This section was contributed and was maintained for many
years by Martin Ostermann. (Thanks, Martin !) Currently Martin doesn't own a
Jensen anymore: updates for this section may be sent directly
The Jensen was the first Alpha PC that has been available
commercially from DEC. Not surprisingly, there are a few oddities
with it. This section is an attempt to help people getting
Linux/Alpha installed on a Jensen, and to provide additional
information operating Linux on the Jensen.
First off, there is no MILO for the Jensen. So it is unavoidable to
use Jensen's builtin
console. Unfortunately, it is severely
handicapped with respect to boot command line option processing.
Michael Schwingen there is now a new
loader that can work around these limitations.
Secondly, the Jensen SRM console cannot boot from a floppy. This used
to make bootstrapping Linux a real pain, until
Jim Paradis contributed a minilabel and
writeboot programs executable from the ARC console. These tools can be
download from the
AlphaLinux.Org Jensen Page.
The original version -- which is outdated and you should not use this
now -- is available together with a the JENSEN-HOWTO describing the installation
process in detail from
The Jensen is supported by
Red Hat Linux, but some things still cause trouble.
The Jensen differs from other systems in several ways:
- No MILO. It was already stated that there is no MILO for the Jensen. This is
because the firmware implementation of the Jensen differs somewhat
from the one on other systems. PALcode is the keyword to look for, if
your interested to know more.
- EISA-Bus. The Jensen has only got an EISA bus, no
PCI. Furthermore, it uses a very special addressing scheme for the
bus. While the kernel usually takes care of that in respect to device
drivers, it has to be taken care of by utilities that do i/o in user
space, like the X servers. Therefore you need special support from the
X server, which is available in XFree86 version 3.3 (or later) for S3
cards, available from
www.xfree86.org. You'll also find
other useful stuff there, ported by
like a ported SVGAlib.
If you're interested in details, watch for the keywords SPARSE vs
Note: Only S3 based cards are supported. The Compaq QVision,
which is one of the graphic cards originally shipped by Digital, is
not currently not supported by XFree86, and support for it is
unlikely to occur at all.
- RTC. Somehow it was managed to locate the real time clock
at a different place (I/O port 0x170 instead of 0x70 on all other
machines). Thus the original clock program will fail. A patched
version is available from
Martin Ostermann's Alpha Page.
- Firmware. Since the Jensen is the oldest machine around,
there are chances that you got a very old firmware. The date format
changed in newer version, which will cause an offset of 20 years. You
ought to get a
firmware update. WARNING: If you own an ELSA-Winner 1000
graphics adapter, don't update beyond version 1.7!
Otherwise you'll not be able to use your card in EISA mode. This is
probably due to a bug in the EISA BIOS of the card.
Know Problem and workarounds:
- Date and Time. Due to the location of the real time clock
and/or an old firmware. See above.
- Won't boot after firmware update. Aboot doesn't work with
new firmwares. It is known to work
with versions up to 1.7.
If you own an
ELSA-Winner 1000 graphics adapter and upgraded beyond firmware
version 1.7, the card won't work in EISA mode. Turn the card, so that
it is plugged in with its ISA side.
Maybe you want to downgrade you
firmware again. (Windows-NT 3.51 and 4.0 seem to work fine with firmware 1.7)
is now available from Digital's FTP server.
- aboot-0.x doesn't compile on recent kernels.
Get aboot-0.4 or above, it works with recent kernels.
- Won't automatic reboot after correct shutdown. Known
problem, with 2.0.x kernels. Apparently this has been solved with
recent 2.1.x kernels. I tried 2.1.88, and rebooting worked. But that
kernel version had other problems.
- Second serial port is unusable.
Accessing '/dev/cua1' will freeze the system immediately. You may test
this by issuing 'cat /dev/cua1', but I suggest that you put your
file-systems in read-only mode first. In case you need more serial
ports, it is no problem to install an additional serial buffer
card. In case you need this for a modem, you ought to do that
anyway, because the builtin ports are unbuffered (16450
compatible), not buffered ones (16550!).
Sometimes people tend to blame the Jensen for general Alpha related
problems. Please keep in mind that only the hardware is different, and
that in most cases the kernel handles the hardware access. Thus for most
programs it doesn't make a difference if they are being run on the
Jensen or any other Digital/Alpha machine.
You may ask yourself, how you can upgrade your system. Here are some
suggestions, but please note that I actually did not test most of this
stuff, I just collected information found on the internet:
- RAM updates.
4 MB, 8MB (dual-RAS aka doublesided), 16 MB, and 32 MB SIMMs produced
as late as summer of 96 have been reported to work, but I do not know
if a certain refresh cycles is required. Note that you need 36
bit true parity SIMMs (but only one of the 4 parity bits on each
SIMM is actually used, as Michael Schwingen confirmed).
- Video card.
Basically any VGA ISA or EISA card may work. Most actually do, if
you use the ARC console and Windows NT. Unfortunately, the SRM
console, which you need to boot Linux, is somewhat picky about the
cards it supports. It uses an Intel-x86 emulation to initialize the card
via its VGA-BIOS, and that one seems to be buggy.
If you want to run X, you need an S3 based card. Any S3 card (but,
not S3-Virge, etc), which has been accepted by the SRM console,
should work. Look at the XFree documentation for the XF86S3 driver for
So what is the Jensen all about? There is a some information
- The Evolution of the Alpha AXP PC (
by David G. Conroy, Thomas E. Kopec, and Joseph R. Falcone.
This describes the development leading to the Jensen system.
- Product announcement and description (
Postscript) by Digital. This is
an overview of the Jensen system components and options.
- PB22H-KB System Module -- Hardware Reference Information (
PDF) by Digital. This is an in-depth description of the Jensen hardware.