Saturday, December 15, 2018

Which one's best? There's only one way to find out!

A reasoned debate based on empirical evidence and documented experience...

There are a lot of retro computer collectors out there. There are several reasons I know this.

First, there are a lot of them on Twitter and one or two may actually follow me there. I certainly follow quite a few.

Second, the price of retro stuff, and in particular Amiga items, has skyrocketed in the last three or four years as more and more people start collecting. Supply and demand and all that.

To give you an example, I paid around £170 for an A1200 in a Micronik tower (the all plastic one) with a Squirrel PCMCIA SCSI interface and four speed SCSI CD-ROM drive. This was in 2015. Today, on eBay, a stock A1200 that hasn't even been re-capped will set you back at least £200. A CD32, boxed, re-capped and fully working with a controller will set you back at least £400. And that was it's original retail price in 1993!

With the continued inflation of Amiga prices I have been unable to buy many things (under penalty of divorce) so I have had to go with several other systems, some I already owned but mostly acquired from lucky bids on the aforementioned eBay. It got me thinking that someone who is setting out to acquire some retro computer kit may not know where to start or which machines are good to begin with and which are not.

So, what follows below is my own meandering experience of retro computers. It is not intended to be definitive or instructions on how to collect. Nor is it intended to be a tutorial for repair or anything like that. Take it at face value.

Let get on with it. Machines what I've worked on (click on the titles to take you to a blog post):

Amiga A500 and A500+
Although prices for A500s are rising, possibly due to the limited chance of getting an A1200 for a decent price, but also possibly because Vampires are now available for them, they are still a good machine to start with.

My own A500+ with hard disk & external floppy.
Battery damaged board but repaired.

If you're completely new then try and avoid cheapish looking A500+ models. These will almost certainly have battery damage from the dreaded Varta that was installed on the Rev 8 models. This is shown by green corrosion and fuzz around the normally blue battery casing on the motherboard. The more sharp eyed will also spot that the trapdoor connector usually also shows signs of the green rot too..  Unless you get one that specifically says the battery has been removed and cleaned up then stay away. Perhaps you like a challenge...

Other common faults with A500s are busted CIAs resulting in dodgy mouse or joystick control, and the failure of the floppy drive. These are normally straightforward fixes. These units also have a terrible problem with going yellow in the sun which is a common issue with most beige electrical kit of this sort of age.

Software is (was) relatively easy to find but might become harder now that Nintendo have started to come down on ROM sites.

A hard disk is a good thing to have but original units are also getting quite rare. Something like a GVP or AlfaData AlfaPower drive will add an extra level of functionality. The AlfaData external units also can come with Fast RAM (essential for WHDLoad) and are IDE units allowing the use of cheap Compact Flash card adaptors.

A500+ Motherboard

Repairability:  8/10
Most chips are socketed and it's easy to open up and have a good poke around. Very rare to have a capacitor issue on these too.
Price: 7/10 
They're going up! Expect to pay anywhere from £35 to £90.
Overall Collector Score: 8/10

Amiga A1200
The successor to the A500 (I will ignore the ridiculous A600) and with extra RAM, a slightly faster processor and the new Advanced Graphics Architecture (AGA) chipset, these are very, very desirable. Accelerators are were relatively easy to find (but getting harder) and can add a level of 'oomph' that I only dreamed of in the early 90's.

It' A1200

The A1200s (and 600 and CD32) suffer from the problem of cheap capacitors. They are surface mounted pots of electrolyte that leak over the board and slowly eat away at the copper traces. They can cause the complete destruction of a motherboard so, again, if you're picking one up for the first time, you should check for if it's been seen to. There's no battery in the stock A1200 but if you're lucky enough to get one with an accelerator card in it then there's a good chance there's a battery on there - remove it quick!

Capacitors not sitting flush.
Danger Will Robinson!

Price is the main problem here. As I mentioned above, a stock A1200 will set you back around £200 which will probably not even be re-capped. For that price it's 50/50 as to whether you'll need to break out that soldering station and get fixing.

