From Newsgroup: comp.os.vms

Hello,
I am installing OpenVMS VAX 5.5-2H4 under SIMH and am confused by how standalone BACKUP assigns device names when booted from installation media. This is where I got the ISO from (Server 1) [https://winworldpc.com/download/b0d47071-ccb7-11e7-a73f-fa163e9022f0](https://winworldpc.com/download/b0d47071-ccb7-11e7-a73f-fa163e9022f0)
Setup (simplified):
- SIMH VAX (have tried MicroVAX 3900 and VAX 8600)
- OpenVMS VAX 5.5-2H4 ISO attached as an RQ device (read-only)
- Booting directly from the ISO into standalone BACKUP
In standalone BACKUP, the installation media always appears as DJAx
(device type RA60), not as DUAx, for example:
Available device DJA3: device type RA60
As a result, restoring the saveset only works using:
BACKUP DJA3:VMS2H4055.B/SAVE_SET DUA0:
However, I have seen multiple reports (e.g. WinWorldPC forum, blog tutorials) where users claim to restore from the *same* OpenVMS 5.5-2H4 ISO using:
BACKUP DUAx:VMS2H4055.B/SAVE_SET DUA0:
Example tutorials where ISO image can be access as a logical device (DUAx) rather than as a physical device (DJAx):
[https://forum.winworldpc.com/discussion/11935/vms-5-x](https://forum.winworldpc.com/discussion/11935/vms-5-x)
[https://hb1bbs.com/VAX/VMS-on-a-Raspberry-Pi/](https://hb1bbs.com/VAX/VMS-on-a-Raspberry-Pi/)
[https://www.openvmshobby.com/vax-vms/openvms-on-vax-simh/](https://www.openvmshobby.com/vax-vms/openvms-on-vax-simh/)
[https://www.wherry.com/gadgets/retrocomputing/vax-simh.html](https://www.wherry.com/gadgets/retrocomputing/vax-simh.html)
My questions are:
1) Under standalone BACKUP 5.5-2H4, what determines whether the boot
device is assigned DUAx vs DJAx?
2) Is this affected by the VAX model (MicroVAX vs 8600/8650), SIMH MSCP configuration, or whether BACKUP was booted from that device?
3) Is DJAx actually the expected and correct name for RA60-based ISO
media in this environment?
4) Using my setup is it at all possible for me to restore the save_set with a command such as:
$ backup dua3:VMS2H4055.b/save_set dua0:
instead of
$ backup dja3:VMS2H4055.b/save_set dua0:
Any clarification would be greatly appreciated.
Thank you,
Sean
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From Newsgroup: comp.os.vms

Hello,

I am installing OpenVMS VAX 5.5-2H4 under SIMH 4.0 on a Raspberry Pi 3B+ running Raspi OS "Trixie".
I am confused by how standalone BACKUP assigns device names when booted from installation media.

This is where I got the ISO from (Server 1)-a-a [[https://winworldpc.com/download/b0d47071-ccb7-11e7-a73f-fa163e9022f0](https://winworldpc.com/download/b0d47071-ccb7-11e7-a73f-fa163e9022f0)](https://winworldpc.com/download/b0d47071-ccb7-11e7-a73f-fa163e9022f0](https://winworldpc.com/download/b0d47071-ccb7-11e7-a73f-fa163e9022f0))

Setup (simplified):-a-a
- SIMH VAX (have tried MicroVAX 3900 and VAX 8600)-a-a
- OpenVMS VAX 5.5-2H4 ISO attached as an RQ device (read-only)-a-a
- Booting directly from the ISO into standalone BACKUP

In standalone BACKUP, the installation media always appears as DJAx-a-a (device type RA60), not as DUAx, for example:

Available device DJA3: device type RA60

As a result, restoring the saveset only works using:

BACKUP DJA3:VMS2H4055.B/SAVE_SET DUA0:

However, I have seen multiple reports (e.g. WinWorldPC forum, blog tutorials)-a-a
where users claim to restore from the *same* OpenVMS 5.5-2H4 ISO using:

BACKUP DUAx:VMS2H4055.B/SAVE_SET DUA0:

