History of IRIX
by Ryan Thoryk
email: ryan at tliquest dot net

Updated January 18, 2007

A good portion of version numbers came from this Usenet thread

Contents:
IRIX 6.x
IRIX 5.x
IRIX 4.x
IRIX 3.x
IRIS 4D1 Unix 2.x and 1.x (IRIX 2.x and 1.x)
IRIS GL2 Unix (IRIX 0.x)

Information on the move from 68k to MIPS
IRIX name
Misc stuff (IRIS name, IP name and numbering, etc)

Version tables

6.x
6.5.30 - 08/16/06
6.5.29 - 02/08/06
6.5.28 - 08/03/05
6.5.27 - 02/02/05
6.5.26 - 11/03/04
6.5.25 - 08/04/04
6.5.24 - 05/05/04
6.5.23 - 02/04/04
6.5.22 - 11/05/03
6.5.21 - 08/06/03
6.5.20 - 05/07/03
6.5.19 - 02/05/03
6.5.18 - 11/08/02
6.5.17 - 08/07/02
6.5.16 - 05/08/02
6.5.15 - 02/06/02
6.5.14 - 11/07/01
6.5.13 - 08/08/01
6.5.12 - 05/09/01
6.5.11 - 02/07/01
6.5.10 - 11/08/00
6.5.9 - 08/09/00
6.5.8 - 05/09/00
6.5.7 - 02/10/00
6.5.6 - 11/03/99
6.5.5 - 08/06/99
6.5.4 - 05/11/99
6.5.3 - 02/09/99
6.5.2 - 11/17/98
6.5.1 - 08/24/98
6.5 - 06/98
6.4 - 11/96
6.3 - 09/96
6.2 - 03/96
6.1 - 07/95
6.0.1 XFS - 03/95
6.0.1 - 12/94
6.0 - ?

GUIs:
6.2 to current: X11R6, 4DWM window manager, Indigo Magic desktop (renamed to IRIS Interactive Desktop possibly at version 6.5)
6.0-6.1: X11R5 (source)
6.5 Screenshot

5.x
5.3 TIRIX - 06/95 (Trusted IRIX 5.3)
5.3 XFS - 12/94
5.3 - 11/94
5.2 - 03/94
5.1.1 - 09/93
5.1 - 9/93
5.0.1 - 06/93
5.0 - 3/93

GUI: X11R5, 4DWM window manager, Indigo Magic desktop environment
5.3 Screenshot

4.x
Versions are abbreviated with "4D1-" representing the 4D line of machines
4.0.5MM (Multimedia release)
4.0.5J
4.0.5IPR
4.0.5IOP - 04/93
4.0.5H A360 MCO
4.0.5H A360
4.0.5H - 03/93
4.0.5G
4.0.5F
4.0.5 EPL
4.0.5E
4.0.5D
4.0.5C
4.0.5A (really revision B)
4.0.5
4.0.4T (second Trusted IRIX)
4.0.4B
4.0.4 - 03/92
4.0.3 - 03/92
4.0.2 - 03/92
4.0.1T (first Trusted IRIX)
4.0.1 - 11/91
4.0 - 09/91 (first version that used X11)

GUI: X11R4, 4DWM window manager, and IRIS Workspace desktop environment
4.0.1 Screenshot

Announcement of IRIX 4:
"IRIS Indigo runs IRIX(tm) 4.0, Silicon Graphics' enhanced version of
the UNIX(R) operating system. IRIX is POSIX, X/Open(tm) XPG3 and FIPS
151-1 compliant. In IRIX 4.0, the X Window System(tm) (X11/R4) is
merged with the IRIS GL interface and Adobe's Display PostScript(r)
for flexible rendering."

