Whilst I am interested in old tech and computers of all types, I’ve come to realise lately that my favourite brand from the 80s is Amstrad. Not perhaps everyone’s choice, but I was really into Amstrad at the time (owning a PCW 9512 which I would still love to replace). I also used various Amstrad PCs which were something of a phenomenon at the time for their low price. Although I never actually owned any other Amstrad products I followed them eagerly and well remember looking at them in Dixons etc on the High Street. They had a reputation for making packaging up previously expensive or complicated things (eg hifis) and making them cheap and easy to use. Whilst at the time people grumbled about the quality, looking back it now I think that their stuff was actually pretty well designed and well made, and the savings were often made by clever design decisions.

One of the more interesting Amstrad products of this era is the company’s first take on a portable computer – the Amstrad PPC. Laptop / notebook / portable computers in the mid to late 1980s were expensive and exotic things costing thousands of pounds, and the idea of portable PC computing was completely out of reach for most. The PPC followed the usual Amstrad philosophy and delivered a portable computer at substantially reduced price.

I’ve recently picked one of these up, which is the top of the range PPC640D. The design is really interesting, with a small folding LCD screen, and then a full sized desktop style keyboard which folds over the whole of the rest of the machine. There are two 720k 3.5″ floppy drives on the right hand side, and an internal 2400 baud modem – which was a really impressive addition at the time. The overall package feels surprisingly solid and sturdy.

I bought this without any idea if it worked or not and there have been a few issues. The first concerning getting the machine to start up properly. It came without a power supply, but fortunately (and unlike many portable computers) runs off a standard 12V power supply with a barrel connector (centre positive). You do need a fairly beefy one because of the current requirements. You can also – uniquely I think for a portable PC – run it off standard ‘C’ batteries (10 of them!) although I can’t imagine you’d get much running time.

The power switch (just to the right of the screen) is also a bit odd in that it switches between two ‘on’ states – either ‘battery on’ or ‘external on’. With an external power supply connected I was pleased to see the lights come on and ‘Please Wait’ on the screen. However, after a few seconds there were three beeps and just a flashing cursor. The disk drives ran for a few seconds, but beyond that no response.

There isn’t a huge amount out there written about these machines but I did find this reference to a similar issue. It’s all about a small bank of DIP switches which are hidden away on the side of the machine. The relatively basic nature of the hardware means that the display is not auto-detected in any way and the switches are used to set the display options. If you get it wrong then there is nothing on the screen. There is a useful guide to the DIP switches here. When I got it, all the switches were down ie on, which led to a fault condition in which the internal display was set to a CGA (ie colour) mode but the screen type was set to MDA (ie monochrome). The solution was to either set the screen mode to MDA (switch 2 off) or the screen type to CGA (switch 4 off for 40 columns or switch 5 off for 80 columns). I opted for the latter, and the switches now look like this:

I can’t really work out why they were ever set to all on, except perhaps someone well meaning thinking it looked neater!

The second issue was about the casing itself. Although it felt sturdy enough I could hear bits of plastic rattling around inside. More significantly, there was clearly something wrong with screen hinge, and although it did work it was not very stable and you could see one of the pins on one side was loose.

Getting inside was pretty easy – 6 large screws on the base, with two of them inside the battery compartment. When I got it open I was surprised to find there was a lot more damage than I expected, with several of the screw posts broken off, and various other bits of trim rattling around:

Fortunately, the breaks were pretty clean and it was easy to see where the broken pieces went back, so it was just a question of mixing up plenty of epoxy resin and sticking the various bits back where they came from.

Getting screen out was a bit more tricky, and requires removing one of the motherboards, the modem and several connectors:

This picture shows where you need to get to. The board at the top of the picture usually sits on top of the other one, with a large connector block as well as a few power cables. The modem is a separate board on the right hand side (with the grey box).

Of particular note are the three ribbon cables top left, two of which are the keyboard and the other the screen. These push in to connectors on the top board:

First of all there are a few screws (indicated by arrows) to remove. There are so many different connectors it is tricky to get everything out, but the simplest thing to do is unplug the blue and white connector blocks first, then ease the board upwards and then it should be possible to flip it over so that you reach the ribbon cables, which just pull out. You do need to very careful with these as they are rather fragile.

