Thanks, a friend bought a c64 http://cbm8000.com/IMG_1387_2.png http://cbm8000.com/IMG_1385_2.png For now I only have a small image around the 6569... According to this small image it's either http://www.c64-wiki.com/index.php/File:C64_PCB_Assy250407RevA.jpg or http://www.c64-wiki.com/index.php/File:C64_PCB_Assy250407_Schematic251137Rev B.jpg or http://www.c64-wiki.com/index.php/File:C64_PCB_Assy250407_Schematic251137Rev C.jpg or http://www.c64-wiki.com/index.php/File:C64_PCB_Assy250407_Schematic251137Rev D.jpg I don’t see enough to tell the differences between these boards.. I've forwarded the questions Thanks -- Didier -----Message d'origine----- De : firstname.lastname@example.org [mailto:email@example.com] De la part de Gerrit Heitsch Envoyé : lundi 4 août 2014 22:26 À : firstname.lastname@example.org Objet : Re: mosaic screen on c64 On 08/04/2014 10:02 PM, didier derny wrote: > Any idea why a c64 can only display a mosaic screen an nothing else ? > > Just little colored squares on the entire screen > > Any idea ? Lots of them... But first I would need some information: Board Assy No? Voltages are OK? Any MOS-TTLs on it? Those are the small ICs with a MOS logo and a number starting with '77'. Any IC getting hot? What kind of RAMs does the board use? Maker? If you could supply a picture of the board that's good enough to be able to read the writings on the ICs, that would really help. The usual suspect, unless it's a 250469 board which uses the larg 64pin IC, is the PLA. If it's socketed, try it in a working board. And quite often trying the following will give you some hints. You can use the ROM cartridge without all the wires for basic testing. http://ist.uwaterloo.ca/~schepers/diagnostic.html Gerrit Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2014-08-04 22:00:02
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