16 Jun
2008
16 Jun
'08
7:07 p.m.
On Tue, Jun 17, 2008 at 11:53 AM, bfranchuk at jetnet.ab.ca <
bfranchuk at jetnet.ab.ca> wrote:
Roy J. Tellason wrote:
Should that be mA for load? I am pretty much a noob at EE and design, but I
did manage to get my head around fanout and loading calculations. They feel
funny at first when self teaching yourself and then all of a sudden make
sense.
David
I'm thinking about building a z80 board,
with varying amounts of "stuff"
attached, with RAM and ROM that may be NMOS or CMOS, and some
indeterminate number of Z80-family and compatible peripheral chips.
My question is this: At what point do you _need_ to have address and data
bus buffer chips?
Read the $%#! manual to put it bluntly. A simple guess is once your
design is larger than a small card, you need I/O buffering. I think
a 6800 cpu can drive about 150 pf and a typical load is 10 pf at
rated speeds.