Amiga 500 ram?

[Kronos]

The A500 has 512KB RAM onboard and  trapdoor-slot was designed to host another 512KB.

The A500+ has 1MB RAM onboard and  trapdoor-slot was designed to host another 1MB.

Putting a card designed for the A500 into an A500+  gives you 1.5MB (working) and 2 conflicting clocks.

Putting a card designed for the A500+ into an normal A500 just won't work.

A 512KB card for the A500 should cost no more than 20Euro (if it's more, better search for an A500 with a card fitted at that price).

There are some special cards that are designed for the A500 and carry up to 1.3MB but those would be rather hard to find.

[Kronos]

@Lord Aga

AFAIK there are no new (Chip)RAM-expansions available for the A500+, but the one S0nic showed in his 1st post would do the job quite nicely.

@S0nic

Yep, that one would be o.k.

[Kronos]

@LordAga

Cos the A500+ allways has an Agnus capable of addressing 2MB chip, so all 1MB expansion were made to appear as extra chip.

Non+ A500 might contain an orginal "Fat"Agnus only capable of addressing 512KB chip, so the trapdoor was designed to host 512KB of SlowMEM.

Later revisions of the A500 contained either an 1MB Agnus or even an 2MB Agnus (these were really just downgraded A500+ mobos) at which point it made sense to use the extra 512k in the trapdoor as chipMEM.

If you A500 came with an 1MB Agnus standard it's as simple as changing one solder-jumper (JP2 left of the 68k AFAIR) and switching the 512k-expansion of (so it wouldn't be regognized twice).