Info on 4.0 shipping with the IRIS Indigo
"Irix 4.0 is based on Unix System V Release 3 with Berkeley enhancements" (the BSD enhancements were from BSD 4.3, like 3.x)

3.x
Versions are abbreviated with "4D1-" representing the 4D line of machines
3.3.2 - 12/13/90
3.3.1 - 09/04/90?
3.3 - 06/29/90?
3.2.3
3.2.2
3.2.1
3.2A
3.2 - mid 1989
3.1.2
3.1G - 08/04/89
3.1F - 06/05/89
3.1E
3.1D - 02/27/1989
3.1C
3.1B
3.1A
3.1 - 04/07/89
3.0.1
3.0B
3.0A
3.0 (first regularly noted MIPS version) 10/6/88

GUI: Sun NeWS with SGI 4Sight
3.3 Screenshot

Excerpt from above link on IRIX 3:
"IRIS-4D Series Superworkstations include an enhanced version of the UNIX V.3 operating system called IRIX. IRIX incorporates many features of the Berkeley 4.3 BSD UNIX release, plus many local system enhancements to support real-time graphics. This extended software environment permits easier connectivity and improved system throughput. Other operating system enhancements include the Extent File System (EFS), a unique UNIX file structure handler that improves file handling performance two-fold over the standard System V file architecture. EFS is modified so it writes files in large extents to the disk. By writing disk files in this way, EFS improves disk seek times, which results in improved overall system performance."

2.x and 1.x
This was an early and short-lived line for MIPS, and was not referred to as "IRIX" until later, with the 3.0 release.
Originally SVR3 with BSD 4.2 and SGI Extensions
Versions are also abbreviated with "4D1-" representing the 4D line of machines, like 3.x
The Typewritten site has a copy of 2.0, and the master tape is labeled "4D1-2.0 Standard System Tape 1 11/18/87".
In some of the software, there are references to 1.x releases.
4D1-2.3
4D1-2.2b
4D1-2.2 - mentioned here
4D1-2.0 - Mid 1987
4D1-1.1
4D1-1.0 - late 1986 or early 1987

GUI: MEX (need more information)

0.x / IRIS GL2 Unix
The series for the Motorola 68000 line of processors was a different operating system provided by UniSoft, and was basically UniSoft UniPlus System V with SGI customizations. I refer to it as IRIS GL2 Unix, but it can also be referred to as the IRIX 0.x series. There was a separate versioning sceme reflecting a models/features mix. It was used on the SGI 1000, 2000 and 3000 lines of workstations and terminals. Some of the 1000's were diskless terminals and thus had no OS. These systems used the MEX (short for Multiple EXposure) windowing system for graphics. This PDF has some info and pics of a graphics app being used on MEX.
The 1.5 kernel was called (in the following documents) "Silicon Graphics System V". This is because many vendors simply adopted a standard Unix for their systems, but didn't offically give their adaptation/fork a name until later on. See below for more info on this (section on the Unix trademark).

Some info here (IRIS FAQ)

Versioning sceme is this:
(GL version)-(W/T)(2/3).(OS release number)

GL refers to the IRIS Graphics Library and was either GL1 or GL2 (GL is the early precursor to OpenGL)
About the W and T: T means Terminal (shown in an invaluable document) and W means Workstation.
The "2" refers to machines with 68010 processors, while "3" refers to ones with 68020's (more info below).

Full name release history (known versions):
GL2-W3.6 - 1987
GL2-W3.5r1
GL2-W3.5 - December 1986
GL2-W2.5
GL2-T3.4
GL2-T2.4
GL2-W2.4 - March 1986
GL2-T3.3.1
GL2-T2.3.1
GL2-W2.3

"W2" and "T2" (68010) run on the IRIS 1400, 1500, 2000, 2200, 2300, 2400, 2500 machines
"W3" and "T3" (68020) run on the IRIS 2300T, 2400T, 2500T, 3010, 3020, 3030, 3110, 3115, 3120, 3130 machines

If you cut off the "GL2-W3." off the top one, it would be "6" or "Release 6", meaning IRIS GL2 Unix Release 6.0, or IRIX 0.6.

