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Ian Mapleson's Second Hand Buying Advice for Indy web site is the ULTIMATE in used Indy information.

Also see Ian's SGI Advice and Technical Data site for more excellent SGI information.

The (way outdated) SGI FAQ is online at Texas A&M; University.

What's an SGI Indy? The Indy is a Unix workstation built by Silicon Graphics Incorporated of Mountain View, CA. Introduced in 1993, it uses the MIPS CPU (several different CPU modules were shipped by SGI), and runs SGI's Unix operating system called IRIX. Irix is mainly AT&T SVr4 based, but has many BSD type extensions and utilities. There is a port of Linux for the Indy, but it's horribly incomplete and pretty much not worth bothering with. Get IRIX.

The Indy has been sold by several companies as an OEM (original equipment manufacturer) product. In Germany, the box is still blue, but the Indy is labeled Siemens/Nixdorf RW410. These are R4000 100 MHz, with all original SGI parts. In the US, Indys may have been sold with a Tandem label, and were black. Here is a picture of a Tandem badged Challenge S along with a picture of the label on the bottom of the unit. The Challenge S is very similar in design to the Indy, and uses many of the same parts, such as the CPU modules, power supply, drives, and RAM. The Challenge S uses a different chassis (no holes cut in the back for keyboard and mouse), and an Indy motherboard with chips unstuffed (missing), like the VINO video, audio, keyboard/mouse interface, etc.

Here is some marketing hype for the Indy workstation (from SGI's web site).

  • AUI and 10Base T Ethernet connections for convenient and flexible standard networking
  • Standard ISDN wide-area networking interface for video conferencing, Internet access, and emerging media applications over ordinary telephone lines
  • Built-in video connections with a digital port, S-video port, and composite analog port supporting NTSC/PAL formats
  • Audio interfaces for CD-quality audio applications
  • SCSI-2 connection for up to five additional external devices such as disks, CD-ROMs, and scanners
  • Maximum expandability with GIO expansion ports for professional video options, video compression, additional networking interfaces, and third-party add-on cards
  • Macintosh-compatible RS-422 and RS-232 serial ports for easy integration with modems, printers, and more
  • Bidirectional, programmable 8-bit parallel port for easy access to a variety of printers, scanners, and other devices
  • Monitor connector for high-resolution (1280 x 1024) and low-resolution (1024 x 768) color monitors up to 76Hz
  • Standard PS/2(TM) interface for 3-button mouse
  • 170-watt autoswitching power supply for operation anywhere in the world
  • StereoView(TM) hardware interface for virtual reality and advanced graphics applications



The Indy motherboard is silk-screened "IP24". But hinv reports IP22. This is regardless of CPU module installed. This document will use the term "IP24" motherboard.

The motherboard is a highly integrated 12 layer (!) PCB measuring 8.25" x 10.75". It has a dozen or so custom ASICs (application specific integrated circuits) of very fine pitch soldered to both sides of the board. Component level repair on these boards is extremely difficult, and would be very expensive. Because of the integration and single board design, if any one system fails (e.g. a serial port), usually an entire motherboard replacement is required. The board has the connectors for all the above listed features on the "back" of the board, accessible through cutouts in the metal Indy chassis. Connectors on the motherboard are:

  • Qty. 5 stereo 1/8" phone jacks, for headphone, microphone, speakers, etc.
  • RCA jack for composite video input
  • SVideo 4 pin Mini-DIN
  • 60 pin Indycam connector (same physical connector as Cisco multi-serial ports - don't try this at home. Or work
  • 15 pin AUI network connector
  • RJ45 ISDN connector
  • RJ45 10BaseT network connector
  • 2 Mini-DIN 6 pin PS/2 compatible mouse and keyboard ports
  • 2 Mini-DIN 8 pin Mac compatible serial ports
  • 50 pin SCSI-2 connector
  • DB25 female bidirectional parallel port (PeeCee compatible)


