Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!hc!lanl!unm-la!unmvax!nmtsun!caasnsr From: caasnsr@nmtsun.nmt.edu (Clifford Adams) Newsgroups: comp.arch Subject: HACF (was Re: Risky instructions) Summary: More fun with BASIC Keywords: history, pc, PET Message-ID: <932@nmtsun.nmt.edu> Date: 13 Aug 88 21:24:07 GMT References: <5458@ecsvax.uncecs.edu> <1876@looking.UUCP> <753@applix.UUCP> <5440@june.cs.washington.edu> <1239@ficc.UUCP> Reply-To: caasnsr@nmtsun.nmt.edu (Clifford Adams) Organization: New Mexico Tech, Socorro NM Lines: 28 In article <1239@ficc.UUCP> peter@ficc.UUCP (Peter da Silva) writes: >If anyone out there has a Compucolor-2 (a Z-80 based PC from the early >'80s) you can implement HACF from Basic: >10 FOR I = 1 TO 255: OUT 6,I: NEXT An even shorter sequence was possible on one model of the Commodore PET personal computer. All that was needed was to place a certain value xxx into memory location yyy. Several hours later one of the video chips would be dead. The instruction was: POKE xxx,yyy Apparently the value yyy would put the chip into an adjustment mode, which increased the frequency of a certain function. Faster and faster.....till meltdown. What was really interesting is that COMPUTE! magazine (back when it was good) had an article about this function, *giving the exact values for xxx and yyy*! (perhaps that's why I can't find any PETs :-) >Peter da Silva, Ferranti International Controls Corporation, >sugar!ficc!peter. -- Clifford A. Adams --- "I understand only inasmuch as I become." ForthLisp Project Programmer (Goal: LISP interpreter in Forth) caasnsr@nmtsun.nmt.edu ...cmcl2!lanl!unm-la!unmvax!nmtsun!caasnsr