This writeup encompassess all of the IRIS 1x00 series systems, there is simply not enough information to validiate the creation of separate nodes/writeups for each system.
Silicon Graphics was founded in 1982, and released their first product, the IRIS 1000 terminal, in 1983. The IRIX 1x00 series are interesting in that they used modified mainboards based on the SUN (Stanford Univeristy) designs licensed from Andy Bechtolsheim before the well-known company was founded. These boards were labeled PM1 in 1000/1200 and PM2 in 1400/1500 and were the only non-SGI designs.
The IRIS 1000/1200 were designed as diskless systems intended as terminals, used a less powerful 8 MHz Motorola 68000 processor, and had around 3-4 MB of Micro Memory Inc. Multibus RAM. Their more powerful 1400/1500 counterparts had a 10 MHz Motorola 68010, and 1.5 MB of RAM. The 1400 used a 72 MB ST-506 disk, and the 1500 used a 474 MB SMD disk. They were sold as workstations, and came out a year after the 1000.
All IRISes came with a 30 Hz interlaced monitor.
Below is a excerpt from a sale post on Usenet which discusses some interesting things about the IRIS 1400 (Notes in bold).
The IRIS 1400 includes a stand-alone, 68010-based UNIX environment (System V with 4.2 BSD enhancements such as demand paging), real-time 3D color graphics using the Geometry Engine, and Ethernet (Type: Excelan EXOS/101) with IP/TCP or XNS protocols. The Geometry Engine, a custom VLSI graphics processor developed under an ARPA contract at Stanford, performs over six million geometric floating point operations per second.
The IRIS 1400 comes standard with 1.5 MB of CPU memory, 8 bit-planes of 1024x1024 image memory, and a 72 MB Winchester disk and controller. Options include additional CPU and image memory, a floating point accelerator, and large capacity disk and tape systems.
Not suprisingly, the original IRIX 1x000 series machines are rather elusive and collector's items.
Sources
SGI IRIS FAQ
http://sgistuff.g-lenerz.de/