Tearing Down an Acorn A7000 - The Electronics Inside

Katie has come through again and sent me something wonderful to tear down. In 1995 windows and x86 IBM clones were cornering the market for home computers. But not everyone had fallen in line just yet. The Acorn A7000 was one of the last holdouts, and what an impressive machine it is!

#0:00 The Electronics Inside
#0:36 Acorn A7000
#1:07 Overview and Teardown
#10:47 Give your Feedback
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Acorn7000
Vintage PC
RISC

[robinhodson]

Acorn didn't go bust; Castle didn't buy the hardware division. There was a sharedealling issue where Acorn's ARM shares were worth more than the company, so the company had to be dissolved to release the shares. The business carried on, spun out into RISC OS Ltd and Castle Ltd, which have now recombined as RISC OS Developments Ltd.

[MAYERMAKES]

Acorn could have been todays apple. We have to thank the m for so much we now take for granted in computers.

[andye]

The two coax Ethernet systems were 10base5 thick coax, 10base2 thin coax which is the BNC that you have here, not a ring, it's a bus, each end terminated with 50 ohms. Some interface cards had termination optons, otherwise you used a terminator plug. Speed was 10 Mbps. 10Base5, ran over a longer distance (500m) This had the "node" points marked on the coax, and you drilled into the coax and used a "bee sting" connection to add an AUI module. Many interface cards had dual 10base2 and AUI interface options. The AUI was a 15 way D Type, usually with a slidelock retaining clip (nasty useless things)

Because the bee stings were all at the zero volt point of the electrical wave they did not upset the performance of the coax very much so 10base5 could run over a greater distance.

10base2 had a 185m in distance, (they decided to call it 10base2 rather than 10base1.85!)

There were no specific connection points as there were on the thick coax, but I think the recommendation was to have at least 3m betewwn each node.

As you say, breaking the coax did bring the network down, and there were several "make before break" type wall boxes that overcame this issue to some extent. (I spent far too much time finding partially pulled BNCs that killed the network!)



Andy

[philippearson]

Ah remember the Acorn 7000s well as I used to look after 13 units with VGA monitors hard drive, floppy drive, CD-Rom drive, fans and EcoNet Network cards great times in fact until about 3 years ago we still had on setup with sensors for use in the science department. Always ran like a dream never any trouble with them. Was sorry to see the last one go to recycling!

[talideon]

I've one of these. Thankfully, while there's some battery damage, it's nowhere near as severe as this. It's sitting waiting to be fixed up.

[AndrewGillard]

There were remnants of a coax-based network throughout my secondary school the whole time i was there (1998-2005). I don't think it was _ever_ in use during that time, but you'd still see random old machines on desks everywhere, complete with lengths of coax hanging from them :)
But even without the mischief you described, the network still had enough issues that a good portion of my A-level computing lessons were spent complaining about the "not-work" preventing us logging in or something - though in hindsight I suspect most of the issues were software-related.

IIRC they did also have an 802.11a deployment before later upgrading it to 802.11b (around 2002?). Not sure how I knew about the 802.11a network when my laptops only supported 802.11b/g (sometimes requiring PCMCIA cards even for that, of course!). Might have just been from chatting with our computing teachers.

They were even upgrading the wired network to use a fibre backbone, but I left for uni before I saw that in action :(

[MAYERMAKES]

you really need to try get this beauty back up and running!

[ironmaiden]

Seeing some of the Amigas battery damage this one is really really bad. I think it was only PCI graphics around that time. I don't think AGP had come about yet.

[sprybug]

I watch a lot of vintage computing guys and they've brought back to life old computers that had battery corrosion on the board. Vinegar is a good neutralizer of the acid, as with something called Naval Jelly. The acid will continue to eat away at the board and components until you get rid of it!

[StuccDude]

Token ring and terminated coax used similar connections, but different network stacks. (I is an olde)

[toleranz]

Try to save the arm chip, it doesn’t look corroded and may save another a7000. These CPUs are rare by now. Most of the small chips are only bus drivers and latches and the multiIO controller by smc which were mass produced and are a dime each on eBay. Such a resin table thin makes no sense in my eyes if it’s nothing special like all different acorn RISC motherboards from the first to the last together. But they should at least be optically OK, even if not functional.

[robinhodson]

That add-on network card is worth a fortune: CJE would snap that up.

[SeanBZA]

Well, if you are going to make an epoxy table using old PCB's, probably a good idea first to remove the lithium batteries from them, because they are going to eventually fail and blow open the epoxy. Same for NiCd and NimH packs, as they also fail with time. If you have a board with Sony SMD electrolytics on it they could also probably be removed, they are notorious for leaking.

[Spongman]

errr. Apple's M1 is definitely based on ARM licensed IP.

[SuperGourmetguy]

Apple M1 is ARM architecture. just souped up. Apple have to pay ARM a licence for every CPU