EEVblog #507 - The First ARM Computer - Acorn Archimedes A3000

[EEVblog]

Dave tears down and attempts repair on a 1989 vintage Acorn Archimedes A3000 Computer, using the very first ARM processor, the Acorn RISC ARM v2

Service manual: http://acorn.chriswhy.co.uk/docs/Acorn/Manuals/Acorn_A3000SM.pdf
Reference Manual: http://acorn.chriswhy.co.uk/docs/Acorn/Manuals/Acorn_A3000TRM.pdf
Schematics: http://acorn.chriswhy.co.uk/docs/Acorn/Manuals/Acorn_A3000TRM_drawings.zip

[Zad]

It looks like that battery is the achilles heel of the Archimedes. There is this one going on Ebay UK at the moment, and this is what the battery looks like:



www.ebay.co.uk/itm/Acorn-Archimedes-A3000-/161083181402

Yeah... Definitely heading in the same direction as Dave's.

These come up quite regularly on Ebay, so I'm not really sure it is worth repairing. Other than the battery issue though, it looks pretty well engineered.

[jaycee]

Unfortunately this is very common on computers of this era with battery backed clocks and suchlike. There are plenty of Commodore Amigas which also suffer the same fate, particularly the A500+ and larger A1000/2000/3000/4000 models which had a battery backed RTC.

If caught early enough they can usually be restored. The usual recommendation is to use something alkaline to neutralise the battery acid from doing further damage.

[MrAureliusR]

As I said on YouTube comments, I think this could be a GREAT restore video, or short series of videos. Just get in there and really scrub with Electrolube IPA, then something to stop corrosion... jump broken traces with thin wire and a steady hand, replace all the off-the-shelf components  (which it looks like they basically all are) and bob's your uncle! I think this could seriously be a very popular video that beginners and experienced EE's alike would find incredibly interesting to watch -- in incorporates many of the things you've done tutorials on together in one job, to show how you attack something like this methodically etc etc. I personally find it very satisfying to restore something this far gone than just a simple 'replace a few caps' job...

Anyway, if you're totally uninterested in doing it, there's a good chance fellow YouTuber jpkiwigeek would be interested in repairing it - he basically fixes old broken computers and documents his really incredible collection of vintage stuff. Plus he's a fellow "from down under"-er... 

I suppose, like most of us, you've probably got more going on that's of more interest to the blog though, so maybe this isn't an ideal project...

[EDIT] Someone suggested sanding down the problem areas, to get through the solder mask and to the traces. Then use conductive paint/epoxy or something similar to repair! That's an even better idea than what I was thinking. I mean, this could seriously be a cool way to show how to come up with a novel approach to fix something like this. The sand/conductive paint is just one option. I'm sure there are many other ways!

[c4757p]

I agree. You've got the makings of a very good short series here, Dave.

[Zad]

Way back when this Archimedes beastie was being made, I got myself £1000 worth of Technics hifi for £90 by doing this sort of repair. The tuner had been dropped in the shop and split the PCB in 2 - there was only a small dink in the case to show for it too. Unfortunately for the shop, all the remote control signals for the separates went through the tuner, so it was essentially useless (or so I convinced them). The PCB was only double sided, but the track widths were surprisingly fine and dense. An ideal job for a slightly short-sighted teenager.

A few metres of 30AWG Kynar, a fibreglass pencil and a couple of hours had it sorted. Those fibreglass pencils are excellent for this sort of repair work.

[gslug]

I still have an Archimedes 310, though I haven't used it in years. That has a couple of AA batteries mounted off-board and connected to a header on the PCB. I didn't realise that the A3000 used a coin cell.

The leakage problem seems to be common in a lot of 1980s electronics. I have a few synthesisers which use battery backed RAM to store the patches. So far I have been lucky, but whenever I get a "new" toy, the battery is one of the first things I check.

BTW, this is my first post here so I guess I should say Hello!

