orcish75 wrote:

Depending on how the motherboard is configured, you might need to change a couple of jumpers to convert the trapdoor expansion from slowmem to chipmem. There are a lot of articles on Amiga websites on how to do this.

Not just the motherboard, but you also need a certain type of Agnus chip. Early Agnus chips only supported 512K chipmem.
You'll need the newer 'Fat Agnus', which can be found in later A500s, namely Rev 6. This chip has a larger pincount, so you can't easily upgrade an older motherboard with a new chip.

Not just the motherboard, but you also need a certain type of Agnus chip. Early Agnus chips only supported 512K chipmem.

Very true, both my A500s are rev 6 and came with 8372a Agnus chips, which support 1MB chipmem.

OP, look for an A500 that has an ECS (1MB Agnus chip). Rev 6 motherboard A500s are plentiful. You can identify them by checking the ram chips at the bottom of the board. There are usually four 44256 chips (there might be eight of them if the board has been upgraded). The board has Rev 6 Rock Lobster written in a block on the right hand side.

If you come across an A500+ (Rev 8 motherboard), check the motherboard for battery damage before buying it.

Actually, I see orcish75 mentions the Megachip. That's a way to plug a newer Agnus into an older A500.
The small pincount Agnus was only used in the A1000 and early A2000s I believe. I thought they were also used in early A500s, but I think I was mistaken there.
So all A500s have the right pincount, they just don't all have a 1+ MB Agnus chip. The Megachip is a small PCB that plugs into the socket of the old Agnus. It contains a socket for the new Agnus and a bit of other logic (also needs to connect to the Gary chip), which allows you to upgrade the Agnus chip.
After that, you should be able to perform the modifications to the motherboard to make the trapdoor memory work as chipmem.

you have to be careful swapping agnus around as the plcc chips have different pinouts between some versions! dkb megachip is good.

Ugh, seriously you guys... >_<

keropi wrote:

There was another alternative , much easier IMHO: you could get a CF and an IDE->CF adapter for your A600. Then setup WinUAE in […]
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AnacreonZA wrote:

Sorry to interrupt a good flamewar but... […]
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Sorry to interrupt a good flamewar but...

I know I went through quite a process with my A600 to get it to run anything. I got it without any disks at all and had to find some way of writing some from my PC. This was before my CF kit arrived so I couldn't just copy stuff across in UAE and I wasn't going to get a catweasel etc just for that.

I discovered a diagram online for making an LPT to floppy adapter that allowed me to write 880k ADF images across the LPT port to a normal 1.44MB PC floppy drive. I built the cable and sent across an image of an Amiga boot disk. It took me about 10 attempts but eventually one of my boot disks booted my Amiga properly to the command line (AmigaDOS?). Possibly due to me only having 1.44MB HD disks but also probably due to the timing of the parallel port signals.

The boot disk I wrote had software that allowed me to boot the Amiga and link the parallel ports of my Amiga and PC, which would allow me to write ADF images across to the Amiga which would then write the data to an 880k formatted disk in the Amiga's disk drive. I soldered up the transfer cable, figured out how to format a disk in AmigaDOS and eventually created some proper boot disks for the Amiga. That finally allowed me to run a few games.

Quite a mission but a fun one at least. I'd say that if you are getting an Amiga and insist on using real disks you must at least get a boot disk with the machine. Making one from scratch might not be everyone's idea of fun.

There was another alternative , much easier IMHO: you could get a CF and an IDE->CF adapter for your A600.
Then setup WinUAE in a pc and have it use the CF as an amiga HDD.
Using workbench images - or better yet ClassicWB setups - you would partition/format the CF in winuae just like you would with an amiga and when all is done move the CF to the A600 and have it boot to workbench. If you needed to transfer some files/images then all is a matter of using the CF with WinUAE, share a pc folder and make the transfers on the pc. 😎

If you look at the fourth line, he said he did this before he got his cf adapter.

Stiletto wrote:

Ugh, seriously you guys... >_<

I couldn't help but hear that in a camp New York accent. It was very dramatic.

Somehow I think we need Dave Haynie on this forum. He seems like a swell guy.

https://www.youtube.com/watch?v=8jIjBX2ztPs

keropi wrote:

There was another alternative , much easier IMHO: you could get a CF and an IDE->CF adapter for your A600. Then setup WinUAE in […]
Show full quote

AnacreonZA wrote:

Sorry to interrupt a good flamewar but... […]
Show full quote

Sorry to interrupt a good flamewar but...

I know I went through quite a process with my A600 to get it to run anything. I got it without any disks at all and had to find some way of writing some from my PC. This was before my CF kit arrived so I couldn't just copy stuff across in UAE and I wasn't going to get a catweasel etc just for that.

