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NetBSD/pmax Frequently Asked Questions

NetBSD Questions

Hardware Questions


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NetBSD Questions

Can NetBSD/pmax be run on R4000 or R4400 CPU systems? (top)


NetBSD/pmax now supports the r4000 CPU. A kernel built with both the MIPS1 and MIPS3 options, as well as the relevant DEC_ options, (such as the GENERIC kernel) will boot on all currently supported R2000/R3000 systems and R4000 systems.

The Notes on System Models page has a complete list of supported machines that NetBSD/pmax runs on.

Can NetBSD/pmax boot diskless? (top)

Yes. Look at the Diskless NetBSD HOW-TO for information on booting NetBSD/pmax diskless. There's also an old Netbooting NetBSD/pmax page that you may find useful.

My SCSI tape drive(s) aren't detected. (top)

The NetBSD kernel expects to see tape drives at SCSI IDs 4 or 5. They should probe as tz devices with a suitable kernel.

This restriction will be lifted with the move to a machine-independent SCSI driver.

If the drive still doesn't probe, check that the PROM detects the drive (using cnfg 3 for devices attached to the base system SCSI controller).

Hardware Questions

What is the difference between a DECsystem and a DECstation? (top)

A DECsystem is a machine with no graphics card and a DECstation is a machine with a graphics card. Other than that, they're identical. For example, when you buy a CPU upgrade from (in the past) Digital, you got the CPU board and two badges, one each with DECsystem and DECstation.

What SIMMS can be used in the Personal DECstation 5000/25 or DECstation 5000/125? (top)

DEC 2MB or 8MB 80pin partitioned SIMMs or compatibles from, e.g., Kingston. PC SIMMs will not work. The PROMs will not permit mixed 2MB and 8MB in a single system.

Are SCSI CDROM and floppy drives supported? (top)

Yes. They are supported by the machine independent cd(4) and sd(4) drivers.

Are the accelerated video cards supported? (top)

As of 1.5, the framebuffers with kernel support are: the baseboard framebuffers on the 2100/3100 and Personal Decstations, and the TURBOchannel 2-D mfb (PMAG-AA), cfb (PMAG-BA), sfb (PMAGB-BA), px (PMAG-C) and pxg (PMAG-D, PMAG-E and PMAG-F).

The SFB driver does not use the hardware accelerator at all; it treats the framebuffer as a larger cfb. At some point the NetBSD/alpha sfb support may be merged.

The Notes on System Models page has a full list of supported and unsupported graphics cards.

What external SCSI cable fits a DECstation 3100 (top)

It is DEC part # BC09J-03 which is a 68pin female to 50pin centronics male SCSI cable. Ficomp may stock some of these cables.

Does the floppy drive work? (top)

Floppies should work, either in a running kernel or for booting, in all but the Personal DECStations. In the Personal DECStations, the floppy was apparently designed to be used for transferring data via sneakernet, and nothing else. In the other pmaxes, the floppy appears to be a very small SCSI device, so it's perfectly usable.

Consoles on the DECstation 5000 series machines (top)

The DECstations (and DECsystems) can use a serial terminal instead of the keyboard/mouse and graphics device.

If a keyboard isn't detected by the PROM, then a serial port will be used as the console. Port settings are always 9600,n,1 (speed 9600, no parity, 1 stop bit). Use the serial port marked as number 3 on the 5000/xxx machines (that's the one furthest from the power connectors), or the DB25 port on the 5000/xx machines.

To always force a serial console (overriding the keyboard/graphics), set the PROM environmental variable console to the value s (using setenv console 's' ).

Probably the most useful console variable setting is *, which has the system probe for the graphics adapter in the lowest-numbered TURBOchannel slot (including the onboard framebuffer, in the case of the 5000/xx machines).

The PROM has some intelligence - setting the console to, e.g., an empty TURBOchannel slot isn't a problem (it will time-out and return after a short time). You don't need to switch off or reboot between changing these settings.

The osconsole variable is set automatically by the system. It indicates the slot numbers of the devices used for console input/output.

