Re: RAM problem (P500)

From: Marko Mäkelä (
Date: 2006-06-26 22:11:38

On Sun, Jun 25, 2006 at 06:32:16PM +0200, wrote:
> If I POKE from 0 to 2047 I can PEEK back the right value but above 2047 I
> get wrong values back.

If I remember correctly, the B series machines have 2k of RAM in the system
bank ($0 or $f), depending on the model.  Try BANK 1 before PEEKing or
POKEing; that should give you RAM at positions 2..65535.

> Is this a problem with the RAM chips or with the MUX (4 x 74S153).

It could be the RAM chips in the "variables" bank or the MUX.  Again if
I remember correctly, the BASIC program text is in the first all-RAM bank
at 3..65535, and variables are kept in another bank.

I only have a CBM 720, and I only used it to implement the cbmlink transfer
routines for it, some three years ago.


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