Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!stout!cook
From: cook@stout.ucar.edu (Forrest Cook)
Newsgroups: sci.electronics
Subject: Re: S-100 update
Message-ID: <1407@ncar.ucar.edu>
Date: 14 Feb 89 18:08:05 GMT
References: <885@csd4.milw.wisc.edu>
Sender: news@ncar.ucar.edu
Reply-To: cook@stout.UCAR.EDU (Forrest Cook)
Distribution: all
Organization: Field Observing Facility, NCAR, Boulder, CO
Lines: 32

In article <885@csd4.milw.wisc.edu> paravia@csd4.milw.wisc.edu (Mark David Kakatsch) writes:
>   About my S-100 system, It SEEMS to be working, but I am not sure. It's 
>generating the signals that it is supposed to, however, they aren't exactly 
>square waves. It's more of a sine/triangle wave.
...
>is with an Imsai type front panel.

AAACK PHTHTHT		You said that word, IMSAI!

I have an old Imsai and the reason your bus has non-square waves is probably
due to the fact that the front panel's LEDs are connected directly to the
bus with NO buffering.  Who did that anyway?  If you want to make the thing
work much more reliably,  kludge in some octal buffer chips between the
bus and the LEDs.  While you are at it, it might not hurt to cut the power
switch traces that run about 1/4" from a bunch of one-shots and run the AC
right to the switch.  220/330 ohm terminator resistors on all of the bus
lines will also clean up the signals.
Remember the front panel will only work with CPU cards that have the CPU
data bus availible on a 16 pin socket, and port FF is used by the front
panel data in/out port so beware of address conflicts.

Remember, you can buy a NEW 10Mhz XT clone with 640K and 30Mb of hard
disk for $1200 if you shop around.  There is a public domain? program
called Z80MU that will allow you to run your old CP/M software if you
must.  I use that setup on a 386 to cross compile Aztek C for Z-80 boxes.
The 20 Mhz 386 can emulate a 2.1 Mhz Z-80, WOW :-)


 ^	Forrest Cook   (The preceding comments were my Opinions)	 ^
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