The Indy boot EPROM is a 27C4001 40 pin EPROM, designated U58 on the IP24 motherboard. It is located UNDER the graphics board, which must be completely removed to gain access to the EPROM. I have seen versions 004 through 008, and 011. The 008 seems to be the most common.Jussi Niemelä from Finland has actually seen a version 003, on an R4000 Indy. The R5K CPU module requires a version 011 boot EPROM. In the PROM monitor, the command 'version' will list the boot EPROM version. The 008 version shows:

PROM Monitor SGI Version 5.3 Rev B7 R4X00 IP24 Feb 16, 1995 (BE) 

While a version 011 shows:

PROM Monitor SGI Version 5.3 Rev B10 R4X00/R5000 IP24 Feb 12, 1996 (BE)

(Note that the 5.3 has no relation to the version of Irix, as the PROM monitor knows nothing about Irix)

CPU module

The Indy CPU module sits on a daughterboard in front of the motherboard, and is connected to the IP24 motherboard via 2 96 pin connectors. CPU modules contain the CPU clock crystal oscillator, and no jumper changes (there aren't any jumpers anyway) are required when installing a different CPU family or speed, other than the boot EPROM version. 011 must be used for any R5000 CPU module.

If you change from an R4x00 (MIPS 3 CPU) to an R5000 (MIPS 4 CPU), you WILL have to re-install IRIX. It may work when going from R4x00 to R5000, as the MIPS 4 instruction set is a superset of the MIPS 3 set, but it will not work if you go from R5000 to R4x000.

There have been reports on usenet of people "overclocking" R5000 Indys, from 180 MHz. To 200 MHz., by replacing the 45 MHz. Crystal oscillator with a 50 MHz. Oscillator. The CPU clock multiplier in the R5000 is 4x. I have tried this with an R5000SC-180 MHz. Module, and at first thought it was successful. The Indy booted Irix, and seemed to run just fine. hinv reported IP24 200 MHz. R5000. But opening a few windows, with very CPU intensive tasks, yielded surprising results. The windows would just close, with no messages in the console, SYSLOG, or X11 logfiles. Very strange.

Updated 11/16/99. A bit more on overclocking an Indy R5000. I tried it again with a 3.3V SMT (surface mount technology) 50 MHz. clock oscillator. This configuration appears to work just fine, and has been running for over 3 months with no crashes or problems whatsoever. It is a bit tricky soldering the SMT oscillator, and unless you are very experienced with soldering very small surface mount parts onto multilayer circuit boards, should probably not be attempted. But, if you can find a 3.3V SMT oscillator at 50 Mhz, and want to replace the 45 MHz. oscillator on your R5000SC-180MHz. module, it looks like it works just fine. But, this will pretty much void any warranty or service contract you may have.

The module also contains optional cache (level 2) RAM. There is no way to add cache RAM, other than replacing the entire CPU module, or (on some modules) soldering Surface Mount Technology RAM chips to the board, and upgrading the 93C56 serial EEPROM that holds the CPU startup configuration. The EEPROM holds the first 128 bytes of data, and is clocked in a bit at a time serially, by the CPU on startup. It holds information such as the secondary cache RAM size, clock multiplier, etc.

CPU modules available from SGI included:

  • R4000PC-100 Primary cache only.
  • R4000SC-100 MHz. (1 Mbytes secondary cache)
  • R4400SC-100, 150, 175, 200 MHz. (1 Mbytes secondary cache)
  • R4600PC-100, 133 MHz. Primary cache only.
  • R4600SC-133 MHz. (512 Kbytes secondary cache)
  • R5000PC-150 MHz. Primary cache only.
  • R5000SC-150, 180 MHz. (512 Kbytes secondary cache)

The 4x00 series CPUs are 5V devices, and get very hot. The R4x00 CPUs will have a huge "porcupine" heat sink on the CPU chip itself, for heat dissipation. The MIPS R4600 CPU was redesigned using a smaller geometry, and a 3.3 V process, which means much less heat dissipation. The 4400-175, and 200 MHz. also use the 3.3V process, but still have a porcupine heatsink. The R4600 CPUs have a much smaller heat sink, no bigger than the ceramic PGA package, and about .3" tall. The R5000 CPU family also is a 3.3V process. SGI produced some modules with just a heatsink on the CPU itself, and other modules with a fan/heatsink combination. Also, some R5000 modules had a 5V / 3.3V DC-DC converter on the CPU module, and some did not. Not sure of the details on this yet.