Example tutorials where ISO image can be access as a logical device (DUAx) rather than as a physical device (DJAx):-a-a
[[https://forum.winworldpc.com/discussion/11935/vms-5-x](https://forum.winworldpc.com/discussion/11935/vms-5-x)](https://forum.winworldpc.com/discussion/11935/vms-5-x](https://forum.winworldpc.com/discussion/11935/vms-5-x))-a-a
[[https://hb1bbs.com/VAX/VMS-on-a-Raspberry-Pi/](https://hb1bbs.com/VAX/VMS-on-a-Raspberry-Pi/)](https://hb1bbs.com/VAX/VMS-on-a-Raspberry-Pi/](https://hb1bbs.com/VAX/VMS-on-a-Raspberry-Pi/))-a-a
[[https://www.openvmshobby.com/vax-vms/openvms-on-vax-simh/](https://www.openvmshobby.com/vax-vms/openvms-on-vax-simh/)](https://www.openvmshobby.com/vax-vms/openvms-on-vax-simh/](https://www.openvmshobby.com/vax-vms/openvms-on-vax-simh/))-a-a
[[https://www.wherry.com/gadgets/retrocomputing/vax-simh.html](https://www.wherry.com/gadgets/retrocomputing/vax-simh.html)](https://www.wherry.com/gadgets/retrocomputing/vax-simh.html](https://www.wherry.com/gadgets/retrocomputing/vax-simh.html))

My questions are:

1) Under standalone BACKUP 5.5-2H4, what determines whether the boot-a-a device is assigned DUAx vs DJAx?-a-a
2) Is this affected by the VAX model (MicroVAX vs 8600/8650), SIMH MSCP-a-a configuration, or whether BACKUP was booted from that device?-a-a
3) Is DJAx actually the expected and correct name for RA60-based ISO-a-a media in this environment?-a-a
4) Using my setup is it at all possible for me to restore the save_set with a command such as:-a-a
$ backup dua3:VMS2H4055.b/save_set dua0:-a-a
instead of-a-a
$ backup dja3:VMS2H4055.b/save_set dua0:

Any clarification would be greatly appreciated.

Thank you,-a-a
Sean
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From Newsgroup: comp.os.vms

On 12/17/2025 5:52 PM, flexmcmurphy wrote:

Setup (simplified):
- SIMH VAX (have tried MicroVAX 3900 and VAX 8600)
- OpenVMS VAX 5.5-2H4 ISO attached as an RQ device (read-only)
- Booting directly from the ISO into standalone BACKUP

In standalone BACKUP, the installation media always appears as DJAx
(device type RA60), not as DUAx, for example:

Available device DJA3: device type RA60

As a result, restoring the saveset only works using:

BACKUP DJA3:VMS2H4055.B/SAVE_SET DUA0:

However, I have seen multiple reports (e.g. WinWorldPC forum, blog tutorials) where users claim to restore from the *same* OpenVMS 5.5-2H4 ISO using:

BACKUP DUAx:VMS2H4055.B/SAVE_SET DUA0:

1) Under standalone BACKUP 5.5-2H4, what determines whether the boot
device is assigned DUAx vs DJAx?
2) Is this affected by the VAX model (MicroVAX vs 8600/8650), SIMH MSCP configuration, or whether BACKUP was booted from that device?
3) Is DJAx actually the expected and correct name for RA60-based ISO
media in this environment?
4) Using my setup is it at all possible for me to restore the save_set with a command such as:
$ backup dua3:VMS2H4055.b/save_set dua0:
instead of
$ backup dja3:VMS2H4055.b/save_set dua0:

Any clarification would be greatly appreciated.

Traditional VMS disk device naming is:

D = disk
X = controller type, U=Unibus, I=DSSI, K=SCSI
Y = controller number, A=first, B=second, C=third ...
N = unit on controller, either 0=first, 1=second, 2=third ... or
0=first, 100=second, 200=third

RA81's and RA82's become DU disks.

Google indicate that RA60's become DJ disk. Not sure why. I am not old
enough to know RA60's. Maybe someone else can elaborate on why RA60's
are DJ and not DU.

Arne

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.os.vms

On 12/17/2025 6:53 PM, Arne Vajh|+j wrote:

Traditional VMS disk device naming is:

D = disk
X = controller type, U=Unibus, I=DSSI, K=SCSI
Y = controller number, A=first, B=second, C=third ...
N = unit on controller, either 0=first, 1=second, 2=third ... or 0=first, 100=second, 200=third

RA81's and RA82's become DU disks.

