Re: C64 GRAPHICS CARD

From: Hatch (hatch_at_in.com.au)
Date: 2005-02-03 14:56:30

Fixed up that problem with the static ram.  I took a look at how Nicholas
Coplin interfaced the static ram on his Auto-RAMDOS project (Haven't seen
him post on here for a while, anyone know what he's doing?), anyway I hope
he doesn't mind me getting ideas from his design.  I was using either phi 1
or /phi 2 for /WE and Nicholas used /RW (I know this was the most obvious
way to do it but I actually didn't think the holding /WE low for the entire
write cycle would be valid).  Nicholas used /phi2 for /CS1 and I was using
RW.  So after rewiring the control signals to the RAM using the same control
lines as Nicholas had used I was ready to do another test.  It still had the
same problem (but less often, now only about every 4000 writes).  I ended up
fixing it by delaying the /CS1 signal to the RAM by sending the signal
through a couple of NAND gates and now the cct works fine, Nicholas used a
74HC139 in his project, maybe that delayed the /CS1 signal enough?  I wonder
if Nicholas had a similar problem when he designed his project?

By the way there where only two examples I could find of a 6510 connected to
static ram, one was Auto-RAMDOS and the other was the UltiMax designed by
Commodore.

I guess the next step for me is to decide on what features will go into the
redesign of the video cct.

----- Original Message ----- 
From: "Nils Andreas" <andreas@wiwi.uni-frankfurt.de>
To: <cbm-hackers@ling.gu.se>
Sent: Thursday, February 03, 2005 12:18 AM
Subject: Re: C64 GRAPHICS CARD


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