The best place to get benchmark information is Ian Mapleson's SGI Advice and Technical Data web site, an absolutely phenomenal source of information.


The IP24 motherboard has 2 banks (of 4 SIMMs each). The bank closest to the power supply must be filled first. RAM must be installed in sets of 4 SIMMs. 72 pin, true parity, 70 or 60 nS, gold lead RAM must be used in the Indy. Most PeeCee RAM has tin leads, and this will allegedly oxidize with the gold leads of the SIMM sockets in the Indy, over time. EDO RAM, or non parity (x32) RAM will not work. The correct RAM will sometimes be sold as "2x36" (8 meg SIMM), "4x36" (16 Meg SIMM), or "8x36" (32 Meg SIMM). The maximum amount of RAM you can install in an Indy is 256 Megabytes (8 pieces - 2 banks - of 32 meg SIMMs).


The NVRAM chip, designated U74, at the front of the board nearest the DC power cable for the internal SCSI devices, is the soul of the machine. It is a Dallas DS1386-8K non volatile RAM, with built in real time clock. It is a 32 pin DIP chip, about 2" long, and is in a socket. It holds various system environment variables. It also holds the media access control (MAC) level Ethernet address, (man arp for details) which SGI uses as the serial number. This is a 48 bit (6 byte) number, whose first 3 bytes will always be 0800:69. This number is "owned" by SGI, no one else can use these first 3 bytes of a MAC level Ethernet address. Storing such an important number in battery backed RAM, with no way to "recover" or re initialize the address is something that has caused a great deal of hardship on SGI users who have had the misfortune of having the battery backed RAM fail, or a software overwrite of the NVRAM chip. This results in the Ethernet address being all FFs, and essentially renders your machine useless. If you lose the contents of this chip, and your machine is not under support, SGI will not even talk to you. Very few companies have the capability of reprogramming this chip.

From the prom monitor, you can read the contents of the NVRAM chip with the command printenv. You can change the contents of most of the locations with the command setenv from the PROM monitor. Once Irix is up and running, nvram will allow you to inspect and change the contents of the NVRAM chip. You can't change the ethernet MAC level address (eaddr), of course. A resetenv will reset the contents of the NVRAM chip to factory defaults. The IP address setting in NVRAM is used for booting over the network or installing software, and is not used by Irix.

Updated 18 Nov. 2001: See this file for information on how to program a new or replacement NVRAM's ethernet MAC level address. You might also try this if you get the dreaded "ffffffff" ethernet address message on startup. This method is done from the PROM monitor level, hit ESC key after power up, when the console message says "Hit ESC for system maintenance". Option 5 will take you to the Indy's PROM monitor.

The PROM Password jumper.

The NVRAM also contains a mechanism to enable a PROM password. When the ESC key is pressed after power up for system maintenance, if the PROM password has been set, you will be prompted for this password to get into the PROM menu. To disable the PROM password, remove the LBJ (Little Black Jumper) from the motherboard, close to the CPU module. Power the unit up, hit the ESC key for system maintenance when prompted, and you will see the message "PROM password jumper missing - not enforcing PROM password" or similar. Hit option 5 to go to the PROM monitor, and type resetpw - this will disable the PROM password. Power down, put the LBJ back on the two jumper pins, and power up again. When you hit the ESC key for system maintenance, you will no longer be prompted to enter the passwd.

Mouse & keyboard

Indy mouse and keyboard are PS/2 compatible. The bottom 6 pin keyed MiniDIN connector is for the keyboard, the top one is for the mouse. Unlike the O2, the keyboard and mouse ports on the Indy are not interchangeable. A Microsoft Natural Keyboard seems to work fine on the Indy, although there have been reports of some minor problems. Any PS/2 compatible trackball or touchpad should work with the Indy as well.

