Amiga 500 Plus rebuild

[BGL]

After selling off my last proper Amiga six years ago I decided now was a good time to play around with one again.

The older Amiga 500’s (launched in 1987) can usually be found much cheaper than the Amiga 1200’s (from 1993), but most are difficult to upgrade beyond 1MB of chip RAM which can limit what software you want to play around with (most games can be installed to a hard disk using WHDLoad, but this requires more chip RAM than floppy disk load).

The Amiga A500 Plus (from 1991) can easily be expanded to 2MB of chip RAM so that’s the one to go for; the downside being Commodore put a battery on the motherboard, and they are almost certain to leak and cause problems if not cleaned up in time.

Anyhow, one grubby Amiga 500 Plus found with photos of it working, and thus purchased:

…and the battery had indeed leaked so removal and a clean with white vinegar was the first job:

The motherboard is pretty much the same as the earlier A500 and was even used in some A500’s. It’s a revision 8A board from 1991 and contains a the Enhanced Chip Set (ECS) which supports a few more video modes than the Original Chip Set (OCS) which was launched in 1985 on the Amiga 1000. This version also shipped with a new Kickstart ROM version and Workbench - which caused some game compatibility problems, but nothing I’m concerned about.

Cleaning up the keyboard and replacing missing springs and broken plungers was next. This is a Mitsumi membrane keyboard. Legend has it that some early US Amiga keyboard had cherry switches but I have never seen one. Allegedly a Commodore logo instead of the Amiga logo on the bottom left key (next to Alt) is what you need to look out for. If you find one don’t give it away, a collector will likely pay top whack - even a standard spare keyboard is now $100+ on ebay if fully working and not to yellowed.

After cleaning up the keyboard I inspected the rear ports. The mouse port is missing a pin but still works. I’ve ordered a new DB9 port to solder in, but no rush to do it.

Finally for usage as is I needed a new mouse and a VGA adapter (23pin to 15 pin) for my 17" multi-sync BenQ TFT 5:4 aspect screen. These were easily obtained from AmigaKit. A multi-sync monitor is essential as nearly all Amiga games and software is designed for a 15KHz PAL or NTSC screen modes. VGA works at 31KHz and most monitors can only adjust to a slightly lower frequency. Scan-doublers do exist but are either cheap and crap or expensive.

The mouse is a cheap PS2 mouse with a female DB9 adapter and an all important Amiga logo.

More posts to follow.

[FaunCB]

yaaaaay amiga fwend

[BGL]

Because using old 880K floppy disks wasn’t even that nice in the 1990’s (by 1994 I had an A1200 with a 500MB HDD) I wanted a solution to be able to use CF cards. As the A500+ lacks an IDE port (these came in on the A600) I needed to find something that either interfaced directly with the CPU port or the Zorro side expansion port.

Gotek drives are nice in that you can use a FAT formatted USB stick, but you can only work with images of floppy disks - one at a time. So not really wanted, obtaining one still remains an option though.

My searching lead me to three options:

First: a Terrible Fire 530 or 534 CPU accelerator with IDE port, like this one:

The drawback that it sits inside the A500 and is primarily a CPU accelerator (you can build them with a 68030 @ 50MHz and 2 or 4MB fast RAM). Tempting but I’d prefer a hot-swap option. Cost would be around €135 - €200 depending on model.

Second: A Classic 520. This was more like it, a CF port to use as a HDD and a hot swap SDcard FAT32 port. Acceleration provided by a 68020 at 28MHz and 8MB fast RAM but would cost €190 + €45 for a case.

Third: An ACA500plus. This included a CF HDD plus a second hot-swap CF port that can read FAT32 formatted cards. Not only that but a 68000 that can be set between 14 - 42MHz and 8MB of Fast RAM. It also includes another 8MB filled with Workbench 3.1 files and multiple Kickstarts and can simulate an Action Reply III cartridge (great for hacking about). Cost would be €130. So not the fastest in terms of acceleration - but it also includes an A1200 expansion port and further options via clock ports for Ethernet and USB adapters etc.

So that was that, ACA500 plus ordered.

Here it’s upside down, the CF ports, A1200 expansion port and 68000 CPU are visible.

Next was to put it in a case I ordered. This was stupidly expensive for what it is, but does a great job protecting the expansion card so kind of needed.

Fully assembled and installed:

The card’s 68000 runs at a default of 14MHz instead of the A500 native clock of 7MHz and is guaranteed to work up to 21MHz. At 21MHz it performs as well a 14MHz 68020 with fast RAM, so is considerably faster than the stock A500.

For now I have set mine at 28MHz. This is now into playing Wing Commander, Syndicate and Elite2 - Frontier at reasonable frame rates territory.

Next jobs will be to tidy my desk up and set up WHDLoad and copy over some demos, music mods and games

[BGL]

I’ve not really done much with this except discovered a couple of useful points:

1. 25+ year old power supplies don’t work properly - no shit. I’ve got a new build PSU and now I can run the accelerator at 42MHz stable.

2. Amiga disks that have been formatted with the Fast File System and then imaged as an ADF file can be mounted in Linux, very useful. Similar can be achieved in Windows with a few prgrammes but the PC on my desk next to the Amiga runs Kubuntu so…

mount -t affs -o loop diskimagename.adf /mnt/adf

[FaunCB]

Amiga disks that have been formatted with the Fast File System and then imaged as an ADF file can be mounted in Linux, very useful

bruh

[BGL]

Yeah, it’s obvious that it should be possible, just never tried before.

