"The early 90's had many UNIX workstation vendors.
There are plenty of models to choose from, many of which are
supported by Debian GNU/Linux. Alpha machines represent a good
place to start exploring the world of old computers, for two
reasons: First, there is good documentation available for them, and
second, they are compatible with many kinds of common PC hardware.
Documentation: There is plenty of documentation for old Alpha
workstations on the Net. Many operating systems support the Alpha
architecture, so there is no shortage of support pages, mailing
lists, and HOWTOs. The Alpha Linux page is a particularly good
resource. Furthermore, you can still download the original manuals
for many Alpha workstations from the old Digital FTP site. This
documentation can help you overcome both hardware and software
Compatibility: Alpha workstations are compatible with many kinds
of inexpensive PC hardware. For example, my Alpha workstations use
VGA, 10BaseT Ethernet, and PCI cards, just like the average PC. My
Multia workstations even have two PCMCIA card slots."