Re: What to do with slow Chip/ST RAM

[mlelstv%serpens.de@localhost (Michael van Elst)]

abs%NetBSD.org@localhost (David Brownlee) writes:

>       It would probably be best to allocate most of the slow RAM to the
>       altmem device on boot and leave just enough to work as DMA space
>       for the devices.

Amiga systems that run NetBSD may have several types of
memory sorted by speed:

- 32bit "local" RAM on an accelerator board.
- 32bit "local" RAM on the motherboard.
- 32bit Zorro-III RAM on an expansion board.
- 16bit Zorro-II RAM on an expansion board.
- 16bit "Ranger" RAM on a special expansion board.

32bit Zorro-III RAM rarely exists except maybe for frame
buffers on graphics cards.

16bit "Ranger" RAM usually conflicts with using an
accelerator board.

and depending on model:

- 32bit Chip RAM
- 16bit Chip RAM
- 16bit non-Chip RAM

Chip RAM == memory controlled by Amiga graphics chipset.
non-Chip == same as Chip RAM but cannot be used by the chipset due
            to lack of address bits.

Chip RAM does not support CAS cycles, any kind of locked cycles do
not necessarily work and you may read or write random bits.


-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."