[thro]

Dunno if you’ve seen but there’s a guy on youtube who built one with a new motherboard that some guy has been remanufacturing. need to transplant the custom chips from an old amiga, but then you’ll have a pristine machine with brand new board, new caps, etc.

edit:

I had an A500 back in the day (not plus, this was 1989 when i got it) and very fond memories of the platform. a mate who i sold it to to upgrade to a 486 later got an A1200.

I’ve been on the lookout for an A3000 or A4000 (dream machine of 15 year old me) for a while but they’re worth silly money now… :-\

[BGL]

Yes, he’s done some really good videos, well worth watching. Those purple replcement boards are definately cool though. I think the guy who made them still has a few available for around £50 each. There is also a retired engineer who advertises a full rebuild service on ebay; for £235. After doing that one would be compelled to sign up for the new A500 case and cherry keyboard kickstarters and before you know it you could have a nearly brand-new 30 year old machine for an eyewatering sum

Speaking of which, this isn’t Amiga related (it’s still an m68k series CPU) but have you seen:

[BGL]

I’ve been on the lookout for an A3000 or A4000 (dream machine of 15 year old me) for a while but they’re worth silly money now… :-\

Legend has it that there was a period around 2006-10 when there were quite a few available cheaply on Ebay as TV production companies finally upgraded to new hardware. The Amiga 3000 was always the one I wanted, easily the best designed Amiga with no cost cutting like the A4000 suffered. Another project has released replacement Amiga 3000 motherboards that can also have AGA chipset installed. Nice, although not having an RTG card on such a machine would probably be a crime

[FaunCB]

GIB

ME WANT BAD

AAAAAAAAAAAAAAAAAAAAAAAAaAAAAAAAAA

Thats legit the most amazing machine I’ve ever seen.

[thro]

So uh… i may have just bought an A1200 with 40 meg hard disk, monitor, software, game disks, etc.

missing power supply, but that’s an easy fix… i think.

Might try and learn 68k assembly again. lol. I have a book on it

edit:
bugger, it sold already, within 2 hours

[BGL]

Shame, the A1200’s are in greater demand than 500’s and 600’s but there’s no that much software that was AGA only, and the best releases in the demo-scene that are AGA only also require an 040 or 060 CPU and no one will be getting one of those cheap…

Regardless of if you get one with a PSU or not you need to be prepared to get a new one or open up and recap an old one. As I discovered old capacitors struggle to delivered a stable supply so not recommended. I ended up with one of these, which appears to deliver the juice correctly to the orginal specification (+5v being the primary, not the +12v which is more common these days and the case for converted Cisco PSU’s being sold as ‘Amiga’ power supplies)

https://www.keelog.com/power-supply/

If you are in Europe this seller in Poland does some awesome Amiga 500 rebuilds with Goteks, extra RAM, Kickstarts and SVHS outputs added.

Extreme refurbishing: Episode 4 – Vampiric Amiga 500

His store is here:
https://www.ebay.co.uk/usr/retrocloud-store?_trksid=p2047675.l2559

[thro]

Yeah i thought i might have picked it up, it was $70 and about 15km away, but i was too late

edit:
Yeah, there is a bit of PAL AGA software though, and they’re generally newer, have built in HD, etc. A mate had one when i was a kid, definitely a nice machine to use. But these days you take what you can get

[BGL]

$70, bargain! In the UK people are often paying over £200 for tatty ones with minimal extras. I’ve owned two A1200’s, gave the first one away in 1998, then picked one up in 2010 with an 030 @ 50MHz accelerator but stupidly sold it on in 2012 for £145 as it needed some work and was getting in my way

[thro]

Yeah people want $650 for working A500s here, so definitely it was a bargain. I don’t think the guy knew what he had, but alas… it went pretty damn quick

Will probably see it for sale again tomorrow for $800, lol…

This one had a monitor, mouse, manuals, software… just missing PSU… no yellowing…

[BGL]

I’ll gladly sell my A500 for $650

[thro]

lol. i’m keen on retro computing, but not that keen

[BGL]

I recommend a MIST or MISTer, great way to dabble with retro computers without actually owning one.

[thro]

Yeah, i’ll probably end up with a MIST or MISTER (not sure of the difference, i wanted a MIST and missed out it seems?) - because they do other platforms too.

Still. The Amiga was my first “Real computer” so it holds a special place in my heart.

[BGL]

Agree, nothing like owning the real thing.

No one is making MIST boards anymore, at least not quality ones, it got to a point that those who were doing it professionally (proper QC and meeting environmental laws etc) were being undercut by poor quality clones which drove prices (in an already small market) down, so they quit. Fortunately there are still some proper ones for sale if you know where to look: https://lotharek.pl/productdetail.php?id=97 is where mine came from. For playing Amiga games and demos it works really well, most of the time. I have noticed some quirks - especially when running a 68020 instead of a 68000.

MISTer is sort of a continuation but using a commercially available FPGA boards that in theory allows for more/different ports etc to be added and more powerful CPU’s to be implemented. I believe most new development of new cores is happening there now.