Power supply

The original Indy power supplies were manufactured by Nidec/Power General, and are 170 watt, autoswitching 100-240 VAC, 50-60 Hz. The part number on these is 9430813. SGI later replaced the power supply with one built by Sony, which is also labeled 170 Watt. The fan in the Sony power supply does NOT normally run. It is apparently temperature controlled, but I've never seen one run. The Nidec power supply fans spin whenever power is on. There are 4 momentary contact push buttons on the front of the supply, 3 of which are accessible from small plastic buttons on the front of the Indy blue plastic case. The farthest left button is the power button. This does not actually send a signal to the power supply. It sends a signal via a 20 pin connector that's connected to the Indy motherboard, to tell it to "wake up", and send another signal to the power supply, which turns on the power (or off as the case may be). The other 2 buttons accessible from the outside of the case are volume up/down. These also just send signals to the Indy motherboard via the 20 pin connector. The 4th button is accessible through a small hole in the front of the case, and is a reset button (cold reset).

The power supply also contains the audio amplifier and speaker (2" oval - not very high audio quality), and a bicolor LED (red/green). Normal LED sequence is green, until the boot tune is heard, and then orange (red/green on simultaneously), until the SCSI disks are ready, then green while the Indy boots. Red indicates a failure condition, or an imminent shutdown.

Replacing a power supply is extremely simple and involves removing 1 screw in the front of the power supply that connects it to the chassis, removing the 2 connectors, and sliding the entire power supply module to the rear of the machine about 1/2 inch, and then separating the power supply from the chassis. Installing a new one involves reversing the above process. Be sure to unplug the AC power cord before doing any of this. Indy power supply removal/replacement is not quite as simple as the O2, which has NO screws, just a little latch, and the connector is unplugged when you remove the entire module from the O2 chassis.

The Nidec/Power General Indy power supply (SGI P/N 9430813) is one of the most frequently failed components (along with hard disk drives and monitors), and because of the complexity of the power supply, repair shops willing to try to repair them are very hard, if not impossible to find. Swapping power supplies is probably the least expensive option.

There was a post on Usenet recently about repairing the Nidec Indy power supplies, P/N 9430813. Here is the text of that post, by Fernando Teixeira

  • 1- Check the electrolitic capacitor C1(1uF 400V) and the resistor R5, is the most frequently failure in that power supply.
  • 2- Check the diode D14 (2 diodes on a TO220 case) and D11, they fails often.

Note that there are lethal voltages present in the power supply, even if it is OFF and UNPLUGGED (the capacitors can hold a charge). Be sure you know what you're doing if you're going to try to replace components in a high voltage switching power supply.

Updated 20 Nov. 2001: Fan conversion for Sony power supplies.

Because the fan in the Indy Sony type power supplies does not normally run, dangerous heat levels can build up in the Indy chassis. The XL graphics boards get especially hot, almost too hot to touch. If you remove the top cover of the Sony power supply, you can unplug the fan connector (has red and black wire coming out of it, going to the fan). Route these wires through the plastic grommet into the Indy chassis. Either crimp or solder a drive type connector onto the 2 fan wires. If you don't mind the noise, hook up the fan (it's a 12V fan) to 12V from the drive connector. This is loud. The fan will usually spin (much slower) if you connect it to the +5V (red) lead from the drive connector. This gets rid of a LOT of heat from inside the Indy chassis. BTW, this will definitely void your warranty, and there are voltages present inside the power supply that can kill you, so do this mod at your own risk, I assume no responsibility for damages.

