QProbe - QBUS Interface

Parent Category: Tools Category: QProbe - a QBUS signal adapter Written by Administrator

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QProbes QBUS itnerface consists of

  • labled FlipChip fingers
  • optional termination resistor packs
  • optional separate voltage for resistor packs for QBUS margin testing.
  • pinheaders to access every QBUS signal via Multimeter, oscilloskope or Logic analyzer

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Bus terminators

Resistor pakca can be plugged unto QBUS signal wires to terminate the BUs with 120 or 240 Ohm.

On typical single-backplane systems, termination is not required at all.

When using the bus terminators, plug QProbe behind the last occupied QBUS slot.

The DEC part for sole bus termination is a mostly unpopulated variant of M9400, REV11-E.

Dive into DECs alchemic rules for terminaton resistor values yourself!


LSI11/03 M7264 and M7220

The old 16 bit LIS11/03 CPUs make special use of QBUS signals pins BC1, BD1, BE1 and BF1. On later CPUs this pins are used (or reserved) for 22 bit address extension via BDAL<21:18>.

On the early LSI11/03s, thes wires transport CPU internal state information, and they are badly buffered. So terminator resistors here may disturb CPU operation.