Further PDP-11/05 debugging -- core memory faults

On Sat, Sep 6, 2014 at 12:53 AM, Brent Hilpert <hilpert at cs.ubc.ca> wrote: Towards the end you state "They don't get smaller than that required by a simple calculator, ....". However there was a very common device made from the mid '50s to mid 70s that used a 10 x 10 array of cores; the Jukebox. Seeburg was a major Jukebox vendor of the era. It used the "Tormat" selection system. Basically the average Jukebox had 50 records or 100 selections (a record having two sides). One core was used per selection. The cores were set using basic 2D selection but no decoders were needed. Rather the front of the unit had 10 letter keys (A-H) and 10 number keys (1-10). After coughing up a dime the user pressed a letter and a number to select a record then a core was selected via the 10 row and 10 column select lines. Reading back was done when the unit was searching for its' next record. Each core had a private winding that had one side grounded and the other connected to a pin. As the unit scanned each pin was mechanically contacted and the core was pulsed. A common sense line went through all 100 cores. If the sense line detected a flip a solenoid was fired that caused the record unit to stop moving left to right (or right to left) and grab a record and play it. The cores used were huge. Here's a picture http://members.home.nl/schniermanni/seeburg/matrix.jpg . Marc