Graphics boards

3 different graphics options are available for the Indy. Newport or NG1 graphics (also known as XL-8 or XL-24) are available in 8 bit and 24 bit color depths. These use 2 of the GIO slots in the Indy. They have no hardware geometry engines, and no hardware Zbuffer. The geometry calculations and Zbuffer are done in software. The R5000 has an enhanced instruction set, and the graphics libraries in Irix are recompiled for the R5000, and make the XL graphics considerably faster than the same graphics board on an R4x00 series CPU (for a given clock speed). SGI marketing, in yet another effort to confuse the buying public, renamed the XL graphics to XGE in the Indys with R5000 CPUs. The XL graphics hardware is absolutely identical to the XGE. Only the name changes when the R5K CPU is used.

XZ graphics for the Indy is a 2 board set. This board set has 4 Geometry engines, and a hardware Zbuffer, making it much faster for 3D rotations, scaling, lighting, OpenGL previews, etc. The XZ graphics is slower than the XL for 2D operations, such as pixel fills, lines, etc.

When upgrading or changing from XL (XGE) to XZ graphics, you will need to re-install all the graphics portions of the IRIX operating system. It may be easier to do a complete re-install of IRIX. If upgrading from 8 bit XL to 24 bit XL (or downgrading 24 to 8), no software changes are required.

All Indy graphics boards use the "13W3" connector for connecting to the monitor. This connector is the same size as a DB-25 connector, but has only 10 pins, and 3 TNC coaxial connectors for red, green with composite sync, and blue signals. 13W3 pinout is as follows:


A1 - Red 
A2 - Green (with Composite H+V sync) 
A3 - Blue 
1 - Monitor ID 3 (XZ = Reserved) 
2 - Monitor ID0 
3 - Reserved (Composite H+V sync, - polarity) 
4 - Reserved (Horizontal sync, - polarity) 
5 - Reserved (Vertical sync, - polarity) 
6 - Monitor ID 1 
7 - Monitor ID 2 
8 - Ground 
9 - Ground 
10 - Ground

Dual head graphics option

SGI marketing literature reveals an option for a dual head (2 graphics boards, 2 monitors) Indy. Several people have tried to get this configuration going, using 2 stock Indy XL graphics board, in both 8 bit, 24 bit, and mixed 8/24 bit modes. We have tried it with the latest revision of the graphics boards, and the latest Indy boot EPROM, version 11. It has never worked. I received an email from Alexis Cousein of SGI in Belgium, stating that the dual head option REQUIRES a different version of the graphics board, for the second head, that has the GIO-32 connectors in a different physical location on the graphics board. This explains why we weren't able to get it to work, and the possibility of finding one of these special version dual head graphics boards on the used market is practically nonexistant.

Harry Goldsholl was kind enough to donate an ACTUAL dual head board for pictures. This board sits between the motherboard and a regular 8 or 24 bit XL graphics board, so you can attach 2 monitors. The board in the picture is an 8 bit board, but there was apparently also a 24 bit model.

Video input

The Indy motherboard has built in video input, called Vino. It has a connection for a digital camera called the Indycam. These are extremely low quality (i.e. cheap) CCD cameras, and are not much good for anything except perhaps videoconferencing. They seem to be optimized for flourescent lighting typically found in the office environment. Anything else will look horrible. Outdoor pictures in bright sunlight will be WAY overexposed, unless you crank down the electronic shutter speed to 1/1000 second. This will render non bright sunlight too dark. There is no way to electronically vary the shutter speed depending on the amount of light coming in.

The Vino video input also has composite (RCA female jack) input, and Svideo (miniDIN) input. If you hook up a decent video signal to either of these inputs, the quality is pretty good. Not professional by any stretch of the imagination, but acceptable, and tremendously better than the Indycam input.

The Indy has no video output standard. To get that requires the Indy Video option, which requires a GIO-32 slot (2 slots with the optional Cosmo Compress video compression board).