Having done this, the screen can then be removed. It’s held in place by plastic pegs which locate in holes on the chassis, and with a bit of careful wiggling around it will come out. The problem was immediately apparent:

One of the plastic pegs had snapped off. This proved tricky to resolve – the peg is designed to move slightly in and out and is moulded to be flexible, but trying to fix it in place spoils this. I didn’t take enough pictures, but in the end I glued a thin piece of plastic inside the screen behind the peg, and then glued the peg to that to give it more support. Others have suggested drilling a small hole in the peg and using a metal pin for support, or else even more drastic solutions.

My approach didn’t quite work out as planned. Not all of the glue stuck properly, and the peg is still a bit floppy. However, it’s definitely better than it was before and the screen stays in place. I could have another go at it but it’s good enough for what I want it to do.

Having put everything back together again, it only remains to get it started. The machine did come with a pile of disks including one of the original Amstrad ones. This didn’t work, but with the help of a Greaseweazle (another article for another day) I was able to write a new image out to it:

Success! It boots up nicely to DOS 3.3. There’s quite a lot of interesting things to explore with this now, including testing the internal modem. However for now I’m happy to have it restored to working order again, and I’m debating taking it out somewhere and trying to do some real work on it. Would draw a striking contrast with the usual selection of Macbooks seen in my local coffee shop!

One of the first things I bought when I came back to retro computing was a Commodore 64. I’d never had one of these before, having been firmly in the Spectrum camp when I was growing up. For some reason I’d never really had the curiosity to explore this before but I decided the time was right and bought a decent bundle off eBay, which came with a handsome bundle of games which were fun to explore. It was also interesting experiencing tape loading complete with music which didn’t happen on a Spectrum.

One thing I quickly discovered on reading around was that the original power supply was something of an accident waiting to happen, with some quite sensational articles with dire warnings of impending doom. Unlike a lot of early computers it is a reasonably complex power supply with a 9V AC and a 5V DC rail which feeds a DIN plug, and so it’s not absolutely straightforward to replace.

The original design of these is extremely odd (it seems to me) in that the they are fairly simple devices with a transformer and voltage regulator, but then the whole lot is encased in epoxy resin making it a heavy and completely solid block. I really can’t imagine why they did this, other than perhaps to make absolutely sure that no-one actually tried to service it. I’ve not seen any other computer manufacturer of the day do anything like this. The problem referred to above is due to a breakdown of the DC voltage regulator, which is buried in the epoxy resulting in a significant over-voltage and generally a destruction of the C64 itself. The epoxy is also poor at radiating heat which I’m sure doesn’t help the situation

There are various opinions out there on what to do about this – most people recommend avoiding the stock PSU, although I tested the voltages on mine and it was fine. There are quite a number of third party units which are very nice, but rather expensive for what they are:

After a lot of debate, I took the view that the only issue with the stock PSU was the regulator, and after finding a few other examples of people who had modified it I thought I would do the same. There are various different types of these, but mine is the so-called ‘wedge’. Others are just big rectangular bricks, but all of them have the same epoxy construction.

The first thing to do is get into it – easier said than done. The plastic base is glued on, and part of it is buried in the epoxy itself. So it does take a lot of pushing and prying (and some cutting with a sharp knife) but eventually it comes off. All you can see is what is below – most of the wiring is buried in the epoxy but there are taps straight of the transformer for the AC supply, and then via a regulator (circled in red) for the 5V DC.

So there are two jobs to do – the first is disconnect the existing regulator, and the second is to provide some kind of modern alternative. The first is a fairly simple matter of desoldering the pads and cutting off and removing the regulator legs. You could probably manage without this but I really wanted to make sure there was no danger of issues down the line.

There are various modules out there for regulating / rectifying voltages (Buck converters etc) but the guide I linked to above suggested using a ‘UBEC’ (Universal Battery Eliminator Circuit). This is something used in remote control vehicles for getting high voltage battery pack outputs converted down into the lower voltages needed. So it’s ideal for my needs, which is to convert the 9V AC from the transformed into the 5V that I need.

