Date   : Mon, 23 Sep 1991 04:33:00 GMT
From   : psgrain!percy!nosun!techbook!fzsitvay@uunet.uu.net (Frank Zsitvay)
Subject: Re: Qterm/vt100

In article <XX00012d11@pallio.UUCP> dg@pallio.UUCP (David Goodenough) writes:
>fzsitvay@techbook.COM sez:
>>  but if you can't find one, i'll help you with it.  I have a kaypro II 83,
>> .....
>
>Humm. You wanna be a beta tester for the driver when I get it done?

  sure - just toss source in so i can see what you're doing.  
 
  another possibility that works, albeit a hardware solution, is to pull
the Z80 from its socket, bend pin 24 up, reinsert the chip with pin 24
still sticking up, and solder one leg of a 220 ohm resistor to pin
24.  solder a wire onto the other leg, and run it to a +5 source in the
computer. (pin 11 on the Z80 will do.)
 
  stick one end of a 220-1000 ohm resistor into pin 24 of the Z80s
socket (making sure it does not touch pin 24 of the Z80) and tie
the other end to Z80 pin 29.
 
  what this does is eliminate the WAIT state that was built into the
kaypro.  i haven't tried this on a kaypro, only on a TRS80 model II,
and had good success getting it to keep up at 2400 baud.
 
  bear in mind, this mod is not guarenteed (only do this if you've done
stuff like this before).   don't hold me responsible if you blow up your
machine.

  a little clarification - i'm not even sure if there was a wait state
or two added to the kaypro machine cycle, however i do remember this
was a common practice way back when, and it mainly was because of the
memory chips being used.  most were conservatively rated, and most
machines will work with the wait state removed.  this mod speeds up a
TRS80 Mod II about 20-25%.
 
  some boot roms are too slow to operate without the wait state, and some
disk format programs use CPU timing cycles as part of their operation,
so this will not work on those machines.
 
  if you do this mod, the first thing you should try when you complete
the hardware side of it is to boot the machine and try to format a
disk.  if everything still works right, then i'd say it's safe...
 
  and even if it does not work, it's easy to undo...


-- 
fzsitvay@techbook.COM - but don't quote me on that....

  According to a reputable source, 'glastnost' translated from Russian
really means 'lesser grade of barbed wire.'