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.
