UniProbe - M9302 functionality

Parent Category: Tools Category: UniProbe - an UNIBUS signal adapter Written by Administrator

When build for Standard UNIBUS, UniProbe is plugged into the backplane "end" sockets and must act as bus terminator. It is identical to a regular M9302 terminator card then.

m9302

 With inline resistor packs we can build it smaller:

uniprobe3d m9302

There are some differences to the original M9302:

  •  the voltage dividers are not 178 / 383 ohm, but 180 / 390 ... the ratio error is 1%.
  •  the source voltage for the terminators can be separated from +5V.
    By varying the terminator voltage, "Margin Testing" on the bus can be performed, as described by DEC.
  •  the M9302 terminator has "SACK turnaround logic."
    This function answers any BUS GRANT with a proper SACK, if a GRANT is ignored by all device cards.
    Here it can be disabled by a jumper, converting UniProbe back into an older M930 terminator.

sack turnaround