Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!van-bc!rsoft!mindlink!a665
From: a665@mindlink.UUCP (Anthon Pang)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 14 mhz Hack
Message-ID: <3357@mindlink.UUCP>
Date: 29 Sep 90 08:14:16 GMT
Organization: MIND LINK! - British Columbia, Canada
Lines: 25

epa@phobos.cis.ksu.edu writes:
> I've seen a few postings lately about placing a 14mhz 68000 in a A500
> and some info files were said to exist on this.  Where are these info files?
> I would also like to hear from someone who has done this modification and can
> tell me the problems/benefits of doing this.

The "creator" is Leslie Ayling.  If the documentation & iff picture aren't
already on abcfd20, I'll ftp them there (about 5K).  The "hack" has only been
tested on a 500, but I believe it'll work on a 2000 as well.  However, contrary
to the docs, it won't work on a 1000, without a Rejuvenator (ie it needs the
28mhz output from the Fat[ter] Agnus), or at least, a few more parts :)

The only problem (as noted in the "accel.doc" files, and postings from
thyssen@batserver.cs.uq.oz.au & martijn@dnlunx.pttrnl.nl) are the:
1) 14mhz clock rate doubles the CIA-B timer which causes the floppy drive to
step at higher rates...such that it doesn't work with normal DOS floppies.
   A few solutions were proposed--reprogram timer interrupts, half the clock
output from the 68000 (E line), or software patch from the author.

Use a D-Flip flop 74ALS74 (equivalent to 74F74).  Also connect pin 14 to the 5V
line.

--
Now will someone please find out what additional parts are needed to get this
hack running on my 1000s...and post the solution to the net :)