Maximum RAM in an Amiga 2000??

[Zac67]

What happens if the CPU takes an odd number of cycles to complete an operation?

Nothing special, since a single CPU cycle consists of two bus cycles.

[amigaksi]

Nothing special, since a single CPU cycle consists of two bus cycles.

There's some timing map in the HRM that has the memory cycles as being same as color clock cycles (3.58Mhz) which means 2 cycles of the 7.16Mhz crystal.  Move.w D0,D1 or NOP instruction is 4 cycles since it's 2 cycles for fetch and 2 cycles of internal operation when bus is free.  So I guess you meant the reverse.

[rkauer]

You guys just don't answer fully the question:

There are four types of memory an Amiga 500/2000 can have:

 -Chip RAM, which is shared with the chipset & CPU: 512kb, 1Mb, 1.5Mb or 2Mb, pending the Amiga model and the Agnus version;

 -Slow RAM: up to 1.5Mb in an unused chipset address. Only saw the light of day in A500 models;

 -Zorro-2 memory: up to 8Mb, need memory boards or memory+controllers board combos (A2091 and GVP SCSI+8, for example).

- Local FAST RAM on accelerators: Up to 128Mb, pending the model. Some very old accelerators put the memory addressing inside the Zorro2 space, limiting the total amount of FAST RAM you can have on a system.

 An example of the later is the GVP Impact A3001, which puts its memory in Zorro2 space, making the A2000 "only" 1+8Mb.

[Zac67]

@rkauer
Add to that 32 bit Z3 RAM and you've got a list. And on the 1200 you may have 256 MB accelerator RAM.

@amigaksi
Depends on how you define things (I'm differentiating bus cycles and clock cycles) - but the 68000 can only utilize half the bus bandwidth, so if the chips use no more than the other half, there's no penalty.

[rkauer]

@Zac: Zorro 3 on A2000?

[TheBilgeRat]

@Zac: Zorro 3 on A2000?

No-he was meaning in addition to the list above, add 32bit Zorro 3 ram, as in ZorRam expansions for Z3 slots

[Zac67]

Oops - must've missed the "500/2000" part, sorry!

As a side note: accelerator RAM on 500/2000 is not limited to 128 MB (only by existing boards). Since the mobo provides no installation help, adding 32 bit RAM needs to be done 'manually' (boot ROM) regardless of size.
On the 3000/4000/1200 the system supports automatic installation of 128 MB (1200: 256 MB) with no additional logic on the CPU board.

[psxphill]

You guys just don't answer fully the question:
- Local FAST RAM on accelerators: Up to 128Mb, pending the model. Some very old accelerators put the memory addressing inside the Zorro2 space, limiting the total amount of FAST RAM you can have on a system.

This was omitted because the OP said without an accelerator.
 
In the old days you had to put fast ram within the first 16mb, or devices with dma would get upset. It was only later that commodore allowed you to allocate memory where the address would fit in 24bits.
 
Annoyingly with an accelerator with local ram in the zorro 3 space, your zorro 2 dma is going to have to use chip ram. Unless you also have some zorro 2 fast ram.