Choose your card

The card follows from the backplane, not from preference. Look at the machine you mean to put it in.

Which bus is in the box

Your machine	Bus	Card
PDP-11/04, /05, /34, /35, /40, /44, /45, /55, /70	UNIBUS	UniBone
PDP-10 and VAX expansion backplanes	UNIBUS	UniBone
LSI-11/03, PDP-11/23, /23+, /53, /73, /83, /93	QBUS	QBone
MicroVAX I, II, 3000-series	QBUS	QBone

If you are unsure, count the fingers. A UNIBUS SPC slot takes a card on all four rows A–D; a QBUS card cage carries the bus on rows A and B, with C and D varying by backplane — see Fitting it to a backplane.

Both cards are quad-height, both carry a BeagleBone Black, and both run the same QUniLator software.

Where they differ

Most of this manual applies to either card. These are the differences that reach the operator:

Address width

UNIBUS · UniBone

UNIBUS is fixed at 18 bits — 256 KB of address space. The larger PDP-11s (11/44, 11/70) reach 22 bits only over a separate memory bus, which UniBone does not sit on.

QBUS · QBone

QBUS runs at 16, 18 or 22 bits, multiplexed onto the DAL lines, and the CPU determines which. QBone cannot infer it from bus traffic, so it is configured — and on an LSI-11/03 the DAL<21:18> jumpers must come off, because those backplane lines carry CPU-internal signals there.

Getting this wrong shows up as memory that answers at the wrong addresses, or an I/O page that does not answer at all.

An emulated processor

UNIBUS · UniBone

UniBone can be the CPU. It emulates a KA11 (11/20) and a KD11-EA (11/34 with KT11-D memory management), both validated against the original DEC MAINDEC diagnostics. A backplane with no working processor still becomes a running machine.

QBUS · QBone

QBone ships no emulated processor — it drives a real CPU board in the cage beside it. Everything else QUniLator emulates is available on both cards.

Grant continuity

UNIBUS · UniBone

UniBone doubles as a G727 grant continuity card, with an NPG-closing function. The slot it goes into wants an open NPG chain at CA1–CB1.

QBUS · QBone

QBone’s C/D grant continuity is jumpered, and the correct setting depends on the backplane — an H9270 or H9275 wants the jumpers closed, an H9276 open, an H9278 depends on the slot. Empty QBUS slots between the CPU and the last used slot still need G9047 grant continuity cards.

The line-time clock

QBUS · QBone

QBUS carries EVNT, which DEC power supplies drive with a 50/60 Hz square wave to give the operating system a line-time clock. QBone can generate 50 Hz itself via a jumper, for a machine on a non-DEC supply — but only one source may drive EVNT at a time.

Diagnostic companion

The signal adapter that pairs with the card differs by bus: UniProbe for UNIBUS, QProbe for QBUS. Both are debugging terminators with signal LEDs and logic-analyser connectors.

A note on maturity

QBone runs on real hardware and is regularly exercised. UniBone is currently untested in this codebase — it cross-compiles, CI builds and packages it, and its image comes off the same script, but none of it has been run on a UniBone in a live backplane. The DEUNA Ethernet emulation in particular has never been run against an operating system.

If you have UNIBUS hardware, reports are very welcome — see the project.