Re: jeri's board - memory

From: Ruud Baltissen (Ruud.Baltissen_at_abp.nl)
Date: 2001-03-13 08:54:03

If I may add something to the discussion:

> You seem to think that Jeri's board and the SCPU will work
> together.  I've never seen that stated, and some of the
> things I've been hearing make me think that they won't work
> together.

Let's assume that Jeri's board replaces the 6510, seems logical. Using a
6502 means that all other RAM then the original 64 KB is accessed by
bankswitching. Inserting the SCPU disables the original 6510. Therefor
Jeri's 6502 or 65816 will be disabled as well. So IMHO the board and SCPU
work well together on this point.

Accessing the extra RAM on the board may be another matter. I'm not familiar
enough with the SCPU so some things are gueswork and I hope someone correts
me if I'm wrong.
The SCPU has its own RAM. You can tell SCPU what area of the RAM has to be
copied to the original C64 (and when ??). AFAIK I/O is written and read
always. Assuming that Jeri uses some I/O to point to the right page then
there is no problem here. But what area does she use as swap page? If she
uses one (or more pages) inside the I/O area, again no problem. But if she
uses, let's say $C000/CFFF, I have no idea what happens.

Another thing: AFAIK the SCPU can only communicate with Jeri's board at 1
MHZ.

Groetjes, Ruud

http://Ruud.C64.org/

>
> So, I guess we'll have to wait and see.
> --
> Robin Harbron   macbeth@psw.nu
> http://www.tbaytel.net/macbeth
>       http://www.psw.nu/
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