[Tothwolf]

That board really doesn't look too bad compared to some. The trick is to neutralize the alkaline solution that's corroding the metal parts and traces. I've used this cleanup technique probably 100s of times and it should give you pretty good results: http://www.classiccmp.org/pipermail/cctech/2012-October/098565.html
http://www.classiccmp.org/pipermail/cctech/2012-October/thread.html#98562

I don't really recommend sanding off the solder mask unless you need to repair a trace. Once you neutralize the alkaline mess, the small amount of tarnish/corrosion under the solder mask won't really cause any further trouble.

On the upside, the ROM socket damage also gives you a good excuse to replace the cheap leaf contact sockets with higher reliability machined pin sockets. You may find that you need to pre-tin the solder pads with fresh solder and a liquid flux before installing the new sockets. (I generally just desolder, re-tin, and then desolder again before fitting the new components.) Some battery electrolyte solutions can do some really weird stuff to these solder connections and make resoldering them quite tricky if you don't remove the old contaminated solder.

[orin]

If caught early enough they can usually be restored. The usual recommendation is to use something alkaline to neutralise the battery acid from doing further damage.

It's a NiCd - the electrolyte is alkaline.   If you wanted to neutralize it, you'd have to use an acid.

There are some that say that neutralizing with an acid runs the risk of insoluble precipitates that you'll never get ride of, so it's best just using plain water.

I'd give it a good old rub-a-dub with plain water, followed with distilled or de-ionized water, followed with iso-propyl alcohol to help get rid of all the water.  Bake at 150 deg F for a few hours to dry it out.  Pick your own temperature - 150 shouldn't do anything any harm.

I have a Fluke 731B in need of this treatment.  Fortunately, someone caught it before it got anywhere near as bad as Dave's Acorn.  I keep putting it off since the unit is working.  Whoever cleaned it in the past didn't get all the contamination off the board.  You can put a test lead on a trace and run another alongside on the board and read about 3M ohms.

The problem is on the power supply board which is a low impedance point, so it shouldn't be much of a problem (and it isn't as far as the output voltage is concerned), but the leakage is to the guard terminal - it makes the guard terminal useless.

In my case, I'll have to unsolder the bridge rectifier as the contamination clearly goes under it.  Between the contamination and desoldering, the plated through holes will likely be destroyed.  I have a pcb repair kit with eyelets/funnelets* waiting in the wings... I already have repairs to do where the battery connector header pin was broken off.  No solder mask, so the battery wire is soldered directly to the trace at the moment.

Orin.

*that does seem to be the usual spelling, though I've seen 'funnelette' too.

[orin]

Shame about the Acorn being in such poor shape.

In the early to mid eighties, in a former life, I went to Acorn in Cambridge to look at putting Unix on the original ARM chip.  Nothing ever came of it* to my knowledge - the ARM chip at the time wasn't that suited to Unix - they had separated their supervisor/user modes too well.  What they had done was produce an amazing CPU chip for its time given their resources.  Personally, I'd probably have preferred the NatSemi 16032 for ease of programming, but where did that go?

Decades passed and I didn't use the ARM architecture to my knowledge before the Luminary Micro Stellaris chips in the last decade.  The RISC premise worked and still works.

I went onto the Intel 286 (UGH!) and 386 (slightly less UGH!).  The baggage the Intel chips carry to still support the segmented architecture is amazing.  (Though occasionally it was useful when the behind the scenes segment limits weren't reset when the chip went back to real mode.  You could set the limits to 4GB in protected mode, return to real mode and access all memory using 32bit instructions!  Remember himem.sys?  It used that trick.)

Orin.

*at that time of course

[Tothwolf]

If caught early enough they can usually be restored. The usual recommendation is to use something alkaline to neutralise the battery acid from doing further damage.

You mean a mild acid (such as white vinegar).

Alkaline, NiCd, NiMH, etc have an alkaline electrolyte, not acid. You'd use a mild acid like white vinegar to neutralize it, followed by a water rise and something like baking soda to to neutralize any residual vinegar, followed by another clear water rinse. Alkaline, NiCd, NiMH, etc tend to be pretty easy to clean up after, but carbon zinc "heavy duty" batteries often make a huge mess and stain everything (even plastics) bright orange.

[true]

Ctrl in this position is a relic of the IBM XT, and really it makes more sense as it is on the Acorn than the position we have it in now...

