[sebhc] 444-66

Jack Rubin jack.rubin at ameritech.net
Sat Jun 19 18:41:46 CDT 2004


Whatever is easiest for you works for me - the goal really is to keep
the information in circulation. I've set up the SEBHC archives for
limited distribution to minimize the chance of "publishing" something
that really isn't public domain. Obviously how you handle your own
material is up to you - and giving it maximum exposure is great. Maybe
you can get some of your students to take a look at the 8-bit world.


> -----Original Message-----
> From: sebhc at sebhc.org [mailto:sebhc at sebhc.org] On Behalf Of Peter
> Sent: Saturday, June 19, 2004 6:11 PM
> To: sebhc at sebhc.org
> Subject: RE: [sebhc] 444-66
> The trick with speeds over 4MHz was to implement speed 
> switching in the OS. When the computer needs to access 
> certain hardware, I would have it switch to 2MHz operation 
> till the I/O was completed. This was not necessary for a 4MHz 
> mod. Although I have not done it successfully myself, I have 
> had reports of some users running at 8MHz. I don't remember 
> any more who did this - it was quite a while ago.
> As for the 444-66 source, I do not have it. The units I have 
> were simply copies from the original but burned to higher 
> speed PALs. I do not have equipment to do this - I contracted 
> another person for these parts. They only cost a few dollars 
> apiece. I totally forgot about them till just now. I also 
> found my stash of 74HCT00 ICs that were also a necessary part 
> of the speed upgrade process.
> I just got back from moving my daughter into an apartment for 
> the university. As soon as I get organized a bit, I will try 
> to post the information for increasing the CPU speed - 
> perhaps it might be easiest to put it on my own website and I 
> will give post the URL on this list. Any comments on doing it 
> that way?
> Peter
> -----------------------------------------------------------
> peter59 at sbcglobal.net - http://www.geocities.com/anapro.geo/
> > -----Original Message-----
> > > While searching for a power cord, I "found" a package of
> > some 444-66 ICs
> > > that I had made for my 6MHz H89 modification. These are
> > 
> > Cool!
> > 
> > I'm running one of your 4 MHz mods in my main H89 right now. Out of 
> > curiousity, what else would be required to change it to 6 MHz?
> > --
> > --
> > Lee A. Hart  814 8th Ave N  Sartell MN 56377
> > leeahart_at_earthlink.net
> --
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