The Laser 128EX I have had a GTE Microelectronics 65c02 installed before I put in a WDC 65802. Both are 4 Mhz cpus. Both work for me. I did have a problem with Laser's 5.0 ROM but not with its 4.5 ROM. The 65802 works fine in emulation and native mode. Andy Werner st2975@siucvmb.siu.edu