[mikeselectricstuff]

Acorn had some "history" with batteries - on the BBC Master, the last of the 6502 range, they used an AA lithium cell, and had a couple of "being on fire" incidents in schools, I think due to reverse-charging through diode leakage.
They did an ugly field replacement using a pack of 3 alkaline AAs on a metal plate which screwed into a rarely used peripheral slot, and subsequently became very cautious about batteries, tending to use alkalines or nicads in future models.
 

[G7PSK]

I have found that the best thing for removing corrosion from battery electrolytes whether acid or alkaline in nature is soap and water, seem to neutralise both as well as dissolving the residue and when you have that much spillage it really doesn't matter immersing the whole board in water just rinse with fresh water and then alcohol and place in a warm oven to dry, about 50 or 60 deg C. for a while or sit on top of the hot water cylinder overnight. 

[Psi]

Here's how i'd approach the repair.

- Unsolder every component within the area and keep note of values and locations.
- Remove all the soldermask from the area with some sandpaper. This will remove any loose/corroded tracks as well, all that will remain is the intact copper which makes it obvious where the breaks are.
- Tin all exposed copper with solder
- Solder bare wire along and over the top of any broken tracks
- Spray with pcb lacquer
- Reinstall components
- Test

[MrAureliusR]

Hey Dave -- on second thought if you don't feel like repairing it feel free to send it to me and I'll make a video series out of it  

Typed using Hacker's Keyboard for Android

[rolycat]

In the early to mid eighties, in a former life, I went to Acorn in Cambridge to look at putting Unix on the original ARM chip.  Nothing ever came of it* to my knowledge - the ARM chip at the time wasn't that suited to Unix - they had separated their supervisor/user modes too well.

Acorn did produce an ARM2-based Unix machine in the eighties - the R140, which cost £3,500 when it was released in September 1988. The machine was adapted from the A440. The OS was called RISC iX and was based on BSD4.3 Unix.

As far as I know it was the first commercially available ARM Unix computer.

[LaurenceW]

It's a question of return on investment, isn't it? No doubt if somebody's LIFE depended on it (and like, this was the last A3000 on the PLANET), then Dave could repair it, yes. But given the state it's in, this is a big ask, just for the "fun" of it. Especially when "other Acorns are available."

I'd share Dave's reluctance to invest time on this one. Part of being an EE is knowing when to bail out.

[orin]

In the early to mid eighties, in a former life, I went to Acorn in Cambridge to look at putting Unix on the original ARM chip.  Nothing ever came of it* to my knowledge - the ARM chip at the time wasn't that suited to Unix - they had separated their supervisor/user modes too well.

Acorn did produce an ARM2-based Unix machine in the eighties - the R140, which cost £3,500 when it was released in September 1988. The machine was adapted from the A440. The OS was called RISC iX and was based on BSD4.3 Unix.

As far as I know it was the first commercially available ARM Unix computer.

That was a few years later then.  I wonder who did it.  Did they do it themselves or was it Logica/SCO?

[AndyC_772]

Looks like they did quite a few Unix boxes, not that anyone really ever bought them.

http://acorn.chriswhy.co.uk/RISCiXComputers.html#R140

The original Archimedes ran an OS called "Arthur", later updated to RISC OS version 2. The RISC OS 3 ROMs that Dave identified as probably being newer than the rest of the unit were indeed an upgrade.

I still have a set of the original RISC OS 2 ROMs, manufactured by Toshiba, sitting in a drawer from when I upgraded my own A3000 back in the early '90s!

It was a nice machine - remarkably fast and capable for its day - but always suffered from a lack of memory, and its early performance advantage over the competition was never really maintained. The ARM2 processor could, on many machines, be removed and upgraded to an ARM3 processor on a carrier board, which added a cache and a speed boost to 25 or 33 MHz. RAM upgrades were costly, and the genuine Acorn 2MB upgrade (1MB on the main board + 1MB on the expansion board) on Dave's machine was quite uncommon as there were plenty of cheaper, functionally identical 3rd party alternatives.

After a few years I upgraded from the A3000 to the newer A5000, which had the ARM3 processor, a built in IDE controller and room inside the case for a hard disc - an expensive peripheral which was only just becoming commonplace. It also had a faster video clock, which allowed it to display higher resolutions and was really worthwhile.

