Re: proposal: millicode

[Frank Wille <frank%phoenix.owl.de@localhost>]

Ignatios Souvatzis wrote:

> On Sat, Jan 19, 2008 at 09:02:33AM -0700, Tim Rightnour wrote:
>> 
>> On 19-Jan-2008 Ignatios Souvatzis wrote:
>> Because at that address there is only Slooooooooooow RAM. You don't want
>> to use it for anything else but DMA buffers for the audio device, the
>> built-in graphics, and the built-in floppy, that are connected to it.
>> 
>> Where is that ram range on amigappc?  How far up does it extend?

The slow RAM (called "Chip-RAM") is from 0 to 0x1fffff (2MB). After that we
have a gap, followed by memory-mapped I/O and the ROM. All below 0x01000000.


> THose are Amiga 3000 and Amiga 4000 machines with on-mainboard fast
> ram from 0x7000 0000 to 0x7fff ffff (max) and CPUboard RAM from
> 0x8000 0000 up, where the last 512 kBytes are also (or instead -
> I'm not sure) accessible at 0xFsomething, so you can put PPC trap
> vectors there.

Although 256MB onboard RAM would be nice, it is only 16MB from 0x07000000 to
0x07ffffff. And a maximum of 128MB on the (PPC) CPU board at 0x08000000.


> There are alos Amiga 1200 ppc boards, that have the RAM somewhere 
> else.
> 
> Frank will know the exact numbers by heart, I guess ;-)

Not really. I never owned an A1200, but I heard there are CPU board revisions
with different locations, mostly in the 0x60000000 area.

Of course, all that is not really important when regarding the current state
of the port. But, when possible, Tim may want to keep it in mind.


-- 
    _  Frank Wille (frank%phoenix.owl.de@localhost)
 _ //  http://sun.hasenbraten.de/~frank/
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