These are cheap and easy to find on eBay and all the other usual sources:

These are not particularly sophisticated devices, and there is apparently a fair bit of electrical noise on the output but these older computers are not sensitive enough to be troubled by it. You do have to configure the UBEC with jumpers to get the 5V you need. It’s also small enough to fit neatly inside. You need to connect the input to the UBEC from the main smoothing capacitor, and the output to the output pin from the voltage regulator (the right hand one on the the photo below). The negative output can simply be left unconnected.

If you’ve done it right, then you should be able to measure about 5V coming out and off to the C64. It’s then just a matter of fitting everything back together again.

Overall it’s a fairly easy job and I am now confident that I can use the power supply without issue. A nice spinoff is that it runs much cooler and still looks authentic. It’s been running happily for long periods with no problems at all.

Since last posting things have moved on considerably and I have picked up quite a lot of new and interesting items. I’m going to go into these in more detail as we go but I’m going to start with a bit of curiosity.

One of my recent pickups has been a nice Atari 1040STE outfit. I’ve had a longstanding ‘relationship’ with the ST. It was the first 16 bit machine that I became aware of back in the 80s, and although later on I became more interested in the Amiga I never actually had either of them although I did borrow an ST for a time.

Looking back on it now, whilst I know the Amiga is superior technically I really like the industrial design of the ST which is I think is much sleeker and more interesting than the Amiga and especially the peripherals (mouse, monitors etc). So when it came to revisiting it all, I started with the ST again.

I didn’t mind too much which variant I got but after a bit of looking around I found a boxed 1040STE with various bits including several boxes of disks and a ‘Powerplay Cruiser‘ joystick. The STE is an enhanced (hence ‘E’) version of the original ST with a blitter, stereo sound and a few other refinements although from what I gather very few games supported this. It’s always a gamble when you buy tech like this but I was pleased to find that it was in good cosmetic condition and (surprisingly perhaps) in full working order including the disk drive.

Whilst it does have a TV modulator (and the picture was surprisingly good on my Trinitron TV) I wanted to connect it to a proper monitor, and one of my other pickups in recent times was a Philips CM8833-II monitor. So the first job was to get a suitable cable.

There are plenty of ebay traders selling ready-made cables although these are usually SCART rather than anything else, and I do quite like the ritual of making cables up. One sticking point is that for some reason the ST uses a lot of very odd connectors (including the notorious 19-way D type connector). The monitor is no exception and uses a very strange 13-way DIN connector with the pins arranged in almost a square pattern:

About the only other thing I know of which uses this is the equally obscure power connector on the Yamaha CX5-M MSX computer. I have an interest in these too and will talk about these in future, but a word of warning if you like these is never buy a CX5-M without a power supply because it’s quite difficult to make a replacement because of the connector and the need for various positive and negative voltages.

So if I wanted to make my own cable I’d need to source the connector. Fortunately they are not that hard to find on ebay these days, but on looking around I found something even better:

This is a ‘new old stock’ (‘NOS’) Atari ST monitor cable which was sold by CPC back in the 1980s. CPC is still around (as part of the mighty Farnell empire) and these days are a general electronics retailer (pretty good too, I’ve had a fair bit of stuff from them). However back in those days they specialised in spare parts for also sorts of consumer electronics, and I remember the catalogue which had complete parts lists for Sinclair, Amstrad and other computers. They obviously handled others too, and this cable was specifically sold as a ‘DIY’ with the 13 pin DIN on one end and pre-prepared stripped wires at the other end.

The pinout for the ST is widely available but here it is for convenience:

There’s actually quite a lot of interesting stuff on here which you don’t always find, including a pin 8 which is used for SCART switching, pin 01 which carries audio (but only in mono) and a choice of composite, mono or RGB video signals. There is also (oddly) an audio in on pin 5 but I’m not quite sure what you’d use that for.

