Tony wrote: I have, it's a Biomation K100-D. When I first set it up Sunday afternoon, and turned the LA on, the screen moves vertically. So I had to get the LA in good working order first! As I have the operator & service manual, the location of the vertical freq. adjustment was quickly found. The screen is now steady. I connected the pod B, 8 data inputs to the ROM address lines A0-A7, and gave it a manual trigger to capture all it sees. At first I got too much detail (address repeats several times), but after setting the clock of the LA to sample at 10 ?s I got almost always consecutive addresses. That depends on the length of the instruction. Anyway, I see the addresses 60-110 (octal) in the correct order and see the address jump at 101 to the address 335 (a subroutine). I see the complete execution of the subroutine and the return. Indeed going to address 105. That means the stackpointer and the memory must be OK! ReturnPC stored in RAM, and retrieved correctly. However, I can not check everything. Need to connect pod A, and have 8 more data input lines to measure interesting things. And trigger facilities! It's time to read the user manual of the LA, to do advanced measurements. I still haven't got a clue what's going wrong ... - Henk. This message and attachment(s) are intended solely for the use of the addressee and may contain information that is privileged, confidential or otherwise exempt from disclosure under applicable law. If you are not the intended recipient or agent thereof responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by telephone and with a "reply" message. Thank you for your cooperation.