The GUI was attractive and usable, and there's never been an easier machine to start programming since. At any time, press F12 and the GUI scrolls up and you have a command line. Type 'BASIC' and you get BBC BASIC version V, which includes a full ARM assembler. C was available as a commercial package from Acorn and I regret not learning it back then - but there was no need, BBC BASIC was so fast and capable.

Despite the fact that RISC OS used co-operative rather than pre-emptive multi-tasking, it was a lovely machine to use, and way ahead of the competition in many ways. Unfortunately it never caught on commercially in the way the PC did. I still miss my A5000.

[nathanpc]

Dave really has the worst luck ever in terms of getting products to make a repair video, they are either working or seriously damaged like this one, but I think this would make for a great "extreme" repair video, but it would take a lot of time and patience to repair it like he described in the video.

[c4757p]

I'd share Dave's reluctance to invest time on this one. Part of being an EE is knowing when to bail out.

True. Still, if he were willing to put in the work (I know he's very busy, though), I think this could be a great opportunity for a very popular and informative video series. There are a lot of people interested in this kind of repair work.

[jahonen]

This video reminded me that I really should remove the NiCd battery from Amiga 4000 that I still have lying around. Fortunately I already had replaced the battery once. There was no leakage from the battery, but I still removed it as one can never know if the battery decides to leak. I intended to remove the charging resistor and run the RTC backup from lithium battery but didn't bother with that. Ended just removing the NiCd battery.

Regards,
Janne

[Spunky]

I used to fix these back in the 90s, and I too would bail out upon seeing that mess. The problem for me was knowing I'd never get paid for my time if it took more than 2 hours.

Great to see one of these old micros again though. I smiled when I saw Dave unscrewing the disk drive...and sure enough it fell out. LOL

[Stonent]

I haven't watched the video yet because I'm at work, but was there ever an NTSC version of this released?

[TheWelly888]

I loved the A5000 and RISC PC that my Dad had back in the early 1990s which was why I clicked on the Thumbs up even before the video started! They were light years ahead of PCs at the time - I remember demonstrating the dramatic difference in the speed of a graphic program written in Basic between the 386SX PC and a RISC PC even though they both used exactly the same 25MHz processor clock speed!

Great pity about the battery corrosion - it's a no-hoper for Dave to repair! 

Thankfully 95% of mobile phones uses ARM otherwise we would all be carrying portable handwarmers!

[dr.diesel]

http://acorn.chriswhy.co.uk/RISCiXComputers.html#R140

This link cost me an hour or so, loved every minute, thanks!

[mikeselectricstuff]

Incidentally there is a version of RISC OS for the Raspberry  Pi - I've been meaning to try it some time. Would be fun to see how fast those old BBC micro graphics demos run!

[synapsis]

I know on automotive batteries they have sleeves you can put over the terminals to help reduce corrosion issues. Are there similar types of pads that can be used in old electronics to prevent the issue in Dave's Acorn?

All of my old computers are early Commodores (VIC-20 power!), but I've seen the corrosion issue in industrial PLCs.

[Miba]

Did I heard right?

Dave said "the battery is KAPUTT".

LOL!

[rolycat]

Did I heard right?

Dave said "the battery is KAPUTT".

LOL!

Not exactly; I don't think Dave was suddenly dropping into German, if that's why you are LOLing.

He said "The battery has gone kaput".

Kaput is a fine English word commonly used in (at least) Oz, the US and the UK.

It was appropriated about a hundred years ago from the German "kaputt", which was in turn derived from the French expression "être capot". Capot was originally a Provencal word derived from the archaic Spanish term "capuzar",  meaning to capsize.

The word also turns up in lots of other languages, including Russian and Yiddish.

It's all very international, which seems appropriate for this forum.

[rj2k000]

I use "Safewash 2000" from RS Components to fix these messy problems. Pour some on the PCB then rub in with a large paint brush for a few minutes, then rinse the PCB under a tap. All the metal will look shiny new, and all oil and flux removed.

[jancumps]

The word also turns up in lots of other languages, including Russian and Yiddish.

