Now here’s a machine I’ve long coveted. My first computer was an Acorn Electron, but I went on to 16-bit Atari machines – the Archie was not a cheap computer at the time. We’re talking a minimum of £800 in 1987 – about £2,200 today.

But the price was warranted. The CPU was entirely of Acorn’s own design – and it was awesome. Whilst an 8MHz Motorola 68000 in the ST or Amiga could perform about 1million instructions per second (MIPS), the Archie’s ARM processors were much faster.

To put the ARM2’s performance in perspective, it was released in 1986 and performed 4 MIPS with a clock speed of 8MHz. The Intel i486DX, state of the art in the PC world in 1989, calculated 8.7 MIPS at 25MHz.

If that 486 were to run at 8MHz, it’d do just 2.8 MIPS. Clock-for-clock, Acorn’s ARM design was pretty impressive.

In fact, Cambridge, UK-based Acorn were clearly on to something. After Acorn folded in 1998, the ARM division was spun-off. Since then, they have been quite successful indeed. Almost every smartphone sold since their invention is powered by a processor based on ARM’s designs. Thank you, Cambridge!

My Archie

I found my new Archimedes A3020 on eBay. Like most Archies out there, it had started life in a school – the seller told me that he’d bought it from his school when they were replacing them with boring old PCs. So, as expected, the machine was covered in pen-marks, scuffs, security-stickers and whatnot.

An Acorn Archimedes A3020 covered in dirt, stickers, etc.
One grubby Archimedes!

But fundamentally it appeared to work. It started up, but the Desktop didn’t load. Instead, it reported some sort of data transfer error. But, given the condition of many old Archimedes, I thought this one could be restored.

The Restoration

Exterior

After the machine arrived we got to work. I’m lucky to have a wife who also enjoys this stuff. So whilst I finished up with some work, she disassembled the machine and set to work cleaning the casing and the keycaps. She used warm water with washing-up liquid and her secret weapon: a magic eraser! These things are great — just abrasive enough to work, without damaging the plastic.

It all cleaned up brilliantly. The casing itself was only slightly yellowed, but the keys and the nameplate were quite severely discoloured. I’m not a fan of chemical-based ‘retrobrighting’, so I’ll wait till next summer and park the machine outside for some sunlight-only whitening. This worked brilliantly with my Atari XEGS.

Interior

I had read a lot of stuff on the excellent stardot.org.uk forums and knew to expect that the internal Li-Ion battery would have crapped its content all over the PCB in the intervening years. My machine did not disappoint.

The battery was in bad shape, as you can see above. Additionally, many of the contacts and solder-points across the board were green with contamination.

I snipped off the old battery by the legs and turned to my bottle of white vinegar. It feels very strange to be pouring the best part of a litre of condiment over a computer, but it’s the right thing to do. Vinegar’s acetic acid neutralises the alkali leakage from the battery. With a bit of gentle encouragement with a toothbrush, all the corrosion was removed after a few minutes.

To then neutralise the vinegar, the board was washed down with distilled water. Finally I gave all of the washed areas a spray of isopropyl alcohol (IPA) to encourage evaporation.

Some hours later, the machine was dry and my wife had put the now-clean keyboard back together. I reconnected the keyboard’s fiddly flexi-cables, hooked up my monitor and turned it on.

Power light? Check! Anything on the screen? Errr. No. Ok – so the CMOS battery-backed memory had probably been corrupted due to a lack of a reliable power source. So, I powered the machine back on, this time holding the DELETE key to reset the CMOS to default.

It worked! The desktop started up and stared hopefully at me. But we’re not done yet.

At least now we know the machine is fundamentally happy. Let’s make it the best A3020 it can be.

The Battery

The RISC OS operating system stores several important bits of data in its battery-backed CMOS memory — stuff like the date/time, the display mode, monitor type, etc. We’ve removed the old battery, but now it needs replacing.

There were a few choices here. The Archie trickle-charges the battery whilst it’s powered on, so the most straightforward option is to replace like-for-like: the old battery cell with a modern equivalent. But I wrote that option off quite quickly – even a new battery will leak at some point in the future, and we really want to protect the PCB from further damage. It’s possible to use a standard non-rechargeable AA battery if a diode and resistor is added to stop the machine from charging it.

I decided on using a rechargeable AA. This way, there would be no harm done by the machine trying to charge it, and the battery could easily be replaced or removed. I soldered a battery-carrier’s leads to the + and – terminals on the PCB. Here’s how it looked:

Rechargeable AA wired to the old battery terminals.

After booting up, I used the !Alarms app to set the date and time and powered-off. A while later, I started it up and success! The clock had kept time. And as a bonus, it seems RISC OS 3.11 is Y2K-compliant!

Floppy Drive

Even if the floppy drive were working 100%, I’d still want to take it apart for a clean. As it happens, the drive wasn’t doing too well. The head motor sounded like a bag of spanners, and the spindle motor wasn’t much better.

Popping the top off and inserting a disk, I could see that the disk wasn’t sitting properly on the spindle. On closer inspection, and by manually turning the spindle, I saw this…

Well, that’d explain it.

The spring from a floppy disk door had fallen into the spindle. Took a bit of effort to extract, but it came out without doing any further harm.

After giving the drive heads a swab with IPA, I cleaned up the ‘worm’ gear that moves the head assembly to get rid of the dried, dirty grease. A dab of silicone grease got the head moving nicely.

Mass Storage

One of the reasons I wanted an A3020 is that they feature an on-board IDE controller. I miss out on joystick ports, present on the A3010, but almost every game has support for multiple joystick setups, including those which connect via the parallel port. So I wanted to add a hard drive

This machine came with a Conner 2.5″ drive, but it was quite thoroughly dead. Instead of replacing it with another spinning-disk, I thought I’d get an industrial-style Disk-on-Module device. These are basically small boards containing SSD-style storage and an IDE interface.

Initially, I bought one of these. Sure, it’d be too tall and foul the top shielding, but I thought I could put it on the end of the existing 44-way IDE cable and lay it down.

The first Disk-on-Module I tried…

This worked great when connected straight to the Archie’s IDE connector. But, weirdly, when used with a known-good IDE cable, it let out a weird electrical shrieking noise. Huh. So I returned it and got this instead…

The DOM I ended up using

This is 16GB which means that 15.5GB of it will go unused since RISC OS’s maximum partition size is ~500MB. A bit of a shame, but never mind. Acorn hadn’t formalised a partitioning scheme for their drives as of RISC OS 3.11, but I think with some experimentation I might be able to set up multiple 500MB partitions.

Anyway – here’s the drive installed, with the battery holder also properly fixed in place.

Neat!

One thing I learned through experience: don’t fit the battery holder any lower that shown. The back of the built-in speaker, attached to the top shielding, will occupy the area below.

Oh – and those 4 upright ICs turn out to be a RAM upgrade, so this machine is fitted with the maximum 4MB RAM. Not bad!

I think that’ll do for now – I’ll post again soon, covering the software setup and final result, as well as some thoughts on how nifty RISC OS is!

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