The Sun Ultra 1 was introduced, along with the Ultra 2, in November 1995, releasing the first iterations of the 64-bit UltraSPARC chip to the world. At the time, the Ultra 1's scores in SPECint92 and SPECfp92 (252 and 351, respectively) pushed it to the top of the workstation market.
The Ultra 1 came in a series of models depending on the clock speed of its CPU and the availability of high speed graphics: the 140 model had a 143 MHz CPU, the 170 had a 167 MHz CPU, and later on a 200 MHz version came out as well, though this was not available at launch. The 140E and 170E models (also called Ultra1 Creator) drop one SBUS connector and add a new high-speed bus port (UPA) that allows you to use what was, at the time, a high speed 24-bit graphics card. The Ultra 1 comes in the classic Sun pizza box casing, familiar to anyone who has used an earlier SPARCstation. All versions come with built in 100 Mbit Ethernet, internal and external SCSI, and an array of serial, parallel, and sound ports. All versions support up to a gigabyte of memory, which at the time was pretty phenomenal.
The Ultra 1 is not exactly top of the line anymore, but makes a very solid small server (I use mine for DNS, NTP, and intrusion detection using Snort), especially thanks to the easy to use serial console. It can run NetBSD, OpenBSD, Linux, or Solaris. Unfortunately, while FreeBSD does run on most 64-bit Sun machines, it does not run on the Ultra 1. I would recommend not using a recent Solaris on these machines due to the fairly slow clock speeds; a NetBSD or OpenBSD install is much easier on the CPU.
All models of the Ultra1 use SCA drives, Sun-style SIMMs, and SBUS peripherals, making add-ons fairly expensive compared to commodity parts using IDE or PCI. However, prices on these machines have dropped substantially in the nearly 10 years since their introduction. The initial pricing for a Creator 170E with 64 megabytes of RAM, a 2 gigabyte disk, and a 20-inch color monitor was $25,995. This spring, I picked up a Creator 170E, with 512 megabytes of memory and a 18 gigabyte disk, for $25, a price reduction of over 1000, even ignoring the 8-fold increase in the size of both main memory and permanent storage.