Consoles on the DECstation 2100 and 3100 machines (top)

To set up a serial console, the keyboard and framebuffer need to be removed. Leave the mouse or a suitable mouse terminator (DEC part no. 12-25628-01) connected to the system. A quick terminator can be made by shorting pins 2 (Tx) and 4 (Rx):

            top of unit
              (     )
             ( o o o )
            (         )
           | o ||||| o | <--  Connect these two pins together
            (         )
             (  o o  )

(As seen from the rear of the system unit)

The framebuffer is the single, fairly large memory board on the left-hand side of the mainboard, behind the system RAM.

Connect a null-modem cable from the printer serial port (marked with a printer icon). The serial ports are actually RS-423, but a compatible RS-232 style cable can be made. The console port settings are 9600,n,8,1 as usual.

DECstation won't autoboot after setting bootpath/haltaction etc. (top)

Modifications to any PROM environment settings aren't actually written to NVRAM until the OS has reached a certain runlevel. You'll need to boot the OS and shut down normally before the settings become permanent.


How do I reset the PROM NVRAM? (or, I'm stuck with a R>  NVRAM prompt) (top)

This procedure works on the 5000/xx, 5000/1xx and 5000/2xx machines.

  • First locate the two-pin NVR connector. This connector is in a different place on each model. Looking from the front of the machine:
    • 5000/xx: It's located to the left of the power connector and marked "nvr".
    • 5000/1xx: It's located to the right of the power connector and marked "nvr".
    • 5000/200: It's located at just in front of the left end of the left-most TURBOchannel connector, next to a larger four-pin connector. It is not marked.
    • 5000/2[46]0: It's located at the edge of the motherboard near the back of the middle power supply fan, next to a larger four-pin connector. It is not marked.
  • Slide a jumper over the NVR connector. Jumpers used on older SCSI disks will do the job nicely.
  • Turn on the system power and wait for the console prompt to appear.
  • When the console prompt appears, turn off the system power.
  • Remove the jumper from the NVR connector.

You should now be done. When you re-apply power to the system, you should be greeted with a >>  prompt.

What does 'FNF' mean when a boot fails? (top)

This is the response generated by the PROM when it attempts to boot via tftp and cannot find the file - "File Not Found".

DECstations do not respond to arp requests while booting (top)

The pmax boot proms have a bug in that once they are configured with an IP address, they do not respond to ARP requests. The system from which you are booting them will need to enter an arp(8) entry when responding to the initial request, or you could set up some other NetBSD box to proxy arp for them.

Some useful PROM commands (top)


List available commands (help).


List installed hardware, including CPU type, RAM, ethernet interface address, SCSI controller and graphics hardware.


Test hardware - e.g., 'test mem'

boot [options] [#/dev/path] [arguments]

Boot the machine.


-n Load system software, but stay at PROM monitor.
-z # Wait # seconds before booting


# TURBOchannel slot number. Use cnfg to list slot contents
dev 'tftp' or 'mop' for network booting, rzN to boot from scsi disk ID N
path Optional file


-a Autoboot to multiuser
(others) (to be expanded)


boot 3/rz2/netbsd -aN
load and boot "netbsd" with argument -aN from the filesystem in SCSI ID #2 disk of baseboard SCSI channel
boot 0/rz4/otherimage
load and boot "otherimage" from the filesystem in SCSI ID #4 disk of SCSI channel at TC slot 0 (like PMAZ-A).
boot 3/tftp
start BOOTP/TFTPBOOT sequence using baseboard LANCE. [ I donno whether this can take filename or argument designations like 3/tftp/nfsnetbsd.ecoff -aN]
boot 1/tftp
start BOOTP/TFTPBOOT sequence using LANCE device at TC slot 1 (like PMAD-A).
boot 3/mop
start MOP boot sequence using baseboard LANCE.

setenv variable value

Set PROM environment variables. Many of these control the way the PROM boots the system.

setenv boot "3/rz2/netbsd -aN"
Default parameters for boot command
setenv console "s"
Force serial console
setenv console "*"
Select console probing TC slots
setenv haltaction "b"
Boot automatically after poweron
setenv haltaction "h"
Stay PROM monitor after poweron
setenv haltaction "r"
Reference Card states "Restart the worksystem software without booting; boot only if the restart fails."
setenv testaction "q"
Run the quick, less thorough self-test
setenv testaction "t"
Run the complete, thorough self-test

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