Increasing Amiga 500 Rev 6A Ram

[RiP]

My Amiga 500 has 512KB trapdoor ram and 512KB onboard but it has 4 empty ram sockets on the board.
Can I fill them to reach 1.5MB or any other cheap way to increase the amount of ram? :confused:

[Oldsmobile_Mike]

Without a lot of hacking, no. Generally the empty socket pads on the motherboard (when populated) use the same address space as the trapdoor expansion slot.

You're better off to get some real fast memory through the side expansion slot. Or look for people to start dumping older accelerators, now that the Vampire boards are available.

[D00kie]

I agree. Some later A500s had a capacity for more chip ram that was later added, and marketed as A500+.

I had an early A500 (1988 but I don't know the rev) that had a trapdoor expansion and there was a hack we did back then where you could cut a trace on the motherboard and get the A500 to configure the trapdoor fast RAM as CHIP ram.

On that basis I'd say the trapdoor ram was in the motherboard RAM address space.

[Pat the Cat]

If you add chips to the motherboard sockets, make sure they are 100ns access time or quicker. 80ns is preferred.

That way, you can do the Agnus hack and have 1MB of chip RAM. AND maybe still fit 3rd party expansions in the trapdoor...

The original CBM A500 512K memory expansion (A501 I think) used slower chips than that, which meant if you used the official CBM upgrade (and paid extra for it) it didn't work for the chip RAM upgrade. I know - I've still got one. The only good thing about them is, they work on all A500s and give extra RAM, but they didn't support modification to chip RAM.

Some A500 RAM expansions had more than 512K, and let you add both extra chip RAM and extra (pseudo) fast RAM - but the Amiga was always built to give priority to chip RAM access, so the above posts are quite correct, if you want performance, add true fast RAM to the slot socket on the side of an A500. Preferably with a big accelerator upgrade too. An alternative way to accelerate the A500, A2000 and even A1000 was to mount internally, on top of the CPU socket, with the original 68K motorola CPU placed next to the enhanced CPU as a backup option. They are much rarer, hard to fit, and typically don't allow much fast RAM expansion, but are much more aesthetically pleasing. Similar accelerators are the ONLY way to upgrade an A600, AFAIK.

Very few people modded their A500 motherboards to use the extra sockets, but with some extra chips (super Denise as well as Fatter Agnus and a 2.04 ROM) you pretty much have  an A500+, although the moulded label on the front still says A500. Adding a Super Denise increases your monitor options, although it will never have the full AGA colour capabilities of an AGA A1200 or A4000.

Some games software and old public domain demos barf at 1MB of chip RAM - they expect the pseudo fast RAM in the trapdoor slot of an A500, and just will not work without it. This is why a lot of the 3rd party A500 RAM expansions have switches and jumpers to change configuration of the expansion.