9. Jensen (DEC 2000/DECpc 150/Highscreen AXP)

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 to me

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.

9.1 Installation

First off, there is no MILO for the Jensen. So it is unavoidable to use Jensen's builtin SRM console. Unfortunately, it is severely handicapped with respect to boot command line option processing. Thanks to Michael Schwingen there is now a new aboot 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The original version -- which is outdated and you should not use this now -- is available together with a the JENSEN-HOWTO describing the installation process in detail from ftp.digital.com.

The Jensen is supported by Red Hat Linux, but some things still cause trouble.

9.2 The Jensen is different

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 Stephan Kanthak, like a ported SVGAlib. If you're interested in details, watch for the keywords SPARSE vs DENSE memory.

  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.

9.3 Known Problems

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) This version 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.

9.4 Hardware Issues

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 detailed information.

9.5 Miscellaneous Information

So what is the Jensen all about? There is a some information available online:

• The Evolution of the Alpha AXP PC ( text/ Postscript) by David G. Conroy, Thomas E. Kopec, and Joseph R. Falcone. This describes the development leading to the Jensen system.
• Product announcement and description ( text/ 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.