Hello, JFTR: * On Sun, Dec 11, 2011 at 09:04:07PM +0100 Gerrit Heitsch wrote: > On 12/11/2011 08:28 PM, Spiro Trikaliotis wrote: > >Hello Gerrit, > > > >* On Sat, Dec 10, 2011 at 09:14:03PM +0100 Gerrit Heitsch wrote: > >>On 12/10/2011 08:51 PM, Segher Boessenkool wrote: > > > >>I don't plan on using the 6569R1 regularly. But it's nice to have a > >>really old C64 (includes real PLA and -02 Kernal ROM) handy when > >>checking software compatibility. The RAM test I use crashes on the > >>-02 ROM, plug in a -03 ROM and it works. > > > >Why does it crash on a -02 ROM? I mean, the differences between -02 and > >-03 are very small. > > I asked myself the same thing but didn't see a reason to investigate > in detail yet. The problem was reproducable though. Looking into the code, it is obvious: The code writes directly into Video RAM ($0400-$07FF), but never writes the color RAM ($D800-$DBFF). As the -02 ROM initializes the Color RAM to background color, you do not see the output. Workaround: 1. LOAD the RAM test 2. CLEAR SCREEN 3. POKE 53280,0:POKE 53281,0 (I assume you did not have black as your background, otherwise, use another color) 4. RUN the code Voilą. BTW: The test is extremely simply and would not find many erroneous RAM chips, anyway. Regards, Spiro. -- Spiro R. Trikaliotis http://opencbm.sf.net/ http://www.trikaliotis.net/ http://vice-emu.sf.net/ Message was sent through the cbm-hackers mailing listReceived on 2011-12-11 22:00:11
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