Google indicate that RA60's become DJ disk. Not sure why. I am not old
enough to know RA60's. Maybe someone else can elaborate on why RA60's
are DJ and not DU.

Arne

Because they were removable pack disks. I guess DEC decided to make them notable for that and different from the fixed disk DU.
--
John H. Reinhardt

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.os.vms

On Wed, 17 Dec 2025 19:08:24 -0600, John H. Reinhardt wrote:

On 12/17/2025 6:53 PM, Arne Vajh|+j wrote:

Google indicate that RA60's become DJ disk. Not sure why. I am not
old enough to know RA60's. Maybe someone else can elaborate on why
RA60's are DJ and not DU.

Because they were removable pack disks.

I never understood the DEC disk naming scheme. Which were DJ and which
were DK? Which ones were rCLremovablerCY disks, and which ones were rCLcartridgerCY disks? Why did DX floppy drives become DY just because of
the double density or double sides (I forget which now)? How did they
pick letters for DM, DR, DU drives etc? DidnrCOt all the model numbers
begin with R, anyway?

Lawrence
still trying to figure out why some USB-serial devices appear on Linux
as ttyUSB, and others as ttyACM
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.os.vms

flexmcmurphy <plica2006@gmail.com> writes:

In standalone BACKUP, the installation media always appears as DJAx
(device type RA60), not as DUAx, for example:

What you get depends on your controller, disk type, and unit you attach (basically the machine you create in your SIMH .ini file).

https://wiki.vmssoftware.com/Device_Name

So DJ is a RA60 Disk.

As a result, restoring the saveset only works using:

BACKUP DJA3:VMS2H4055.B/SAVE_SET DUA0:

As long as you install it and it works, it doesn't matter.

1) Under standalone BACKUP 5.5-2H4, what determines whether the boot
device is assigned DUAx vs DJAx?

Your .ini file for SIMH (how you configured your VAX).

2) Is this affected by the VAX model (MicroVAX vs 8600/8650), SIMH MSCP configuration, or whether BACKUP was booted from that device?

Different models allow different hardware, so yes.

3) Is DJAx actually the expected and correct name for RA60-based ISO
media in this environment?

If you're using that disk type, yes. But why use that disk type? There's larger.

4) Using my setup is it at all possible for me to restore the save_set
with a command such as:
$ backup dua3:VMS2H4055.b/save_set dua0:
instead of
$ backup dja3:VMS2H4055.b/save_set dua0:

Those ISO (actually Files-11 On-Disk Structures ODS-2) should attach to
'cdrom' if I recall.

Here's the microvax3900, all set up.

; OpenVMS on VAX setup
;
set cpu 512M
set cpu idle
set cpu conhalt

; Non-volitile memory file goes here
att nvr nvr.bin

; Enable disk drives
set rq0 ena
set rq1 ena
set rq2 ena
set rq3 ena

; We need a second controller since disks go 0-3, only
; 4 per controller. This is controller #2
set rqb ena

; Disk type RA92 is largest VAX supported disk (1.5g)
set rq0 ra92
set rq1 ra92
set rq2 ra92
set rq3 ra92

; This is on the second controller
set rqb0 cdrom


; Attach defined drives to local files
attach rq0 disk0.ra92
attach rq1 disk1.ra92
attach rq2 disk2.ra92
attach rq3 disk3.ra92

; Attach the install CD to its file (read-only)
;attach -r rqb04 VMS_552h4_VAX.iso

; VH lines instead of DZ
set vh dhu
set vh ena
set vh hangup
set vh lines=8
attach -uv VH 127.0.0.1:8888,SPEED=*2

; TK50 cartridge tape drives (MUA0:)
set tq0 ena
set tq1 dis
set tq2 dis
set tq3 dis

; For a printer. Send to a file
set lpt ena
attach lpt printer.txt

; RL11/RL01/RL02 Cartridge Disk (RL)
set rl ena

; Magnetic tape drive (MSA0:)
set ts ena

; Set mac address for 1.10 decnet node.
; AA:00:04:00:0C:04 = 1.12 This must be set
; before interface is upped. DET XQ to detach.
set xq MAC=AA:00:04:00:0C:04
set xq TYPE=DELQA
attach xq tap:tap2

; Start simulator
boot cpu

; DUA3 to boot CD-ROM, DUA0 to boot off disk.
; >>>set boot dua0 in VMS to set default boot disk
;BOOT DUA0

; EOF

Originally, the .iso was on another controller, but since setup another
disk was needed for swap/pagefile so the cdrom had to move to another controller.