It's all very international, which seems appropriate for this forum.

yes, it show up in our language as slang for a prophylactic

[long_eggs]

hey
ive watched your blog vids for quite a while, dave. signed up to post this.

i'd love to see a restore of this because this kinda problem isnt easy and its quite a common thing really (fucked up boards and components). restoring a corroded board is something i have no idea of how to tackle and in the past ive had the same feelings as shown in your blog video and given up. id like to see you persevere however - id love to see how you fix this ball-ache.

please fix this thing and make a video!

cheers

[jancumps]

There is a lenghty video of the repair of an infected Amiga 500+.

Amiga 500+ corroded motherboard repair

It does not show how to get rid of the crud, because that was done by someone before the blogger received the pc. Not the same damage, but you get an idea of the work related to fixing it.

[MrAureliusR]

I know on automotive batteries they have sleeves you can put over the terminals to help reduce corrosion issues. Are there similar types of pads that can be used in old electronics to prevent the issue in Dave's Acorn?

All of my old computers are early Commodores (VIC-20 power!), but I've seen the corrosion issue in industrial PLCs.

Hey I just got my very first vintage computer a while back for free - a VIC-20 in the original box! I've got nothing else for it yet. I've been thinking about building a copy of SD2IEC using an ATmega644 and their open source schematic. I've already got too much on the go so the VIC hasn't gotten all the attention it deserves but I've opened it up many times and I'm starting to understand it. Is there anything I can do to help protect it? I was thinking of pulling the ROMs and dumping them just in case but I don't know if I could even find a replacement chip.

I've been keeping my eyes open for free Acorns on my local kijiji/Craigslist. Hope I find one! The VIC was total freak luck.

Typed using Hacker's Keyboard for Android

[Crazy Ape]

I know on automotive batteries they have sleeves you can put over the terminals to help reduce corrosion issues. Are there similar types of pads that can be used in old electronics to prevent the issue in Dave's Acorn?

All of my old computers are early Commodores (VIC-20 power!), but I've seen the corrosion issue in industrial PLCs.

Hey I just got my very first vintage computer a while back for free - a VIC-20 in the original box! I've got nothing else for it yet. I've been thinking about building a copy of SD2IEC using an ATmega644 and their open source schematic. I've already got too much on the go so the VIC hasn't gotten all the attention it deserves but I've opened it up many times and I'm starting to understand it. Is there anything I can do to help protect it? I was thinking of pulling the ROMs and dumping them just in case but I don't know if I could even find a replacement chip.

I've been keeping my eyes open for free Acorns on my local kijiji/Craigslist. Hope I find one! The VIC was total freak luck.

Typed using Hacker's Keyboard for Android

There is no battery in the VIC-20 (my first computer, still in a box somewhere as well) so the circuitry safe from damage such as in Dave's video of the A3000.
The original ROM's are mask roms so they should also be fine. Various versions of the VIC-20 (and most other machines from that time period) roms have already been dumped and are available for download at various places on the internet (the are used by emulators).

Check out some simple 6502 based designs/schematics on the net, then look at the VIC, you'll find things are very similar and you'll gain knowledge of the architecture in general.

[MrAureliusR]

Yeah I've been playing with my Z80 a lot so I understand it better. I really want to find a computer that uses a Z80! I know the TRS-80 did and I want to find one. I don't know why but I absolutely am in love with the Z80. Its just such an awesome chip.

Do you know which chips are the mask ROM in the VIC? I couldn't figure out which was which using process of elimination. Are they the socketed ones in the upper left? Or the one near the processor? For some reason I've had a hard time finding this info online.

Typed using Hacker's Keyboard for Android

[MasterOfNone]

That video reminded me of the RISC vs CISC CPU wars of the 80s and 90s.  I’m still not sure who won that one since the ARM seem the have a hold of the Mobile & Tablet Markets, whilst the Intel dominate the desktop and server markets. Apple initially backed the RISC CPU’s by using PowerPCs (after moving from the Motorola 68000 series CPU’s), but they later moved to Intel CPU’s because the PowerPC’s couldn’t seem to keep pace with the development of the Intel and clones.
The Acorn Archimedes was the first Commercially available RISC based computer that I knew of, but there may have been others.

