3. Project environment
3.1. LINUX operating system
Linux is a free Unix-like operating system, first developed by Linus Torvalds on an Intel platform; “official” releases exist since October 1991.
It has now been ported to Digital/Alpha and ports to other machines, including PowerPC andPowerMAC, are under way.
3.1.1. Linux on Intel/i386
There are many distributions of Linux for the Intel platform; we installed the Slackware distribution, based on the Linux 1.1 version.
We downloaded it from the ftp site: sunsite.unc.edu:/pub/Linux/distributions/slackware
The version we installed was Linux 1.1.59, available since October 1994. Since then, newer versions have been released, but we stuck to this version throughout the project since it worked well, and because all the packages it included were easily available in source form (see below).
3.1.2. Source code for Linux commands used by the project
We downloaded the source code of the Linux commands from the ftp site: sunsite.unc.edu:/pub/Linux/distributions/slackware/source.
This means that the versions of commands available on our development machine for Linux/i386 were matching the source code we used as base for the project, except in a few cases for which the source code had been revised.
3.1.3. Linux on Digital/Alpha
For the Alpha platform, Linux is available from the BLADE distribution, and more recently from the Red Hat distribution.
A 32-bit version of Linux/Alpha was first released in January 1995; then a 64-bit version was available in November 1995, which included most of the capabilities provided by the Linux/Intel system. We downloaded the BLADE_0.3 release, consisting of more than thirty floppy images, from the ftp site: ftp.digital.com:/pub/DEC/Linux-Alpha
Since December 1995, another Linux/Alpha distribution has become available from the RedHat company; it is built from the same components, but newer versions, as the BLADE release.
An interesting feature of the current Linux/Alpha ports, is that they provide rather extensive binary compatibility with Digital Unix. This compatibility has been used to cross-build on Digital Unix for Linux/Alpha, and also for a few features which were not available in the Linux/Alpha BLADE release.
3.2. Hardware platforms and environment
The Intel platform was an Intel/i486 PC machine, with most disk space available through NFS.
The Digital/Alpha platform was built specifically for this project, around a Digital AXPpci 33 motherboard. In fact, at the time we set-up the machine, the Linux/Alpha ports were only running on a few Alpha-based machines.
A Linux kernel had to be rebuilt for this machine in order to add support for the 3COM Ethernet board we used, and for the NFS-client capability. Most disk space was thus available through an NFS file system, shared with the Intel platform.
3.3. TenDRA technology
We started the project on an Intel platform with a snapshot of the TenDRA technology from April 1995, which included support for the Linux/Intel platform. This snapshot was based on the ANDF 3.1 specification.
We switched to the November 1995 TenDRA snapshot, based on ANDF 4.0, when we setup the second platform, in order to use the tools for the Digital Unix/Alpha platform. Because of the high degree of compatibility between Digital Unix and Linux on Alpha, we could use the TenDRA technology on a DigitalUnix/Alpha platform to cross-build executables for the Linux/Alpha platform.
The ANDF 4.0 intermediate file format is not upward compatible with the ANDF 3.1 one, which required that we rebuild the intermediate ANDF files for the Linux commands we had already built.
ANDF 4.0 contains increased capability, though not required by this project, and forms the basis for the X/Open preliminary specification XANDF.