VMS on an emulated VAX-11/780

Verified on real hardware

QUniLator 1.16.0-1, 2026-08-06, on a UniBone with no backplane — the card on a bench, driving its own internal bus. VMS V4.7 booted from the emulated UDA50 to a login prompt.

What you will have at the end

VAX/VMS V4.7, booted from a disk that is a file, on a processor that is software, on a bus with nothing else on it — running on a BeagleBone with a UniBone cape and no PDP-11 in sight.

The other walkthroughs put QUniLator into a machine. This one is the machine.

The machine

Processor	Emulated VAX-11/780 (cpuvax), 4 MB
Backplane	None. The card runs on its internal bus — no cage, no cards, no terminator
From QUniLator	Everything: processor, memory, a UDA50 with one drive, a DEUNA, a DZV11

This is the configuration to reach for when you have a card but no machine yet — it exercises the whole emulation stack and needs nothing but power and a network cable.

UNIBUS · UniBone

An emulated processor is UNIBUS-only. A QBone drives a real CPU board beside it and ships no processor emulation, so this walkthrough has no QBUS equivalent.

What you need

• A UniBone with QUniLator on it. It need not be in a backplane.
• A VMS system disk image — vms47.dsk here, about 147 MB.
• Nothing else. There is no console cable: the emulated VAX has its own console, and the browser is the terminal.

1. Tell the card it has no bus

On Machine, the card must be running on its internal bus — the emulated processor and the emulated devices talk to each other inside the software, and nothing is driven onto the physical connector.

Set External console to Off. The VAX’s console is its own, not a serial line on the cape.

2. Build the machine

On Configurations, five devices:

Device	Setting
cpuvax	the VAX-11/780 processor, memory = 4 (MB)
uda	the UDA50 MSCP controller
uda0	the system disk, holding vms47.dsk
deuna	Ethernet, on interface veth-pdp
dzv11	a serial mux, for terminals beyond the console

The saved configuration on this card is called vax.

3. Switch it on

Press AUX ON/OFF. The console to watch is the VAX’s own — the console widget on the dashboard shows it.

VMS boots straight through and stops to ask the time:

   VAX/VMS Version V4.7 28-Oct-1987 13:00

PLEASE ENTER DATE AND TIME (DD-MMM-YYYY  HH:MM)

It always asks, every boot

There is no battery-backed clock behind an emulated processor, so VMS has nothing to read the time from and asks. Answer in exactly the format shown — 06-AUG-2026 08:00. A malformed answer is asked again.

Startup then runs to completion:

%%%%%%%%%%%  OPCOM   6-AUG-2026 08:01:14.40  %%%%%%%%%%%
Logfile has been initialized by operator _OPA0:
Logfile is SYS$SYSROOT:[SYSMGR]OPERATOR.LOG;23

%SET-I-INTSET, login interactive limit = 64, current interactive value = 0
  SYSTEM       job terminated at  6-AUG-2026 08:01:17.07

SYSTEM job terminated is the startup batch job finishing normally, not an error. Press Return and you have a login:

Username:

The system disk here carries the traditional SYSTEM account.

What can go wrong

Nothing on the console at all	The console widget is showing the wrong line. An emulated VAX talks on its own console channel, not on ttyS2; check External console is Off.
The date prompt returns immediately	The format is exact: two-digit day, three-letter month, four-digit year, two spaces before the time is not required but the dashes are.
It boots about half the time	Fixed. An interrupt granted with a zero vector at batch entry used to wedge the boot; if you see it, you are on a build older than the fix.
The card is in a backplane and behaves oddly	An emulated processor takes the bus over. Do not leave a real CPU in the cage with it.

Where this one goes next

This configuration is the project’s own proving ground for the UNIBUS side, and the emulated processors are validated against DEC’s original MAINDEC diagnostics on every build. What has not been exercised much is a UniBone in a live, terminated backplane driving real cards — if you have UNIBUS hardware, that is the report the project most wants.