If you have graphics, the microvax3900 is a good choice because you can
enable the GUI. It also has alot of attachments. The other good one with
alot of devices/attachments is vax8600.

; VAX8650
; ----------------------------------------------------------------
set cpu model=8650
set cpu 512M
set cpu conhalt
set cpu idle

; Keep time-of-day clock in a file
att todr clock.bin

; Enable a disk, set its type, and attach to file
set rq0 ena
set rq1 ena
set rq2 ena
set rq3 ena

; Disk type RA92 is largest VAX supported disk (1.5g)
set rq0 ra92
set rq1 ra92
set rq2 ra92
set rq3 cdrom

; Attach defined drives to local files
att rq0 disk0.ra92
att rq1 disk1.ra92
att rq2 disk2.ra92

; This is for the CD-ROM image, as during installation
;attach rq3 -r /srv/ftp/pub/operating-systems/vms/disk.iso

; VH serial lines using Linux virtual serial ports (tty0tty0 project).
; These come in pairs and work like a cable. Due to agetty keeping
; tnt0, there are two pairs of lines: one for Linux -> VMS and
; one for VMS -> Linux
;
; Linux (agetty) listens via /dev/tnt0, VMS (simh) grabs /dev/tnt1.
; This is for VMS to dial into Linux.
; Linux can dial in via /dev/tnt2, into VMS /dev/tnt3.
; DECUS UUCP uses TXA0 to call *into* Linux.
; Taylor UUCP (from Linux) calls *out* and connects to TXA1
; Non-UUCP logins work as well, providing they are on the correct port.
set vh dhu,enable
att vh line=0,connect=/dev/tnt1
att vh line=1,connect=/dev/tnt3

; Enable tape drives
set tq0 ena
set tq1 ena
set tq2 dis
set tq3 dis

; A line printer, that goes to a host system file
set lpt ena
att lpt printer.txt

; RP mass-bus
set rp dis

; RL11/RL01/RL02 cartridge disk
set rl dis

; Mag tape drive
set ts ena

; Ethernet network adapter (XU)
set XU ena

; MAC for node 1.11. SCSSYSTEMID number is 1(area) + (1024+node number)
; so 1035
set XU MAC=AA:00:04:00:0B:04
set XU TYPE=DELUA
att XU tap:tap1

; vax8650 needs "boot rq0" to boot, not "boot cpu"
boot rq0

; EOF

The VH lines are black magic to get DECUS UUCP v2 speaking UUCP with
Linux and the rest of the world.

microvax2000 is the only one I've seen so far that will be a VXT (as a vaxstation2000) and boot off in infoserver.

So, consider the type of system you want to set up. After that, what the
disk gets called isn't so important.
--
PGP Key ID: 781C A3E2 C6ED 70A6 B356 7AF5 B510 542E D460 5CAE
"The Internet should always be the Wild West!"
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From Newsgroup: comp.os.vms

flexmcmurphy <plica2006@gmail.com> wrote:

Hello,

I am installing OpenVMS VAX 5.5-2H4 under SIMH and am confused by how standalone BACKUP assigns device names when booted from installation media.

This is where I got the ISO from (Server 1)

Setup (simplified):
- SIMH VAX (have tried MicroVAX 3900 and VAX 8600)
- OpenVMS VAX 5.5-2H4 ISO attached as an RQ device (read-only)
- Booting directly from the ISO into standalone BACKUP

In standalone BACKUP, the installation media always appears as DJAx
(device type RA60), not as DUAx, for example:

Available device DJA3: device type RA60

Without seeing your setup, I can't tell you exactly why yours
results in DJA, but here is the relevant parts of the config I
used to do this exact thing. I don't remember exactly where
I got the base of my vax.ini, but it was one of the top
google results.

