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

[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