A500 revisions

Hey guys!

I have an A500+ here and I'm not really sure what kind of combination it is supposed to be.

The casing is that of an A500+; it has the wider badge recess and says A500 Plus, so that's all well and good. There is also a switch on the side to disable the trapdoor memory.

Now the trapdoor memory also has an RTC on it, and a battery that has leaked. The motherboard is a rev. 8A and has all the relevant RTC circuits on it... but none of those components are actually installed. This is mainly a good thing of course, as there is nothing that needs cleaning up.

Also on the memory area only half of the chips have been installed, the Denise is a 8362, and Kickstart is 1.3. It would seem like this is something that Commodore built to be an A500, but used the newer motherboard. Doesn't really explain the case though, surely they can't have sold it with the Plus badge.

However, the Agnus is an 8375 (390544-01) which I believe is a 2 megabyte model. This is what I was mainly after, so pretty happy with it.

Anyway, any guesses as to how this kind of system has come to be together? Is it simply that the case has been changed afterwards?

Also, if I put an Indivision ECS in here, does it make any difference that the Denise chip is an OCS model?


Thanks!

The Big C= did release a bunch of A500s using the r8A (A500+) motherboard. How much Chip RAM is on the board (ignoring the trapdoor)? If it's 512K, it's an A500 board in an A500+ case. If you've got a full 1MB, it's an A500+ where someone has stolen the Kickstart and Super Denise.

Well as there is no RTC or any of the relevant capacitors and crystals installed (never have been as far as I can tell, or someone did a darn clean desoldering job), I would imagine this is an A500 rather than a Plus. But they have still graciously put in a 2 meg Agnus :) Only half of the motherboard memory slots are populated, as I mentioned.

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Originally Posted by ajk

Well as there is no RTC or any of the relevant capacitors and crystals installed (never have been as far as I can tell, or someone did a darn clean desoldering job), I would imagine this is an A500 rather than a Plus. But they have still graciously put in a 2 meg Agnus :) Only half of the motherboard memory slots are populated, as I mentioned.

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That's unsurprising. It's not uncommon for a last-revision A500 to have an 8375 Agnus. I suspect all the r8A boards have that Agnus. :-)

Time to solder a few memory chips, a multiplexer and redo a few jumper bridges to make it an A500+, then.

A Super-Denise will come in handy, but they are expensive to buy.

Don't mind the RTC circuit, as it is only useful for HD people.

Any 2.04 ROM will also make wonders to this Amiga!:)

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Originally Posted by rkauer

A Super-Denise will come in handy, but they are expensive to buy.

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I'll avoid price-driving, but suffice it to say that it's quite possible to get a Super Denise for not-a-lot. :-)

Gimme! :)

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Originally Posted by rkauer

Any 2.04 ROM will also make wonders to this Amiga!:)

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Go straght to 3.1 ...

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Originally Posted by ajk

Also, if I put an Indivision ECS in here, does it make any difference that the Denise chip is an OCS model?

Thanks!

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Nope, I think Jens did that just to differentiate the different models (ECS, AGA).

Indivvy will only take what Denise is outputting to video, and apply its own funky stuff, and output a new picture via its OWN connector.

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Originally Posted by whiteb

Indivvy will only take what Denise is outputting to video, and apply its own funky stuff, and output a new picture via its OWN connector.

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So ECS modes will be available even with the OCS chip? This is what I had understood, I just wasn't sure. Makes sense though if most of the logic has been recreated in the FPGA. Cool :)