Accelerator Cards

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no. To upgrade the addressable RAM you need to increase the address space of your board. Solder a net which connects the unused address lines on the 68030 to a RAM controller you need to make your own. There's also the issue of drivers for the OS to recognise that RAM. It's not impossible but definitely out of practical possibility. Get a better accelerator.

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the processor doesn't store anything to a location unless it is given to it by the operating system (in this case, exec.device I believe) you need some kind of program which put the extra RAM into available RAM pool. I think all processor boards have a little ROM in them which contains this, ones that do not, (like derringer) you need to run a program at boot to activate the RAM.

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yes, you get the picture. there are ways to trap the boot process of an amiga and insert these to the available memory pool. Ralph Babel's Guru Book explains in detail, but it's kind of hard to get a legal copy of that book. But you can find *ahem* other *ahem* versions if you know where to look.

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I think they only tried to mean that the accelerator with the most RAM on for A500 had 32 mbs. And they didn't think of viper at the time of writing. There is no such limitation for any amiga (maximum ram on accelerator). A4000's have a 128 mb limit, but that is more related to Zorro3 address space, and any amount above 128mb not being able to DMA by zorro boards, AFAIK.

Chip ram is a completely different thing. It is limited by the chipset and it's inability to address above 2mb. To break this barrier you would need to redesign the whole custom chipset.

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yes. you got it right. The 512k on the A500 is chip RAM. However, the 512k you put on the trapdoor slot of a regular A500 (not A500+) is slow RAM. There's yet another address space just allocated for A500 trapdoor slot which is 1.8 mb I believe (called ranger memory, or something like that). Normal A500 maps trapdoor memory there. This is neither chip nor fast ram though. It is as slow as chip ram, but not accessible by the chipset, therefore called slow ram.

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there are no fixed rules about what kind of processor can be used with an amiga. anything can be used as long as you interact them with proper bus handling. The reason why there are no 060 accelerators for A500 is simply because no one made them, because A500 being the low end of the amiga line, people not being able to afford even and a1200 most probably will never buy a 060 board for a500.

also 68000 bus (A500) and 68020 (a1200) are different in that it is more easy for a1200 to interact with a 68040 bus I belive. But it is possible as there are 68060 boards for A2000, which is a 68000 bus. Theoratically, you can run a PPC accelerator on an A500 with Zorro2 bus expansion, blizzard 2060, PPC developer board.

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I was talking about something like this which gives an A2000 processor slot (Zorro2 is irrelevant), yes it should work.

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well maybe you should see for yourself ?

Amiga 2000 with PPC

An amiga 2000 is basicly an A500 with Zorro2 slots and buster. They have the same 68000 based bus. If it works on an A2000, it should work on an A500.

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you misunderstand. The 68k code does not run on PPC. Only specifically compiled PPC code runs on PPC. The main OS runs on 68k. But some parts (computation heavy stuff like jpeg, mp3 decoding, etc) have special libraries which run on the PPC cpu. This is the case for OS 3.9 (an 68k OS)

OS 4.0 for classics is different though. It runs totally on PPC cpu. 68k programs also run on an 68k emulator on PPC CPU.