PDP-9 lives again....

Some 20 odd years after it was decommisioned we finally got our PDP-9 to boot software off an old DECTape. Advanced Software System version 5A came up today for the first time on our restored -9. This after a long and frustrating summer when we spent over 100 man hours chasing a processor fault which resulted in the execution of the saved PC value after an interrupt (instead of the word after the saved PC value). Turned out to be a misaligned delay circuit which caused a reset signal to arrive late and provoke all sorts of havoc in the processor while nicely reseting all the tell-tales. Seems like the memory and processor hardware is quite stable now. We have two DECtape units attached with two more units availabe to be attached. Further debug on the DECtapes and learning the software will be followed by attachemnt of TU20 mag tape units. If anyone knows of an available (and cheap) large X-Y plotting scope preferably somewhere in europe we would be very interested in hearing from you. We have a graphics controller but no large screen. With the screen, the DECtapes and the TU20's this is going to be one impressive system. We also used the -9 for the first time today to try and recover an image from an old Elliott 903 paper tape I was given in the UK recently. Due to operator error that attempt failed but I fully expect to be able to get a tape image this weekend. -- hbp