be used in classrooms. This meant that refurbishing machines for use in the hands-on exhibit was usually fairly straightforward. 'The main problem we need to sort out is the power supply,' he said. 'There are two capacitors that dry out and if we do not replace them they tend to explode and stink the place out. So we change them as a matter of course.'"
"Owen Grover, a volunteer at the museum who currently helps maintain the cluster of BBC Micro machines, said they held up well despite being more than 30 years old. The BBC Micro was 'pretty robust,' he said, because it was designed to be used in classrooms. This meant that refurbishing machines for use in the hands-on exhibit was usually fairly straightforward. 'The main problem we need to sort out is the power supply,' he said. 'There are two capacitors that dry out and if we do not replace them they tend to explode and stink the place out. So we change them as a matter of course.'"
For my hardware class, I brought it in, took it apart and handed the chips around the class. At the end, I reassembled the whole thing and booted it back up. Fun little presentation. That old hardware could really stand up to a lot of abuse.
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
... is childs play to anyone with a decent soldering iron, solder wick, flux, and one of those spring loaded vacuum solder suckers to clean out the hole (and a little practice!).
Here's how I do it:
Melt one lead of the capacitor at a time, pulling (axial) or wiggling (radial) the capacitor from each side. Sometimes if it's really uncooperative (usually if capacitor is in a bad place to get at) you might try solder wick with flux on it, and try to suck out the solder that way.
Once the capacitor is out, check if you can fit the new capacitor leads through the holes. If not, use a soldering iron on one side to heat, and have a buddy on the other side to use the vacuum tool. Hold the iron on until the solder's melted, and without removing the iron, use the vacuum tool and in one or a couple tries it usually clears it out fine.
Putting the replacement capacitor in is dead simple to anyone that's done through-hole soldering... really if you can't get this skill down first, don't try the previous stuff (practice on some cheap electronics kits).
Main thing to watch for is applying heat for too long to the point that the varnish burns or traces start to lift. But on older boards, it's usually leaded solder so melting temperatures aren't that bad. Just make it a goal to work as quickly as you effectively can once the heat is applied.
There's tons of old motherboards and power supplies and stuff from the Capacitor Plague to practice on.
Again, this isn't the hard part of repairing electronics. The hard part is when the problem isn't capacitors and some actual thinking is needed to locate the problem (and *this* is where domain specific knowledge and tricks can come in!)
There is a fairly healthy C64 community, including electronic engineers and tinkerers, who have been able to build replacement power supplies for the good ol' breadbox given that it had particularly ugly power supply issues as well.
I don't think it would be too difficult to ask them to take a look at the BBC Micro to see what could be done there....
READY.
PRINT ""+-0
Emulators are ten-a-penny, here's one which works in your browser: http://bbc.godbolt.org/ The point of the exhibit is to provide the full tactile 80's microcomputer experience.
Yes, and they could copy the Mona Lisa so everyone could see it up close.
systemd is Roko's Basilisk.
Damn, just when my points expired.
Loved that machine, and can still hear that boot-up sound.
Pity the 64 beat it hands-down on graphics - the BBC was way more advanced on the OS side, and the built in BASIC was actually a decent structured language you could do real stuff in.
sudo ergo sum
IO ports. The Beeb had millions of them, and they were used in education too. At school I wrote programs for light-sensing diodes for instance, which were just plugged straight in.
I have a BBC emulator and it's good. It truly isn't the same thing as using the real hardware though - even simple stuff like the feel of the keyboard. I have vice64 and use it to emulator the C64, but I also have a real C64 sat in my retro-cupboard all set up and ready to go. That cupboard contains a monitor/TV, C64 with 1541 snaildrive; datasette and Commodore mouse; a Gamecube and then baby-of-the-bunch Wii. Of those the Gamecube and Wii are most easily replaceable in feel since they were operated entirely through controllers, and so long as you still use the controllers a full-screen emulator will give you pretty much the same experience. The C64 emulator will not, purely down to things like key layout, keyboard feel, SID bugs making each chip unique etc.. A BBC emulator won't give you the same feel either. Both will do well, but it's not the same.
