U267105%HNYKUN11.BITNET@wiscvm.wisc.EDU (02/11/87)
Date: 11 February 1987, 14:59:00 MET From: Jos Grote Punt 080-566793 U267105 at HNYKUN11 To: INFO-CPM at AMSAA-SEER Recently I received a CP/M cartridge for the Commodore 64. I know everyone would advise me to use a C-128 to do CP/M, but at the moment I have no money to buy one. I got this strange problem: on some machines the cartridge works, on others it doesn't. And every time the 64 hangs at an other moment, sometimes after 1 asterisk (there's an asterisk for every sector that gets loaded during a cold boot), sometimes after 3 or 4 (there should be 28 !!). Does anyone know about differences between individual C-64's ??
mwilson@pnet01.CTS.COM (02/12/87)
There was a problem with early versions of the 64 and the CP/M cartridge. It had to do with timing differences between the video chip and the Z80 in the cartridge. Newer 64's have newer VIC chips, and the problem doesn't show up. Your CP/M system may also be glitched. Does the drive light blink when booting?
prindle@nadc.arpa (02/12/87)
The reason that the CP/M cartridge works on some 64s and not on others is that newer 64s have an improved VIC II chip which produces proper NTSC video (the old one had a bug and divided a clock by 64 instead of 65, or something like that, which produced garbled color video). The newer chip produces a slightly different (1 or 2 percent) processor clock timing and the CP/M cartridge fails to operate correctly. The only cure is to use an older VIC II chip - if you are using a Commodore 1701/1702/1802/1902 monitor with the separated video input, the old chip looks as good as the new one. Only the composite video is screwed up. Thus, if you have a friend with a C64 with the old VIC II chip but no CP/M cartridge, do both of you a favor and trade chips with him - he gets a better composite display if that matters, and you get a working CP/M cartridge. The VIC II chip is the large chip to the left side under the metal "can" - it has a blob of heat-sink compound on the top that a spring presses on when the cover is replacd. Sincerely, Frank Prindle Prindle@NADC.arpa
jdb@ncsc.arpa (02/12/87)
The current issue of RUN (March 87) has a response to a letter to Commodore Clinic on a different subject (problems with the ram expanders on early C128s) which hints at a similar problem with the C64 CP/M cartridge. The letter and response are on page 92 The guy with the ram expander is treatening to sue or turn them in to the Federal Trade Commission for false advertising. The answer says that Commodore had some trouble with the Feds over the C64 CP/M problem and promised they would stop advertising products and features not actually available. Maybe you have some legal recourse if one of the C64s that won't run the CP/M is yours. You might even get Commodore to replace yours (but its doubtful) if you threaten to bring this up with the FTC again. David Brown jdb@ncsc