Need Help Identifying Symbols

[Rerouter]

I'm in the process of making some old schematics more readable, but i want to be careful that i am not going to scrub something important,
the schematics in question are riddled with "signatures" values that where used way back in the 80's for diagnosing hardware,

these 2 keep on popping up, and while i believe the crossed zero is to differentiate from a O the tailed P i cant find info on,
http://desmond.imageshack.us/Himg254/scaled.php?server=254&filename=symbols.jpg&res=crop

would anyone have any idea on what these 2 refer to?

[Kremmen]

Seeing the symbols used in context could help a lot. Can you provide a picture of some text where they appear?

[Rerouter]

here you are, but be warned, its a 1MB gif
http://desmond.imageshack.us/Himg191/scaled.php?server=191&filename=data600001212.gif&res=landing

on the same subject, any idea what the signatures might decode to? (bolded 4 letter values)

[free_electron]

Looks like an old hp design. 70000 series main computer board ?

The signatures are used for debugging the system. You need a model 5004 5005 or 5006 signature multimeter to do this.
This si a machine that you connect to three points on the board. Typically a trigger point, a clock point and a start stop signal.
The system that needs testing is put in a special mode. They let the cpu cycle NOP operations.

The testprobe is then poked at various points. The signature multimeter looks at the pattern flying by and they record 16 samples that are then decoded to a hex number.

If there is any problem in the system the pattern will change. So thats how you troubleshoot these things.

A very helpful piece of equipment. I have one and it has helped me raise at least 4 machines from the dead...

[Kremmen]

Yes it is old for sure. HP, DEC, Data General... maybe HP. Those symbols have nothing directly to do with the signals they are next to. My bet is some kind of debugging notation.