Hi

Setting:
I am using the keil microvision compiler. The hardware is an selfmade DS80C320 experimentation board put together on an breadboard. The whole uses 11.0592Mhz crystal. The bus has an M27C64 ROM, UM512 SRAM and an 8255 wired as an IDE controller.

Problem:
When loading a program on the processor using mon51 i get errors like "MONITOR ERROR 22: NO CODE MEMORY AT ADDRESS 44BDH". (these adresses vary a bit but only bit 1 and 0)

I have done many things to solve this problem (i do not have a big EE background i am just learning electronics by myself, please take that in account). When changing the latch from an TI SN74F573 to an 74HCT573N the problem has gone away completely. I have read the FAQ on noise problems and followed all the tips and recommendations to the letter (i have also put caps on every rail of the breadboard)

Well with the latch change it all works fine, but why? I have used more or less F type TTL chips everywhere, should i use HCT? Or should i be glad that it just works on the breadboard design? The supplies seem okay when i check my scope but i am using an ordinary computer power supply as power source.