Tony wrote: Making your own pod...! Again, points earned Tony! Chapeau! :-) Jim already told me that the 8008 uses an internal stack, but I am now not so sure that the RAM is OK, so I will connect the other 8 LA probes to the databus, to see what is taken out of the RAM to put on the displays. Yesterday evening was short. Much to do ... but I managed to look at the matrix signals. It sort-of looks OK, but I admit that I must make some better measurements to be 100% sure that it is not there where my problem lies. The outputs of the 8881's (on page 4, KY11-LB console board) look as described before, and that is also what I see on the inputs of the 8093 (page KY-3). But taking samples on the outputs is more work, as that is the databus (input). So I see a lot of pulses are on those lines, and it needs more setup work to find out if a stuck bit is messing things up. It is not likely a problem of a stuck bit on the address or data bus, because that would corrupt the program execution of the ROM code. I still have the feeling that there is no problem with the RAM, ROM, CPU, 3-state transceiver, and the decoding logic. This evening I hope to check out (thoroughly) the keypad circuits. thanks for the input! - 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.