Date   : Mon, 11 Mar 1985 18:38:44 cst
From   : "riggs, austen" <garey@UT-NGP.ARPA>
Subject: re: z80A/z80B pinouts

You can replace the chips with each other.  I went from a 2.5 MHz z80 to a
Z80B that I run at 5 MHz on my Kaypro.  To use the higher clock rate the
B chip is capable of you need to change the clock signal.  On the Kaypro
there are 4 and 5 MHz signals available so a simple jumper is all thats
required.  However I have a Z80H (8 MHz) on order.  From what I gather, I'll
need to either change crystals or add a circuit to divide off an 8 MHz
signal from somewhere.

The hitch is that the computer is designed for one speed.  I've also had to
reburn the two eproms in my machine on faster parts.  other possibilitys of
problems are the speed of the ram chips.  Some people have had to also upgrade
their SIO's and PIO's to the "B" rating, but mine have been fine.

I bet if there is a user's group for whatever computer you have, someone there
has done it and can help you.

               Good Luck     Jim Garey    garey@ut-ngp.arpa