The undefined memory address is a normal warning that everyone will get.

Undefinded memory. -- asdfasdf
Posted by egm , May 03,1999,07:25 Post Reply  Forum

At 0ns, everything is undefined and the memory makes note of that. This is only a warning and does not hinder the EPROM from working correctly. You need to be sure to pulse the LD line to initialize memory. Then, when you have a valid address in the A[7:0] input port, memory Q[7:0] will update 30ns after you assert the address. Be sure that you are asserting a valid address and be sure that you gave a pulse on the LD line.