Yeah I've been playing with my Z80 a lot so I understand it better. I really want to find a computer that uses a Z80! I know the TRS-80 did and I want to find one. I don't know why but I absolutely am in love with the Z80. Its just such an awesome chip.

In the early 80s the most popular home computer was the ZX Spectrum, and it used a Z80 CPU. There are loads on the UK E-Bay (of various shapes and sizes). However these computers were aimed only at the home market unlike the TRS 80.

[Crazy Ape]

Yeah I've been playing with my Z80 a lot so I understand it better. I really want to find a computer that uses a Z80! I know the TRS-80 did and I want to find one. I don't know why but I absolutely am in love with the Z80. Its just such an awesome chip.

Do you know which chips are the mask ROM in the VIC? I couldn't figure out which was which using process of elimination. Are they the socketed ones in the upper left? Or the one near the processor? For some reason I've had a hard time finding this info online.

Typed using Hacker's Keyboard for Android

Z80:
The Sinclair ZX80 and ZX81 machines are very simplest Z80 based designs, have been copied many times, schematics posted to the net etc.
Lot's of related DIY stuff.
Too many to pic any specific ones - use Google etc.
https://www.google.com.au/search?q=zx80+schematic&source=lnms&tbm=isch&sa=X&ei=xbAQUvyhL-iyiQeRg4CoCQ&sqi=2&ved=0CAcQ_AUoAQ&biw=1920&bih=889
https://www.google.com.au/search?q=DIY+z80&hl=en&source=lnms&tbm=isch&sa=X&ei=z7AQUofsFu2kigeV64HACw&ved=0CAcQ_AUoAQ&biw=1920&bih=889


VIC-20:
The rom locations changed a bit across the different boards, but the basic and kernal roms are located closest to the CPU.
Lots of info on the net but these links will get you started.

These deal with replacing ROM:
http://blog.tynemouthsoftware.co.uk/2013/02/commodore-vic20-repair.html
http://mutantcaterpillar.wordpress.com/2012/02/23/help-ive-forgotten-how-to-boot/

Add some ram:
http://www.jammarcade.net/commodore-vic20-memory-upgrade/

The other type of VIC-20 board you might find:
http://www.the-liberator.net/site-files/retro-games/hardware/Commodore-VIC-20/Commodore-Vic-20-Germany/Commodore-Vic-20-008-Motherboard.JPG

Lot's of info:
http://sleepingelephant.com/denial/wiki/index.php?title=VIC-20

VIC-20 Schematics:
http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/vic20/

[alm]

That video reminded me of the RISC vs CISC CPU wars of the 80s and 90s.  I’m still not sure who won that one since the ARM seem the have a hold of the Mobile & Tablet Markets, whilst the Intel dominate the desktop and server markets. Apple initially backed the RISC CPU’s by using PowerPCs (after moving from the Motorola 68000 series CPU’s), but they later moved to Intel CPU’s because the PowerPC’s couldn’t seem to keep pace with the development of the Intel and clones.

Modern x86 CPUs aren't CISC. They're essentially RISC processors with a CISC front-end. Since the number of transistors involved in the ALU/FPU/cache is constantly increasing, the incremental cost of adding a more complex instruction decoder has become fairly small.

[MasterOfNone]

Modern x86 CPUs aren't CISC. They're essentially RISC processors with a CISC front-end. Since the number of transistors involved in the ALU/FPU/cache is constantly increasing, the incremental cost of adding a more complex instruction decoder has become fairly small.

Great point I really didn’t know that, thanks 

[Stonent]

There is a lenghty video of the repair of an infected Amiga 500+.

Amiga 500+ corroded motherboard repair

It does not show how to get rid of the crud, because that was done by someone before the blogger received the pc. Not the same damage, but you get an idea of the work related to fixing it.

I once repaired a water damaged Sun Sparcstation 5 keyboard with a PCB trace pen. It had layers of plastic which made up the membrane part of the keyboard, I just drew over all of them with the pen and it worked great for several years afterwards.

