Welcome to Sam’s Microblog. Here I will be mostly rambling about vintage microcomputers and their associated technologies. I hope you will find this blog an interesting read.
On 13 May 2017, I went up to Cambridge to visit the Centre for Computing History for the Acorn World exhibit.
I took a ton of photos, which I am currently in the process of organising. I’ve made a selection of Flickr albums, which you can find below:
- Acorn System 5
- BBC Domesday System
- BBC Micro (Issue 1)
- Steve Furber’s personal prototype of the Acorn Proton (which would go on to become the BBC Micro)
Today I received my latest BBC Micro-related purchase, an ATPL Sidewise ROM board:
I decided to fit this board to the BBC Micro with the RetroClinic Datacentre installed in it, however fitting this board was not as easy of a task as I had initially anticipated.
Problem #1: The power supply
The Sidewise board requires that the power connectors be bent at a 90 degree angle in order to make room for the board. This was not a problem in the past, as the spade connectors of past power supply revisions used a softer plastic/rubber connector which could be bent easily, however newer power supplies use a hard plastic connector. Thankfully, the instruction manual that came with the unit came with an addendum covering this scenario. The solution is to cut a notch into the spade connector and carefully bend it round. The manual with the instructions on this process, as well as general fitting instructions, can be found on Retro-Kit’s website here.
Problem #2: CombiROM
The next problem came when I booted up the machine for the first time. I was greeted with a message that simply said ‘Language?’, meaning that the system cannot find the BASIC language ROM.
After some further testing, I narrowed the problem down to the use of the RetroClinic CombiROM for the language. From what I’ve found online, it seems that this ROM contains the BASIC language and ADFS. I believe it also contains RamFS, but there is a second chip installed which is labelled ‘CombiUtils/RamFS’, which I believe is what the Beeb uses for RamFS. I swapped out the CombiROM for a standard BASIC language ROM salvaged from an old BBC Micro (now used for parts), and the system booted up into BASIC. RamFS is being picked up in the socket corresponding to the CombiUtils/RamFS chip, but no ADFS.
My theory is that the Sidewise board cannot handle this combination of ROMs in one chip, but I could be wrong. I believe that I can get ADFS back by fitting the CombiROM chip back into one of the on-board ROM sockets, however I haven’t tried this yet.
Update (7 May 2017): No joy with installing the CombiROM chip into the on-board ROM sockets. After switching into DFS using the *DISC command, typing *XADFS causes the Beeb to hang.
Update (5 June 2017): I have managed to re-gain access to the ADFS drive by burning a copy of ADFS 1.33 to an EPROM and installing it in the system. Hooray!
I have decided to resurrect this blog from an old backup I found, which I’m hoping to expand on in the near future. There may be the odd broken image here as a result of the import process, but I hope to have them sorted soon.
I bought a job lot of three Acorn A7000 computers from eBay, all in various states of disrepair. The pictures on the auction weren’t that clear, so I was taking a bit of a gamble on what sort of condition these were going to be in. So far, it’s been a fairly bitter-sweet haul of goodies.
The best condition of the lot was the first one, which came without a power supply, drives or RAM, very bare bones. The motherboard on this one is in very good nick, with a minimum of corrosion damage, which is so common in these computers.
The second one comes with a power supply, floppy drive and motherboard. Again, the RAM, hard drive and CD-ROM drive were not included. This one doesn’t have a CMOS battery in it at all, and had a few dabs of hot glue in places. I tried to boot this one up, however so far I haven’t had any joy with it; there’s no beep when you power it on, although the monitor does respond (albeit with an “out of range” error).
The third one was a pleasant surprise, in that it was an Acorn A7000+ rather than a A7000. This one came complete, with RAM and a hard drive. The only problem is, the motherboard is badly damaged by corrosion. I’m going to try giving it a bit of spruce up with some contact cleaner and pray that none of the tracks have been damaged. Sadly, however, I don’t think that’s the case.
I’m confident that I can get at least one working A7000 out of this bundle.
It’s been a long time since I’ve updated this blog, but I have finally got round to writing a page about a rather obscure computer that I picked up a year ago, the Philips P3202-342:
I bought this computer from eBay in January 2014, and I have now written a full page about it, which you can read here.
I was saddened to hear the news this morning that Ian McNaught-Davis had passed away at the age of 84. He was best known for presenting The Computer Programme, Making the Most of the Micro and Micro Live in the 1980s. He was also president of the UIAA (International Mountaineering and Climbing Foundation) for nine years between 1995 and 2004.
Although I wasn’t around in the 1980s at the time of the original broadcast of his programmes, the programmes that he presented were the first place I looked to learn more about the BBC Micro when I started becoming interested in them a few years back. He was such a wonderful presenter, and was one of the driving forces behind my interest.
Today I received an item that I have always wanted for my still-young Acorn computer collection:
I purchased this towards the end of January 2014. The only problem is it seems that one of the capacitors in the power supply has blown, as the seller said he plugged it in and it started emitting horrible electrical smells. This is similar to what happens to a lot of BBC Micros after around 20-30 years. Replacing the capacitors in the Beeb’s power supply is something of a rite of passage for an Acorn collector, so I’m hoping that it’s a similar problem with this 6502 second processor. The theory goes I should be able to get it working again by changing the capacitor which failed in the same way that one does to a BBC Micro.
I briefly opened up the processor to see if there was something glaringly obvious wrong with the power supply, but this first glance of the processor proved inconclusive. There is definitely quite an unpleasant smell reminiscent of a failed BBC Micro power supply, though. If all else fails, I believe that these can be run with a BBC Micro power supply, but ideally I want it to all still fit in the original box.