So the versions would be:
0.7 (seen on the Typewritten site)
0.6 - 1987
0.5 - December 1986
0.4 - March 1986
0.3.1 (earliest release seen mentioned so far online)
0.1.5 - mid 1984
0.1 - 1983

The also invaluable workstation guide has vital kernel version information:
Kernel number: System 5 UNIX #135 [Fri May 4 11:15:09 PST 1984]
Release: Beta-1.5
(C) Copyright 1983 - UniSoft Corporation
(C) Copyright 1983 - Silicon Graphics Inc.

This kernel would refer to IRIS GL2 Unix 1.5 (or IRIX 0.1.5).

From this page:
"Since its inception in 1982, SGI and its customers have relied on the power and stability of IRIX to conduct their critical businesses."

This quote isn't all that true, since the first machines were simply terminals with no OS. IRIS GL Unix was based on UniSoft Uniplus System V Unix (UniSoft ported various versions of Unix to 68k for a number of companies), and later on included BSD 4.2 enhancements (don't know about pre-4.2 though). According to GL2-W3.5 Workstation release notes, the BSD 4.3 TCP/IP subsystem was merged into that release (release 5). For comparison, Sun Microsystems' SunOS originated from Uniplus Version 7, and that version is commonly referred to as SunOS 0.x.

Quote on the history of IRIX from a Usenet post:
"...with System Software 1.6 and 1.7(beta) installed. (ironically, in light of the name of this thread, this was way before anyone ever thought of rewriting/rebranding the OS as IRIX - the 'System Software' was still the original 'System V with BSD enhancements' UNIX as provided originally for SGI by UniSoft. IRIX came slightly after the transition to the MIPS architecture with the introduction of the 4D/60)."

Information on moving from the Motorola 68k architecture to the MIPS platform from MIPS Computer Systems.

MIPS was a company that adopted the Stanford MIPS processor architecture, and formed their company around continuing development of that architecture. They also manufactured their own computer systems with MIPS cpus, although they (as an independent company) didn't last very long due to a very vicious market at the time, but were fortunately bought by SGI. They had their own proprietary Unix for their systems known generally as RISC/os (no relation to Acorn RiscOS), and is sometimes referred to as MIPS OS, and the internal was UMIPS (this shows up when using the uname command). I have a copy of RISC/os 4.52 (but no machine or emulator to run it on) and in many header files the OS itself is called UMIPS.

MIPS Computer Systems was purchased by SGI in 1992, and renamed MIPS Technologies in 1998. Another reference here.

IRIX and MIPS:

There's an article that says this:
"During 1Q86, we were bringing up UNIX on MIPS chips."
Now that had to have been either said by someone at MIPS or SGI.

It seems that the entire RISC/os was not actually merged with IRIX (this is because SGI didn't own MIPS until later on), but was probably used as code foundation in order to quickly port IRIX over to MIPS (and so I'm guessing that there should be fragments of RISC/os code in IRIX that MIPS probably provided). After the MIPS acquisition in 1992, SGI continued some support for RISC/os (since they now owned it), but phased it out; around this time they could have incorporated portions of that OS into IRIX.

This is interesting:
"The RISCos driver source was supplied with every system, and we did donate the source to Berkeley."

RISC/os seems to have been started around 1985, and the last line of it seems to have been 5.0x - sources here here here and here

This book might give an interesting history.

Some roots of RISC/os:
"MIPS computers running RISC-OS can support four different personalities: default, BSD 4.3, System V.3, and System V.4 (older versions of RISC-OS don't support V.4)."

This page shows that MIPS developed systems until around mid 1992, due to financial troubles, and then after the merge with SGI they focused entirely on processor development.

Sidenote - I'm currently putting information together to make a history of RISC/os. This information is very scarce, but there should be great deals of information in old magazines at libraries. I found some pictures of a very old version of IRIX (either 3 or 4) in one, and once I find it again, I'll scan it - I think it was in a copy of Unix Magazine from the early 90's.

