Get a scope !!!!

Is the design o.k ?

Step 0: check power supply and leads/traces for shorts.
Step 1: does the crystal work ?
Step 2: Is the ALE signal there ?
Step 3: is the PSEN signal there ?

Load some code that repeatedly reads
and writes 0xAA 0x55 to adresses 0xAA55
0x55AA. Check adress and data lines for shorts.


Is the RAM/EPROM fast enough ?

How about the 373/573 latch ?

See Dallas semiconductor's hi-speed micro appnotes. They have some useful tips.
Also check Jack Ganssles pages.(www.ganssle.com)

Good luck
Jan