The Philips CM8833 range have quite a choice of different connectors depending on the exact variant but the one I have uses a 9 pin D connector:

V & H on the above refers to vertical and horizontal sync. Although the monitor does have an internal amplifier and speakers, you can’t feed it from this connector but you have to use separate phono inputs instead. This is a pain and so you need to run a separate set of wires either from the back of the computer (which has L & R phono outputs) or you could possibly run one out of the D connector but this would be awkward.

The only thing left to do is work out which wire goes where. You would hope the colour coding would make some kind of sense but you can’t take it for granted. So in case any one else happens to find one of these cables (there do seem to be some more on ebay, perhaps someone is clearing out a workshop) here is what I found (function on the left, wire colour on the right):

Function	Colour	Atari ST	8833-II
Red (R)	Red	7	3
Green (G)	Light green	6	4
Blue (B)	Light blue	10	5
Horizontal sync	Black	9	8
Vertical sync	Yellow	12	9
Ground	Braid	13	1

I had a few problems at first with getting the two sync wires the wrong way around but once I’d sorted that out it the picture looked great – really clear and bright and the famous ‘little green desktop’ look perfect.

I have a few ideas in mind for this – there’s an interesting project called ‘ACSI2STM‘ which emulates an ACSI hard drive using some low cost components. It does need a bit of hacking around (not least because of the limited availability of the 19 way D connector) but looks like fun. Meanwhile I’ve had a lot of other new toys in so more on those soon…

I grew up in the 1980s at a time when microcomputers were the new thing, and my lifelong interest in technology was really sparked by the excitement of that period. It really did feel as though anything was possible, and rate of change and innovation was far greater than it seems these days.

Over a long period of time I’ve maintained an interest in the tech from this period, and at the time I collected quite a decent amount of kit which I picked up cheap or was given by others. At that time, I was interested in anything I could get my hands on although I rapidly got bored and moved on to the next thing. By the early 1990s I had moved on largely from 8 bit to PCs and the emergence of Linux and the Internet – both very exciting – and so the collection was put away and neglected. I did get heavily into the emulation scene which emerged in the late 1990s and this seemed the perfect combination and so really there was no need for all the old hardware.

I never completely lost interest though and picked odd bits up here and there, but also went through phases where it all felt like a bit of a burden and I got rid of stuff which seemed of no interest, giving some away and selling others. Some of this I now very much regret – eg throwing out a big pile of Acorn manuals, giving away a BBC B and monitor, throwing an Acorn Atom in the bin(!) although to be fair it didn’t work and was missing half its casing. I also had an impressive Commodore PET collection – three in total, plus loads of disks, books, tapes, manuals and other peripherals – that I gave away. The trouble is that at that time (early 90s) it all seemed old fashioned and boring – after all, why try and write text based BASIC programs when you can be running full blown Unix on a 386 PC!

So that was pretty much where things remained for a long time. I had a few boxes full of stuff that I would look at sometimes, but I never really set it up or spent any time with it. I did buy things sometimes if I saw them but usually tired of them pretty quickly.

However, like many people the recent lockdown brought some significant changes. On a whim I was able to buy a Microvitec Cub monitor (as seen on 1980s BBC computer setups) for £6 off ebay:

I already had quite a lot of Acorn kit and so I got it out again to test the monitor… and all of a sudden I found I was really enjoying handling real hardware again. I was also surprised how much stuff I had that I had completely forgotten about and which really I have no idea where it came from.

So this has led me to really dig into my whole collection and I am really enjoying rediscovering what I had and also I’ve started buying more for the first time for years. Prices have gone up a lot (although I think there is something of a bubble caused by lockdown that may not last) but are still within reach.

The other thing I’ve also suddenly realised is that things which were once common and of little value – specifically CRT monitors – are now becoming rarer and are much more desirable than they once were. I never appreciated this before but there is something very authentic about using whole systems from the correct era. It just doens’t look right using LCD panels… so I’ve been buying those too!

There isn’t anything really unique about this but I am going to write some posts about my experiences, including any fixes or upgrades along the way as there are things available now that never were in the past. As usual this is partly for my own benefit and so that I can remember what I did and how I did it… but hopefully of interest to others too!