I'm not making a lot of progress, was using my time to fix the Citroen DS replacing thegearbox in it and overhauling the steering cylinder and fixing a lot of little items which you encounter when working on a 44 year old car. It's a little like classic computing, if you don't touch it everything keeps working, but if ....etc. Citroen used a rubber based wire insulation for the DS and Pallas models between 1965 and 1968. This kind of insulation hardens over time and corrodes the copper wires, in the Safari I have, this wiring isn't used for the main wiring harness (lucky me:-) but they used it for smaller components like the wiper engine wiring and ignition resistor wiring etc.. Real fun and lots of fuses ;-) To come back to the HP 9830 I did find some time to connect the LA to the datapath board and look at the Carry and ALU signals The carry doesn't change while the processor is running it's test cycle, the QC and AC lines seems to be consistent to the processor state. So I think I have to look at the timing of U12B and at the BCD mode X2. I'll get it running .. some day -Rik is fix the