C64 Tower ---------------------- Subject: Re: C64 Tower From: Marko.Makela@HUT.FI (Marko =?ISO-8859-1?Q?M=E4kel=E4?=) Date: 08 Mar 1998 14:02:56 +0200 >>>>> "Lorax" == Lorax writes: Lorax> Correct me if I'm wrong (and I'm sure many people will) but Lorax> isn't the reason a Commodore needs the AC voltage instead of Lorax> just straight DC the fact that it has no timing crystal and so Lorax> it relies on the cycling of the AC sine was as its timing Lorax> constant? Well, it would certainly be interesting to build a frequency multiplier that multiplies the AC frequency by 20000, but that is not the case in the C64. The AC frequency is only used for the CIA's Time of Day clock, which isn't used by the KERNAL or BASIC. Some software uses the CIA's clock, for instance GEOS does. If you really need the clock, you can build a 555-based oscillator that generates the 50Hz or 60Hz signal. Another interesting project would be a rack-mounted Commodore pack. Something like a VIC-20, C64 and C16 mounted in a rack, and some switches to select which machine uses which disk drive (the drive(s) could be shared among the computers), to select the video chip (PAL/NTSC; it might be easier to have separate computers for PAL/NTSC, because the switching approach would require replacing the 40-pin video chip and the crystal, which means more than 120 electronic contacts), and the video output (which monitor is assigned to which computer). Also the keyboard could be switchable (one keyboard for all machines, or a separate keyboard for the C16, since its wiring is slightly different). Has anyone done anything like this? -- Marko Mäkelä , http://www.hut.fi/home/msmakela/ Helsinki University of Technology, dept. of Computer Science