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Vintage computer fun

david ellwood said:
easiest way is to snip the pins close to the body of the chip and then pull them out one at a time. Then clear the holes with braid.

I have a desoldering station but would still do it this way unless I needed to not destroy the chip.
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Yes, once it occured to me that I really don’t care about saving the chips at all (one of the most likely candidates is only a quid) and that takes the fear right out of it. I know I can deal with standard thru-hole component desoldering/resoldering, and this reduces multi-legged chips to that level. I’ll socket anything I do. I’m hoping either the (nicely socketed) 6522s do it or failing that its IC14 which is a likely candidate as it interfaces the RAM to the system bus (that’s the one that will need soldering). Beyond that I’m likely running out of my depth fast and I’ll have to get a professional to fix it. This stuff quickly gets to the point of needing a scope and really expert knowledge of the Beeb. Thankfully there are several offering this service. I’m not bothered, the aim was to learn stuff and I don’t really care about the cost at all as long as I end up with a mint fully working Beeb. Its all peanuts compared to audio - lots of fun for less than a mid-priced interconnect cable in most cases!
 
Did folks see these retro gaming machines at CES - not vintage but emulated, but looks fun nevertheless...

 
My BBC B spares turned up today and the 6522s didn’t appear to be the issue as the crashing persisted after swapping new ones in. I sat looking at it for 15 minutes or so trying to decide whether I was brave enough to do my first ever proper chip replacement on a nice vintage computer I actually care about, and eventually went for it:

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I decided to sacrifice the old chip as it is only worth a quid, so I cut the legs at the top and then desoldered them one by one. Once I figured out how to hold stuff and got into a routine it was actually really easy and went without the slightest issue. I just heated the pin from the back, gently pulled the pin out, and then cleaned the holes with a solder sucker. I’ve stuck a socket in so if that chip goes again it is an easy fix. That bit was easy, I’ve no issue at all with soldering neatly and you’d not spot my work from the original now I’ve cleaned the flux off.

I’m *very* reluctant to say I’ve fixed it, but it has so far had two runs of half an hour or so and not crashed/glitched (one in bits, one now reassembled). I’ll cook it for a while and see if other issues emerge, but it was previously crashing/glitching within five minutes or so, so fairly promising. At least I have not made it any worse, and to be honest that was always my main priority! I was terrified about lifting tracks etc, but it went without issue. I don’t think I’d want to work on anything smaller than this though.

PS The top right pin hole is meant to look like that, it isn’t a missing pad, or if it is it was like that before I desoldered the chip (I have photo evidence)!
 
david ellwood said:
Looks a neat job, did you swap IC15 too?
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No, that one wasn’t on the hit list at all. I’m only scratching the surface of Beeb architecture, but as I understand it IC14 is a CPU to memory bus controller (and a very well known point of failure), IC15 I think has something to do with Teletext.

There is a great interactive map of the BBC B here, just click on a chip to get a definition.

The next suspect I’d been given (by Mark at RetroClinic) was IC45, but hopefully it is ok. Beyond that the issue would likely have been RAM, which can be very complex to diagnose.

PS Still working at about 50 minutes! It has never run this long before!
 

Here’s a fascinating old (1953) US military film on an entirely mechanical/analogue computer used for ship’s gun trajectory calculation. Amazingly clever stuff just using gears, racks, differentials, cams etc to do some complex maths on the fly. Should be of interest to anyone with any interest in the Babbage Difference Engine, Hartree Analyser etc.
 
Tony L said:

Here’s a fascinating old (1953) US military film on an entirely mechanical/analogue computer used for ship’s gun trajectory calculation. Amazingly clever stuff just using gears, racks, differentials, cams etc to do some complex maths on the fly. Should be of interest to anyone with any interest in the Babbage Difference Engine, Hartree Analyser etc.
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very nice

if you want to see an amazing piece of engineering have a look at a mechanical navigation computer ... amazing

 
I read that obit this morning. I had not heard of him before. I worked at ICL in West Gorton, the development centre, on 2900 series stuff from 1978 - 1983. Fond memories.
 
From memory I think I can remember seeing 2900 series or very similar, at my father's ICL office in Euston!
Clearer memories of the ill fated OPD series!
 
My father in law has lots of pictures and memories from the time he worked at LEO computers, their first design being a deriviative of the Cambridge EDSAC. The company also ultimately went on to be part of ICL and then Fujitsu.
 

An amusing and informative interview with Steve Furber, Chris Curry & Herman Hauser (Acorn & ARM) who’d just been forced to watch the ‘Micro Men’ drama at the Centre For Computing History! Worth a watch if you have an interest in the BBC Micro, Sinclair etc, as if course is ‘Micro Men’ which is available on the same channel.
 
Tony L said:

An amusing and informative interview with Steve Furber, Chris Curry & Herman Hauser (Acorn & ARM) who’d just been forced to watch the ‘Micro Men’ drama at the Centre For Computing History! Worth a watch if you have an interest in the BBC Micro, Sinclair etc, as if course is ‘Micro Men’ which is available on the same channel.
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Thanks for that. I'll have a look.

FWIW I've recently sent a long (audio) interview I did of Dave Walker and some other 'Acorn' people to the CCH. When I dug it out I was surprised to find it was about 3 hours long! Two full C90 cassettes. It covered all kinds of details about the things Acorn developed, and even info on their 'pantos' and how some played jokes on others.

Snag is that I've not been able to re-contact Dave. I need to find out if it is OK for the recording to be made public. Without that it may have to stay 'archive' at places like CCH. We did find a Linkedin page for him, but got no response when someone tried it.

If anyone knows what's happened to him, it would be welcome info. I'm only hoping he is still alive and well! :-/
 
The 2960 series were babies to us. The mighty dual P4 systems (2980 series) type stuff was where it was really at.

We used to play Dungeons and Dragons on the 60 series on night shifts if they were unoccupied. It was a 'test' program of course!
 
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