[Hypernova]

That video reminded me of the RISC vs CISC CPU wars of the 80s and 90s.  I’m still not sure who won that one since the ARM seem the have a hold of the Mobile & Tablet Markets, whilst the Intel dominate the desktop and server markets. Apple initially backed the RISC CPU’s by using PowerPCs (after moving from the Motorola 68000 series CPU’s), but they later moved to Intel CPU’s because the PowerPC’s couldn’t seem to keep pace with the development of the Intel and clones.

Modern x86 CPUs aren't CISC. They're essentially RISC processors with a CISC front-end. Since the number of transistors involved in the ALU/FPU/cache is constantly increasing, the incremental cost of adding a more complex instruction decoder has become fairly small.

Things have pretty much come full circle with many RISCs adding back what is effectively CISC multimedia/cryptographic/DSP instructions. It's a bit like Pentium 4, the idea of doing only little things but do them quickly didn't really work out as envisioned.

[notsob]

Don't worry Apple are not missing out

The company was founded as Advanced RISC Machines, ARM, a joint venture between Acorn Computers, Apple Computer (now Apple Inc.) and VLSI Technology

[davec]

It looks like that battery is the achilles heel of the Archimedes. There is this one going on Ebay UK at the moment, and this is what the battery looks like:



Yeah... Definitely heading in the same direction as Dave's.

These come up quite regularly on Ebay, so I'm not really sure it is worth repairing. Other than the battery issue though, it looks pretty well engineered.

Actually, that one wasn't as bad as the one Dave got.

After a cleanup with vinegar solution and replacing a capacitor, a crystal, one track and adding a CR2032 and a diode, the one shown above is back up and running fine.



I had been watching this and a few others, I was specifically after a dead one as I was planning to 'upgrade' it with a Raspberry Pi, also running RISC OS on an ARM, like the original.

I suppose it's my own fault for fixing it, can't help it, it's force of habit.

Full details on my blog: http://blog.tynemouthsoftware.co.uk/2013/08/acorn-archimedes-a3000-repair.html.

Thanks,

Dave

[station240]

Its not just the roms, IC6 (PCF 8583P) is the I2C connected eeprom/RTC device. Without that working as well the machine either won't boot or fail to keep its settings.

The 1772 IC is the floppy disc controller, oh and the machine originally came with RISC OS 2, which users/technicians upgraded by replacing all 4 chips.

The econet board is common to many of Acorns machines, and was part of a complete computer network with up to 254 machines and dedicated file and print servers. See http://acorn.chriswhy.co.uk/Network/Econet.html
I've actually got an econet network myself, it takes up a lot of room.

[vk3pb]

HI all, Dave

I was just watching the video and was curious to now what became of Dave's BBC Micro. Did he restore it? Did he junk it?

My recommendation is to strip out the internal board and replace it with a 512 mb Raspberry Pi>

I'd be keen also to see how Dave interfaces the Pi to the keyboard.

cheers

Peter VK3PB

[MrAureliusR]

Doubtful, as Dave isn't into the Pi at all. He just got one in the mailbag and said exactly that. I doubt we'll ever see it in a video.

But yeah, I'd love to see that Acorn restored. I wish he'd sell it to me so I could do the work on it and get it up and running.

[geek]

I don't think the problem is with corroded roms only. It should output some video signal even without ram, rom and cpu. So, first step would be to make it to generate video, and only then to fix the roms

[mikeselectricstuff]

I don't think the problem is with corroded roms only. It should output some video signal even without ram, rom and cpu. So, first step would be to make it to generate video, and only then to fix the roms

No - it needs the video & memory controllers to be set up by the firmware to produce a video signal

[EEVblog]

I was just watching the video and was curious to now what became of Dave's BBC Micro. Did he restore it? Did he junk it?

Still got it, but it's beyond economical repair.

My recommendation is to strip out the internal board and replace it with a 512 mb Raspberry Pi>

Could be done if I could find the time...

[muffenme]

Bill a daughter board to replace the area that has been effected by the battery.   This looks to be a simple job from what I seen you do.  I like to see some image of the effected area.  Even today motherboard manufacturer has this ideal of putting a battery on the motherboard with protecting the board.

[Fungus]

I actually had one of those things back in the 80's...