I discovered a diagram online for making an LPT to floppy adapter that allowed me to write 880k ADF images across the LPT port to a normal 1.44MB PC floppy drive. I built the cable and sent across an image of an Amiga boot disk. It took me about 10 attempts but eventually one of my boot disks booted my Amiga properly to the command line (AmigaDOS?). Possibly due to me only having 1.44MB HD disks but also probably due to the timing of the parallel port signals.

The boot disk I wrote had software that allowed me to boot the Amiga and link the parallel ports of my Amiga and PC, which would allow me to write ADF images across to the Amiga which would then write the data to an 880k formatted disk in the Amiga's disk drive. I soldered up the transfer cable, figured out how to format a disk in AmigaDOS and eventually created some proper boot disks for the Amiga. That finally allowed me to run a few games.

Quite a mission but a fun one at least. I'd say that if you are getting an Amiga and insist on using real disks you must at least get a boot disk with the machine. Making one from scratch might not be everyone's idea of fun.

There was another alternative , much easier IMHO: you could get a CF and an IDE->CF adapter for your A600.
Then setup WinUAE in a pc and have it use the CF as an amiga HDD.
Using workbench images - or better yet ClassicWB setups - you would partition/format the CF in winuae just like you would with an amiga and when all is done move the CF to the A600 and have it boot to workbench. If you needed to transfer some files/images then all is a matter of using the CF with WinUAE, share a pc folder and make the transfers on the pc. 😎

Yes - once my CF kit arrived I did exactly that. It is definitely much easier than messing around with floppies. Sadly while removing the CF adapter I managed to snap off quite a few of the IDE connector pins from the A600 mainboard. They were super weak from corrosion I'd suppose and some broke just from me just touching them. I salvaged some pins from a dead board and soldered the new ones in. Probably the most delicate soldering I'd done up to that point, it took me a few hours but I was very happy when the A600 booted up from card successfully again.

^ ah, I really got confused and thought you bought one of the "pcmcia cf transfer kits" and you made a wb boot disk with your cable so you can work with that ... using a hdd of any kind is really the easiest and most pleasant experience, you only go to the trouble to set it up once (really easy with pre-made CWB setups) and then you just sit back and enjoy 😀

I also had broken IDE pins on several A600/1200s over the years... they really cheaped out on every amiga that uses smd components: 1200/600/4000/cd32... As it's been stated before, doing a complete (even if not needed atm) recap on them always pays off in the long run.

Thought I'd provide a happy entry to this thread. Because I'm brassic again (I was flushGamer for a short while) I was unwilling to pay £50+ for a machine that may or may not work properly. There were some really nice boxed items going and some weren't even yellowed! In the end I found a somewhat obscure listing for an A500 60 miles from me listed as collection only, cash payment only. Picked it up last night, I was the only bidder. £30.

The bromine is strong in this one. Nothing a bit of peroxide won't reverse.

By pure luck I've got a rev 6 so that gives me some options. I had to strip it down almost immediately as the floppy drive was throwing read errors for nearly every disk. At first I thought it was media but the drive sounded more like it was seizing so I need to investigate potential mechanical issues.

Also a pleasant / unpleasant surprise:

I'm it's assuming a 512k upgrade. Why does it have a barrel battery on it? It has been immediately removed. The board seems unscathed and the switch was set to off (I'm guessing this is for compatibility). Is this slowmem? Can I remove the chips and solder them to the mainboard to make chipmem if so?

The inside of the case isn't looking so unscathed.

I've not inspected this yet but I think it's part of the keyboard controller. Fingers crossed. Glad I didn't pay anymore!

brassicGamer wrote:

I'm it's assuming a 512k upgrade. Why does it have a barrel battery on it?

It was common to also include a battery-powered clock on RAM upgrades (there was no battery-powered clock as standard on an A500).
The original Commodore A501 RAM upgrade had this: http://amiga.resource.cx/exp/a501
And many clones did as well.

brassicGamer wrote:

Is this slowmem?

Yes.

brassicGamer wrote:

Can I remove the chips and solder them to the mainboard to make chipmem if so?

That depends on various things, including the type of Agnus chip used. You have an 8372A, which should be able to address 1 MB of chipmem. So if the chips are compatible with the motherboard, it should be possible. You may still need to change some jumper/wiring though. I'm not entirely sure about that (there are various different revisions of motherboards and Agnus chips, each with their own quirks), but you could search online, there are some documents available on such mods. Or you could ask on some Amiga forums, Facebook groups or IRC channels. I know a few guys who have tinkered with the Amiga at this level.
Here is some information as well: http://aminet.net/docs/hard/500hacks.txt
The switch on the RAM module may actually have to do with that, allowing you to use it as either fast (well, slow) or chipmem.