Repairability: 6/10 
It's all surface mount in there so you need a steady hand or specific equipment..
Price: 6/10 
I love these machines but who in their right mind would pay that much for them?? Expect to pay over £200 for even the most 'untested' of machines..
Overall Collector Score: 6/10

ZX Spectrum 48K
The venerable ZX Spectrum was the first computer that our family owned. In actual fact, we had a ZX Spectrum+ which was a slightly improved 48K model but which also had a half decent keyboard with a space bar in the right place and a reset switch.

Spectrum 48K Interior
This is an Issue 2 motherboard

As with a lot of things on this list, capacitors can be a problem. In this case they're all 'through hole' and so easier to work with but, be warned, the boards of the spectrum are more fragile than later machines like the Amiga. Exercise care if you decide to re-cap.

Other problems include broken RAM. This is normally caused by the failure of the voltage regulator on the motherboard or the DC-DC circuit that generates 12 volts. The lower portion of RAM requires +5v, -5v and 12v to operate correctly. Any missing voltage will damage the RAM. It doesn't even need a complete failure to cause this either. Look for garbage on the screen when it starts.

The ULA (Uncommitted Logic Array) chips can also die in these so, if you can, try before you buy.

Certain motherboard revisions benefit from later mods. For example, the issue 2 - which has its heat sink located in the bottom right of the motherboard - can have a mod added to the DC to DC circuit which improves resilience to voltage spikes caused by unplugging expansions with the power still running (don't do it!).

Finally, the keyboard membranes regularly fail due to their age. Fortunately new ones are available and tend to be made from modern materials which should improve their durability.

Broken keyboard membrane

Repairability: 7/10
Everything is through hole so a standard iron and a steady hand is all that's needed. Just be careful of the slightly more delicate traces!
Price: 9/10
Spectrum 48K models in an 'untested' state can be had anywhere from £20 so they won't break the bank. Get one with a tape cassette player and cables if you canA great place to start and a fine piece of history too. Also consider the +2 and +3 models although they tend to be much more pricey - especially the +3.
Overall collector score: 8/10

Amstrad CPC464
To be honest, the first CPC464 I owned was acquired only a few months ago. In fact, I actually bought two as part of a job lot of stuff which included the Plus4 (see below). I was very pleasantly surprised to see their build quality, not a thing Amstrad has necessarily been renowned for, and was very happy that they both 'just worked'.

CPC464 - Later model with angled stripes on logo
My dodgy camera makes this look bent - it's not

If you get one of these the first thing you should do is change the cassette drive belt, unless it has already been done. This is always the first thing to perish as it is, after all, basically a glorified rubber band (don't be tempted to use a rubber band though - it won't work and could make things worse!).

I have seen no major reports of problems with the chips in these things. General issues could be caused by a dodgy RAM chip or a potential ROM problem but, overall, these things seem to be bullet proof. And there are no electrolytic capacitors to worry about! Every capacitor is ceramic. :)

They do use a membrane keyboard on all but the earliest of units, but the two I had were still using their original membranes and all the keys worked with no issues at all.

You could also consider modding these to accept a MIC input which will allow the use of *.TAP files to load games from your phone or favourite generic MP3 player rather than physical cassettes which is easier and can be a bit faster too.

Repairability: 9/10
A few screws to undo and easy access to everything on a good quality PCB with all through hole components. Nice.
Price: 8/10
Expect to pay about £40 to £50 for a working CPC464 without a monitor. If you find one that comes with a monitor then add another £40 or so for monochrome or £60 to £80 for colour. Other models like the CPC664 or CPC6128 are also around but expect to pay a premium for their floppy disk capability.
Overall collector score: 9/10

Commodore Plus 4
The Plus4 is an odd beast. Released as a 'replacement' for the C64 despite not having the famous SID chip for sound, reliable components or good software support, it unsurprisingly failed to capture the previous glory that Commodore enjoyed with the C64 or even the venerable Vic20. It was reasonably successful in Europe which provided some relief to the sales guys at CBM but failed miserably in the US.

