Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!ncar!midway!clout!chinet!miroc!reaper!mmm From: mmm@reaper.Chi.IL.US (Michael Marvin Morrison) Newsgroups: comp.sys.amiga.hardware Subject: Re: 14 Mhz Hack Message-ID: Date: 14 May 91 13:11:27 GMT References: <1991May10.104421.22314@rulway.LeidenUniv.nl> Lines: 36 In article billc@cryo.UUCP (William J. Coldwell) writes: >In article <1991May10.104421.22314@rulway.LeidenUniv.nl> breemen@rulcvx.LeidenUniv.nl (E. van Breemen) writes: >> >>To all 14 Mhz hackers, >> >>I have received a lot of mail lately of people who asked me how I made >>the 14 Mhz Hack work. It is very simple, just follow the guidelines of Dave H. > >[DTACK and E-Clock stuff deleted] > >>For me the 14 Mhz started as Hack with one Flipflop and a 12.5 Mhz processor. >>I ended up with a 16 Mhz processor and 7 chips (no wire needed for CDAC). >>This is really a minimal configuration, so all the boards using just 2 or 3 >>chips won't work, it is sad but true. > I would also suggest using a 16mhz 68010. The mere ~5% speedup you see by putting it in at the same clock speed should prove to be even greater at 14mhz. The chip is pin-for-pin compatable, so no change in design would be necessary. One question for anyone.. How does a company go about making the product software selectable between accelerated/normal? Since it's not in a slot, it doesn't have any autoconfig space to tweak a bit at.. I believe my Mega Midget writes to an address in the $c0 space that is unused on a 2000 (slow-fast ram on a 500) to switch between Fast/Normal operation, then executes a reset/stop pair. According to the guru at CSA this stops the '030 and the reset re-starts the system (it's C= reset code with a stop instruction added). I suppose on a '010 system one could use the fc0-2 lines, since on an 010 a fc0-2 of high high low (3) is reserved for user definition (unless it is currently being used by the Amiga). You could trap a 3 on the fc lines as a signal to switch to decelerated mode (using a movec to dfc I believe) -- Michael M Morrison /| |\ mmm@reaper.chi.il.us | | Cash, for Cache.. | | reaper!mmm@miroc.chi.il.us \| Hmm.. sounds fair. |/