Right. And if you want to go for a nice drive in the countryside, you just boot up a car game, right?
Emulators can be useful in many ways, but they can not replace the real thing.
virtualization is the solution. if it fails, just make a new copy.
now we need to go OSS in diesel cars
and today's programmers would feel it is more real if they are working with virtual instances ... that or a 3-d printed copy.
now we need to go OSS in diesel cars
Because those machines are just as old and therefore come with just as dry capacitors?
Nae king! Nae laird! Nae yurrupiean pressedent! We willna be fooled again!
... if you pay to fly me to the UK and back, parts and labour.
Buck Feta. You know what to do.
..technician back in the 80's to 90's.
:)
I can read from the various posts in this thread that you all think it's a walk in the park to fix these old 80's computers, oh boy...you guys may know a couple of common things such as dry soldering and drying capacitors, but there's a lot more to fixing those things than you might know.
One of the most common faults of the 80's was the ROM/RAM circuits, they where often clusters of 2/4/8 kilobyte ram chips (often 4164 etc.), and finding dead ones requires a couple of "old skool tech skills", one of the simplest one is the "thumb test", is one of the Ram chips very hot (you could of course use a bottle of cold-spray, I don't know what it's called in your country...but to us it was just Cold spray, this is essentially a spray that sprays super cool air because of a chemical process when in comes in contact with air, the surface will be really cold, forming ice crystals) and then you can see clearly which surface is getting hot fast. Another method is to use the oscilloscope to see if anything is out of the ordinary (you need to know how it looks as an image first, the voltage changes because of the logic communication will form an image, and if you know how it looks when normal, this is also a method we used.)
You can also use a logic tester, this is an instrument that can monitor the traffic in those logic circuits, you can set it to the speed of the actual logic (usually 1 to 20 MHz, depending on the computers speed) and see if everything is okay.
Another common flaw back then, was broken prints...over some time, these boards gets really hot, and this stretches the metal on the PCBs, and broken connections is some of the hardest things to find.
Another typical flaw is design flaw, over time...we needed to change I/O chips on certain models simply because it was so badly designed that they would eventually go bust, they where very sensitive too...so many of the DIY'ers out there who made their own Fast-Loaders/Robotics connected to the I/O ports would regularly blow these chips.
Pity I live in Scandinavia, I'd love to retire doing this
What this world is coming to - is for you and me to decide.
IO ports. The Beeb had millions of them
The are a good modern alternative (and cheaper than a BBC was, back in the day!). The LPC1768 has the same amount of RAM as the BBC and a bit more flash than the BBC had space on a floppy disk, and has analogue and digital I/O pins, as well as serial (which the BBC had with RS-423), and a few things the BBC lacked (Ethernet and USB).
I am TheRaven on Soylent News
I quite fancy the idea of programming a game for the BBC micro. I've learned so much since those days, it'd be fun to see what could be done with such a limited machine.
However, I'd want a modern text editor and git. I wouldn't want to go back to using cassette tapes or even 80KB or whatever they were disks.
I guess that probably means using an emulator, at least for the development part. With the odd check that it does work on a real machine.
There's probably a web site about this...
Actually, that's not as silly as it sounds. IIRC the Beeb's PSU produces fairly standard 5V and maybe 12V and the machine doesn't draw all that much power. I would have thought it would be quite easy to find a standard PSU of appropriate spec that could be substituted.
Being an oik I only had a Sinclair Spectrum. One of the posher kids had a BBC and IIRC you could even inline assembler inside a BASIC program.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Seems like one could make a cape for BeagleBoard or an add on for Rpi with the IO and an emulator for the BBCMicro.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
You can look up the details but the early BBC MIcro power supplies were linear and the later ones were off-line switching power supplies.
I just replaced a fried power supply from a 30 years old 8 bit computer. I used a modern ATX power supply and it works fine.
As noted earlier, the only problem is the missing -5V line, which existed in AT power supplies but was removed in ATX. But many ATX power supplies still offer the -5V line through the "reserved" pin 20 (it faces the grey wire "power good" on pin 8). If there is a white wire there, you have it.
They have. You can see it here:
https://upload.wikimedia.org/w...
"So long and thanks for all the fish."