I am using a 89C450MCL mcu running at 29.492mhz
With just the micro, 74F573 (or 74HCT573 tried both) and a IS62C1024-35
RAM
chip it seems I loose the address sometimes at the output of the latch
when
/WR goes low.
I am using plenty of bypas caps and 4.6uf caps for supply lines.
I am simply trying to clear a memory range from 0000h - 00FFh.
I put my logic probe on the address lines of the RAM chip after the latch
and I can see the address sometimes going wrong.
See http://www.eddie1.net/timing.jpg
for reference.
As you can see I am just writing to memory and as the image shows 1Ch is
fine 1Dh is fine but 1Eh and 1Fh are dropping the address then 20h is fine
and 21h is fine.
This is not the only place it goes wrong and I cannot find any corelation
in
the locations that go wrong.
Any ideas??