IRIX name

So far it seems that the operating system was referred to as IRIX starting around version 3.0. I'm looking for earlier references. In the comp.sys.sgi.admin usenet archives, a person claims (on 1/7/89) their system is running
"IRIX System V Release 4D1-3.13809261636" - which is version 3.1
The earliest mention of IRIX in the ARL archives is dated 8/7/88 and says "Several people have asked for what I did to make ksh filename handling work under IRIX"

A quote I have above from a Usenet post states this:
"[The name] IRIX came slightly after the transition to the MIPS architecture with the introduction of the 4D/60)."

The IRIS acronym (used in the IRIS line of 68k machines, other machines, and software) stands for Integrated Raster Imaging System (reference).

From a Usenet message in 2002:
"Now, historically, IRIX derives from the first Silicon Graphics products, which contained their graphics engine, and which were called IRIS machines, for Integrated Raster Imaging System. "IRIX" is simply a portmanteau word combining IRIS and UNIX."

An interesting take on the name comes from the website of a company ironically called IRIX Pharmaceuticals (I wonder if they're familiar with SGI? haha). They have a page called "Meaning of IRIX" which states "The name 'IRIX' is derived from the ancient Greek language. It directly translates to "falcon." It is the symbol of strength, excellence, and empowerment." - seems to follow the vision SGI has had.

Misc stuff

A quote from Jim Clark in a Usenet message in 1999 on the meaning of "IRIS":
"IRIS was a name chosen at random when I was submitting the final copy of the Geometry Engine paper to SIGGRAPH in late 1981. The final draft contains an interesting "keyword", as you'll see by looking at the image file created by scanning it in (paper.rgb).
"Marcia Allen (who was the secretary shared by me, Forest [Baskett] and John Hennessey) had a picture of an Iris on her bulletin board. I was reviewing the draft when I discovered that SUN Microsystem's had been formed. SUN had alway's meant Stanford University Network, and "SUN Terminal" was sprinkled throughout my paper. I said I'd be damned if I was going to give the impression that the Geometry Engine was part of SUN Microsystems, so I had to quickly come up with a new name, since the paper had to be sent in that day. Whimsical "Apple" worked, so why wouldn't 'Iris'."

The "IP" name designation to systems means "Inhouse Processor". Reference and another one
The "PM" designation (before IP) is still currently unknown to me, but this page says "PM1 - based on a design licensed from Andy Bechtolsheim, Stanford (before SUN)."

On IP numbering:

"IP1 never officially existed. If anything, it was a relabelling of the PM2 board as used in the IRIS 1400, 1500, 2000, 2200, 2300, 2400 and 2500. The first actually used IP series board was the IP2 as used in the 2300T, 2400T, 2500T and 3000 series machines. The main distinction between the PM and IP boards were that the PM were based on reference boards developed at Stanford University whereas the IP boards were (and still are, i hope ;) developed in house by SGI themselves (although often based on reference boards from MIPS - explicitly the case for the original IP4 boards used in the 4D/50; the first of the MIPS machines).
"Or perhaps the IP1 was a prototype of the "Turbo" 68020-based motherboard that eventually became the IP2.
"The antics of the IP numbering system are quite interesting, though - I've got a Personal Iris 4D/20 which is labelled up as a IP6.5 - and appears to be an IP12 complete with R3000@20MHz - but underclocked to 12MHz to render it functionally equivalent to a IP6. Dave Olson states in the past that at the end-of-life of the 4D/20 SGI ended up underclocking (possibly slightly defective) 4D/25s and selling them as 4D/20s - although makes no reference to changing the IP number on those boards. When I get a chance I intend to replace the crystal with a 20MHz one and see what happens."

SGI's archive of comp.sys.sgi messages starting on April 11, 1989

Info-Iris messages from ARL start on July 15, 1986