Full disclosure. These things fail. A lot. They have a non-standard variant of the 6502 processor known as the 7501 (early) or 8501 (later). When they were produced mistakes were made in the production and design and so these chips die just through normal use. Some died within hours, some within months. Some lasted a bit longer but most will die soon.

They also have what is called a 'TED' chip. These things also die. And are almost impossible to find replacements for.

If you're tempted by one of these and end up getting one, the first thing you WILL need to do, assuming it works, is take it apart and put the biggest heatsink you can find (and fit in the case) on both the CPU and TED. The ROMs can get quite hot too.

Plus 4 interior carnage
CPU - DEAD (replaced with 6510 adaptor board)
8551 serial chip - DEAD
RAM - 2 chips DEAD
Plus4 ROMs - DEAD
If you have one with a black screen then you're too late. You have either a faulty CPU (75% chance) or a faulty TED (25%) chance. Garbage on screen could indicate faulty RAM or, as was the case with my own Plus4, the 8551 interface chip was spewing garbage on to the main data bus causing all sorts of bizzare things to happen.

I would not recommend this to a beginner collector, which is a shame as I like the design and there are some cool things you can do with them including an SD2IEC implementation - this is Commodore kit after all. But the chances are if you get an untested unit it will not work and those replacement chips are getting more expensive IF you can find any. The CPU can be replaced by a 6510 (as in the C64) with an adaptor board but there are a couple of technical limitations i.e. the computer won't be able to directly control the tape deck, the tape deck motor runs constantly, a new Kernal is required - but this is normally supplied with the adaptor board.

Repairability: 4/10 
Nice and easy to get into, nice and easy to remove the dead chips. Shame there's not much to replace them with...
Price: 6/10
These units are going up in price for some reason. I would not consider paying more than £30-40 for a working unit. Chances are, if you start it up, it will work for five minutes then become a non-working unit anyway - get those heatsinks in and pray.
Overall Collector Score: 4/10

Apple Mac Classic II
This one came to me via a nice chap in Worcester and I'd originally intended to restore it and use it 'properly' but, sadly, I had to sell it on. These units come with a CRT monitor built in so any repair work needs to be treated cautiously as these things hold high voltages and currents that can kill.

Early Mac
Units like this one appear on eBay regularly but be careful about battery damage. They have a small lithium non-rechargeable battery on board which can leak and completely destroy the main board. Caps are also an issue, similar to the Amiga A1200 (and A600 etc) being the surface mounted electrolytic type. The motherboards are good quality though, and the unit I had the motherboard went through the dishwasher(!) with no ill effects.

The biggest issue with these things is getting the software. Unless you have an older Mac that has both floppy drive and USB then you will struggle. While I was restoring this unit I inadvertently managed to wipe the first 1MB of data from the main partition of my Windows 10 PC, rendering it er..dead. So proceed with caution if you're forced down the PC route for disk preparation.

Finally, the hard disks on these units die very easily. If you get a unit with a working drive, do not trust it. Fortunately, the Mac Classic II uses a standard SCSI interface so any drive of an appropriate size will do but - again - be aware that you'll need third party software to prepare the drive or a patched version of the Apple software. Apple helpfully wrote their software to only work with Apple branded hard disks... the more things change, the more they stay the same.

Repairability: 6/10
Surface mount stuff but the boards are hardy beasts as long as they have avoided battery damage. Be prepared to lose hair and sanity when trying to get the software working though. AND STAY AWAY FROM THE HV CIRCUITS IN THE CRT!!
Price: 7/10
Not too expensive these days for an 'untested' unit. Expect anything from £20 to £80 depending on condition and whether or not the buyer has to ship it. If you can, find a local one so it can be safely belted into the back of your car.
Overall Collector Score: 6/10

As with all things like this, your mileage may vary. Prices vary wildly on eBay to the point of insanity. My favourite is the guy in Scotland who puts his standard A500 (ready to go! UNTESTED) on eBay every so often for £1000. Yes, a grand. The popular theory is that he's been told by his other half to get rid of it and is 'going through the motions'.

Finally, if you are looking to start collecting retro game systems then, good luck, don't spend too much (unless you want to) and enjoy the systems for what they are.

Merry Christmas!

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