Re: ZipGSx Upgrade Questions (I've read the FAQ's)

[marvinmiller@hotmail.com (Marvin Miller)]

Hi Scott;

You might want to check this out for more 'old info' on cache speed as
well as the 74F00 chip mod. I don't know if it will help, but I found
it pretty comprehensive.

http://ground.ecn.uiowa.edu/apple2/MiscInfo/ZipGS/zipgs.ramspeed

Best;
Marvin



On Sun, 12 Nov 2000 21:43:53 -0000,
salfter@salfter.ncc74656.dyndns.org (Scott Alfter) wrote:

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>In article <3A0DDF69.9C697C9D@swbell.net>,
>Rubywand  <rubywand@swbell.net> wrote:
>>> ** Replacing the 74F00 chip with the 74HC00 one **
>>
>>     Where did you find this in the FAQs?
>
>I can't speak for the original poster, but I recall reading this in one of
>the accelerator-upgrade FAQs.
>
>>     Do not know why anyone would replace a 74F00 with a 74HC00 on an
>>accelerator board. The 74F00 is a much faster gate than the 74HC00. You would
>>think that when speeding up a board you would, if anything, want to move to
>>faster gates. Suggest you leave your 74F00 where it is until whoever made the
>>recommendation explains it.
>
>This could explain why my computer has been a bit unstable since I modded my
>ZipGS (14-MHz processor underclocked @ 12.5 MHz (who sells 56-MHz
>oscillators?) increased from 7 MHz, 64K cache increased from 16K).  Even
>sticking an extra power connector on (a connector like you'd find on a hard
>drive, drawing from a 250W power supply I hacked into the computer) hasn't
>provided a substantial improvement.  Adding a few decoupling capacitors in
>selected locations (.1 uF across +5 and GND on each cache chip and 10-100 uF
>electrolytics in some places provided for them along the bottom) didn't have
>much of an effect.  Mainly, the system crashes while in GS/OS...ProDOS 8
>seems more stable.  The computer also has a rev. C RamFAST, a SoundMeister,
>and a RAM-GS 4-meg memory expansion installed.
>
>Time to dig up the 74F00 I pulled out and see if putting it back in will
>make an improvement...
>
>(I thought it was in the comp.sys.apple2 FAQ, but it wasn't.  It also wasn't
>in the HyperCard stack mentioned in the section on accelerators.  Digging
>into some archived mail, I received some advice there that the 74F00 ought
>to be replaced with a 74HCT00 (which is what's on mine).  IIRC, the only
>difference between HC and HCT parts is that HCT parts can be mixed with TTL
>(the "T" is for "TTL-compatible").  Are HC parts that much slower than F
>parts?  I could look it up, but I'm a bit lazy right now. :-) )
>
>  _/_
> / v \
>(IIGS(  Scott Alfter (remove Voyager's hull number for email address)
> \_^_/  http://salfter.dyndns.org
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