atschnei@vlsi.waterloo.edu (Todd Schneider) (06/21/91)
This article was posted in comp.sys.mac.misc .... Does anyone with intimate knowledge of the Mac's timing and a schematic of the logic board think this would work? ========= start of article ============ [My comments in these brackets T.S.] From: pophal@nicmad.UUCP (Gerry Pophal) Subject: Re: 16MHz 68000 upgrade for Plus, SE, Classic Date: 20 Jun 91 17:00:48 GMT In article <13186@uwm.edu> zark@csd4.csd.uwm.edu (Steven M Kosloske) writes: > >A company called MacSource lists a $199 16MHx accelerator for the >Plus, SE and Classic. I called them to ask about this item, and the >tech on the other end told me that they should be available in a month >or so, since they're still ironing out some bugs on it. Supposedly, this >is a direct replacement for the 8MHz CPU. Has anyone heard anything >about this product? > >-- > (Steve Kosloske) | "Speed Racer was disqualified from >------------------------------------| the race because he did not have a > Internet: zark@csd4.csd.uwm.edu | pineapple in his car." - Speed > UUCP: uunet!zark@csd4.csd.uwm.edu | Racer , The Desperate Racer Although I don't know of this product here is instructions to make your own from an article in Info-Mac Digest V7 #230; [stuff deleted] Here are the instructions from the cited article (c't 1/90): -------- start of instructions -------- Cut Pins 11, 12, 13, 20 of the old (8 MHz) CPU. Connect Pins 11, 12 and 13 of the old CPU to ground. [ pins 11, 12 and 13 are active low ... grounding them will take the 8MHz 68000 off the bus. pin 11 - bus grant pin 12 - bus grant acknowledge pin 13 - bus request pin 20 is the E clock, a clock used by peripherals for timing. ] Solder the new (16 MHz) CPU *upon* the old CPU (it's not necessary to remove the old CPU), except Pins 11, 12, 13 and 20, which are directly connected to the motherboard, and except Pin 15, which receives the clock rate (16 MHz) from Pin 19 GLU (Mac SE) or Pin 8 of the quartz oszillator (Mac Plus) via 3 inverters 74LS04. [ New CPU is clocked at 16MHz ... peripherals receive E clock from the new CPU. The 3 inverters are used to delay the clock by 3*Tpd + 1/2(Tclk) ... why? ] You will have to experiment with the exact number of inverters needed. -------- end of instructions -------- [ more stuff deleted ... original author comments that it is translated from German ] Thanks in advance. -- Markus. Bitnet: ug142bc@DM0LRZ01 Markus Fest Fachbereich Mathematik Ludwig-Maximilians-Universitaet Muenchen ------------------------------ -- UUCP:harvard-\ att--\ | Sysop Mad Mac BBS(608)221-3841 ucbvax!uwvax!astroatc!nicmad!pophal | Gerry Pophal(608)271-3333ext2091 rutgers--/ rolls--/ | Nicolet Instrument Corp. ames--/ decvax-/ | Madison, Wis 53711-0451 ========= end of article ========== Any comments from the 68k/Mac hardware gurus out there? Maybe I can borrow a friend's Mac to try this out ;-) T. -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- + University of Waterloo | atschnei@vlsi.waterloo.edu + + Department of Electrical Engineering | atschnei@vlsi.uwaterloo.ca + + VLSI Group | Office:(519)885-1211 x3896 +