set rq0 rauser=8192
set rq1 rauser=8192
### I suspect this is the bit you might be missing?
; Configure a CD-ROM drive (RRD40) on disk interface RQ3
set rq3 cdrom
attach RQ0 /home/sthomas/vax/oldvax/data/rq0-big.dsk
attach RQ1 /home/sthomas/vax/oldvax/data/rq1.dsk
attach RQ3 -r /home/sthomas/vax/oldvax/iso/VMS55.iso

Cheers,
Sam
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From Newsgroup: comp.os.vms

I think I have figured out what was happening here.
The device name (DUAx vs DJAx) assigned to the ISO file depends on what
SIMH version you are using:
SIMH v4.0-0 maintained by Mark Pizzolato:
https://github.com/simh/simh
Open SIMH v4.1-0
https://github.com/open-simh/simh
If your ISO file is small enough in size then with SIMH v4.0-0 (Mark
Pizzolato) you might get the device name: DJA1.
In my case I am trying to restore the save_set from an ISO of OpenVMS
v5.5-4H2.
Because the ISO is only about 204MB SIMH uses its internal logic
(autosize) to assign the ISO file a device type of RA60 because that is
the closest DEC device capacity drive that 204MB matches with. This is
what happens regardless if you start out with this in your ini file:
SET RQ3 CDROM
ATTACH RQ3 -r openvms_v5.5-4h2.iso
So SIMHv4.0-0 responds to a MRSP query from Standalone Backup with a
deviceID: (DJ - RA60) indicating that the device at that controller is
a removable device of type RA60. (DJ - Removable, DU Fixed). Standalone
Backup then uses it's own logic to translate this to a device name
DJA3.
If you disable AUTOSIZE then you will get DUA3 as the device name:
set rq3 cdrom
set rq3 NOAUTOSIZE
attach rq3 -r openvms_v5.5-4h2.iso
This is because SIMH v4.0-0 will now just respond to a MRSP query with
whatever device type you define in your ini file.
If you use Open SIMH v4.1-0 you will probably just get DUA3 as the
device name and not have to disable AUTOSIZE at all. I don't fully
understand how SIMH and Open SIMH differ in their device detection
logic but it seems that with Open SIMH if you put this in your ini
file:
SET RQ3 CDROM
ATTACH RQ3 -r openvms_v5.5-4h2.iso
Then Open SIMH WILL respond to an MRSP query that the device type is
CDROM and then Standalone Backup will see this as an RRD40 device and
create the device name DUA3.
CDROM device are also removable drives but whereas RA60 disks were
connected to MSCP controllers RRD40 disks were connected to DSA
controllers where any type of local disk were consolidated under DUAx
device naming. Not confusing at all!

Cheers,
Flex
-----Original Message-----
From: Sam Thomas <sam@noneya.com>
Subject: Re: SIMH + OpenVMS 5.5-2H4 standalone BACKUP: ISO appears as
DJAx not DUAx
Date: 18/12/25 17:05:41
Newsgroups: comp.os.vms
flexmcmurphy <plica2006@gmail.com> wrote:

Hello,

I am installing OpenVMS VAX 5.5-2H4 under SIMH and am confused by
how-a
standalone BACKUP assigns device names when booted from installation
media.

This is where I got the ISO from (Server 1)-a

Setup (simplified):-a
- SIMH VAX (have tried MicroVAX 3900 and VAX 8600)-a
- OpenVMS VAX 5.5-2H4 ISO attached as an RQ device (read-only)-a
- Booting directly from the ISO into standalone BACKUP

In standalone BACKUP, the installation media always appears as DJAx-a (device type RA60), not as DUAx, for example:

Available device DJA3: device type RA60

Without seeing your setup, I can't tell you exactly why yours
results in DJA, but here is the relevant parts of the config I
used to do this exact thing. I don't remember exactly where
I got the base of my vax.ini, but it was one of the top
google results.
set rq0 rauser=8192
set rq1 rauser=8192
### I suspect this is the bit you might be missing?
; Configure a CD-ROM drive (RRD40) on disk interface RQ3
set rq3 cdrom
attach RQ0 /home/sthomas/vax/oldvax/data/rq0-big.dsk
attach RQ1 /home/sthomas/vax/oldvax/data/rq1.dsk
attach RQ3 -r /home/sthomas/vax/oldvax/iso/VMS55.iso
Cheers,
Sam
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