Help identifying what type of Amiga I have?

[Zeela]

bloodline wrote:
Do A500 Trapdoor expansions work in A500+'s at all?

If they don't why do the A500+ have trapdoor? Or it might not have a trapdoor? I've actually never seen a A500+ in real life.

// Zee

[x56h34]

I've heard rumors that Commodore was actually putting A500+ motherboards in A500 cases when the supplies of regular A500 mobos were low. The result of this was an A500 with 1MB chip ram on-board and KS1.3. :-)

Do a google search in groups for more info on this.

[Orjan]

x56h34 wrote:
I've heard rumors that Commodore was actually putting A500+ motherboards in A500 cases when the supplies of regular A500 mobos were low. The result of this was an A500 with 1MB chip ram on-board and KS1.3. :-)

Do a google search in groups for more info on this.

Why on earth whould they do this?

1. When the A500+ was launched, the A500 was already cancelled, atleast to my knowledge
2. If point 1 ( above ) is incorrect, then why would they take 500+ mb´s and put in 500 cases? Why not just build 500+´s instead?

[Linchpin]

I've heard rumors that Commodore was actually putting A500+ motherboards in A500 cases when the supplies of regular A500 mobos were low. The result of this was an A500 with 1MB chip ram on-board and KS1.3.

But what happens then with Hardware Incompatability? People would then think they had an Amiga 500, and get an 512k Expansion card for it, and it wouldnt work (if it was designed for an A500+)

Do you have a link to this info?

Cheers

Kev

[Martyn]

Open it up.

Look at the motherboard.

Job done.

[Linchpin]

On the mobo, there is a stamp.

a500 looks like this =

[Matt_H]

I think 500/500+ trapdoor expansions are pin compatible, but 500 expansions won't work in a 500+ (and vice versa) because of some memory addressing differences. At least, not to their advertised specs.

As for the different models of 500s available, I've got a really strange one: An OCS A500 with a case badge saying "A-500."

I guess the best way to solve the mystery behind this machine is to pop the lid, see if there's anything attached inside.

Something else I just thought of, I think there were some A500 RAM expansions that connected to the trapdoor and Gary, but still had passthrough connectors to attach something else (RTC? One of those PowerPC emulators?). Make sure you're dealing with the genuine trapdoor, and not an extender board.

[nOw2]

But when done booting and WB comes up I have around 900 kb free memory and the trapdoor expansion port is empty.

There are many ways to do this, all involve hacking the hardware.

1. Agnus chip expansion. The Megachip is still available, which replaces the existing Agnus with a plugin board containing a newer (Fat) Agnus and 1.5MB. There might have been older 1MB Agnus versions of this.

2. On the Rev 5 A500s, only half of the 16 memory sockets were filled. With the correct chips, a 1MB Agnus and a soldering iron you can expand to 1MB chip easily.

3. On the Rev 6 A500s, a revised 4 (?) chip RAM solution was used. As I recall, you can still expand this by piggybacking chips on top of each other (to put it simplistically).

Most likely explanation is the Agnus expansion. Open it up, and you should see something like http://www.amiga-hardware.com/dkbmegachip.html sitting in one of the chip sockets.

[Drummerboy]

Hi,

The Best way for know what type of Amiga is opening and check inside the MotherBoard Series Number, and take a look if have any Memory HAck, or came with Memory expansion Socket.. Any A500+ Came with expansion socket for put on a 256k Chips..

Regards!

[Morley]

A friend of mine had a 500 with empty slots inside for DIL memory packages. So we slaughtered a 512KB trapdoor memory expansion which used the same chips (A501?) and soldered them in. I even think there were jumpers or some wires you had to cut/scrape to map these as chip and not fast-ram. Maybe mapping internal DIL's as fast-ram is not possible at all? We did this to be able to load larger modules into Protracker, as 512KB chip memory was not enough for modules >400KB. And when we put another 512KB in the trapdoor it wasn't recognized. I also think there are some connectors on the trapdoor expansion to shut off extra memory, this also affected the memory we just added.

This motherboard was a revision 5 if my memory serves me right, but it is 10 years ago, so I'm likely to be  wrong... The machine was however a KS1.3, not a 500+. It worked nice at the beginning, but the solder equipment we used was not really suited for the job, so over time the machine became more and more unreliable, I think I can blame that on overheating of the memorychips.

Anyway, if you pop off the lid, you can easily see the revision number, and if 1/2 off the DILs are mounted at a later date, you could most probably tell this by some bad soldering or similar :lol:
As I recall there were 8x64KB DILs in originally, with space for another 8x64KB, totalling 1MB, at least on the rev.5 mobo.

-EDIT-

And I think this machine had a Fat-Agnus as standard...the only thing we did was add 128KB DIL's.

[Zeela]

Hi,

I took a quick look under the hood of my A500 this weekend.

What I found out was that it was a A500P.
There was a yellow sticker saying A500P attached to the place where the board revision and model are on the mother board.

// Zee