Disk Drives

The Indy has 1 narrow SCSI-2 bus, which serves both 2 internal drives (more on those later), and the external SCSI-2 connector. The internal 50 pin ribbon cable is terminated on the end, so internal drives in the Indy should not be terminated. There are room for 2 1" tall (sometimes referred to as "third height") 3.5" disk drives. SGI also supplied an Insite 21 megabyte floptical drive for the upper 1" tall drive bay. The media for these flopticals is pretty much impossible to get, and they haven't made the drives for years. The floptical drive also reads and writes regular 3.5" diskettes, and IRIX can mount and read/write both Macintosh and PC formats. The floptical drives must have a motorized eject, as there is no eject button accessible from the outside of the Indy case (except for the emergency hole through which you insert a paperclip to eject the diskette manually).

The lower internal 1" tall drive bay is where the system disk typically resides. These are narrow, 50 pin fast SCSI-2 drives. Because of marginal cooling, these drives should be limited to 5400 RPM drives, although many people successfully run 1 7200 RPM drive in the lower bay. If you have 2 disk drives in the Indy, you should definitely limit both drives to 5400 RPM.

The Indy motherboard SCSI controller is set for SCSI ID "0", and the system disk is typically set for SCSI ID 1. A second hard disk would typically be SCSI ID 2. The CDROM drive convention is SCSI ID 6, and a tape drive is typically set at ID 4. An internal floptical drive is typically set for SCSI ID 3. These are just convention, and any device can be set to any SCSI ID except 0. In the O2, the built in CDROM drive is set to SCSI ID 4, for some reason.

CDROM drives

Lots of SCSI CDROM drives will work to boot an Indy. Toshibas are supplied by SGI, and most of the Toshibas will work, unless they have some oddball firmware in them that doesn't allow the block size to be changed to 512 bytes/block. Other people have reported that the Plextor drives work fine as well.

External SCSI devices should be terminated at the end of the SCSI chain. If no external SCSI devices are present, terminate the SCSI-2 connector on the back of the Indy.

Partitioning a new disk and installing IRIX

The program "fx" is used to partition a new SCSI disk for use. You will need a bootable CDROM drive and a copy of IRIX. This document will describe IRIX 6.2, though other versions of Irix would be similar. Assume SCSI ID 1 for the new system disk, and SCSI ID 6 for the CDROM drive. From power up, hit the "ESC" key when you see the message "Hit ESC for system maintenance". Option 5 will take you to the PROM monitor. From the PROM monitor, type:

boot -f dksc(0,6,8)sashARCS 
boot -f dksc(0,6,7)stand/fx.ARCS --x 

Or, if you want to save a few keystrokes, these 2 commands can be combined, as such:

boot -f dksc(0,6,8)sashARCS dksc(0,6,7)stand/fx.ARCS --x 

This will load sash, the "stand alone shell" from partition 8 of the CDROM and then load "fx" the disk partitioner/formatter, from partition 7, in the directory "stand".

Answer the 3 questions by hitting return.

You should never need to format a SCSI disk drive. With Irix 6.2, the A)uto command will simply exercise the disk. With Irix 5.3, the A)uto command also low level formats the disk drive. Do not use A)uto with Irix 5.3. With 6.2, use the A)uto function, answer the questions by hitting return. When the disk exercise gets about 100 blocks into the exercise, hit Ctrl-C to stop. Hit L)abel, C)reate A)ll. To create the SGI label on the disk. .. will get you back one menu, where you can SY)nc the disk to write the changes. .. to go back one, then EXI)t to exit the fx program. Option 2 will allow you to install the system software, and ask if you want to make a new file system on the hard disks. The default for Irix 6.2 is an xfs file system, and 512 bytes per block (for 4 Gig or less disks).

(Updated for Irix 6.5.x)

You will need the following 5 disks for a default install of 6.5.x:

  • Install Tools / Overlays 1/2
  • Foundation 1
  • Foundation 2
  • Overlays 2/2
  • Applications xx/yy (where xx = month, yy = year)

With the Inst. tools disk inserted, boot the Indy into the PROM monitor as described above. The procedure listed above can be used to exercise/partition the disk as a root/usr disk. Be sure to sync, and then exit back to the prom monitor. Option 2 will "Install System Software". It will ask you if you want F)eature or M)aintenance stream (see SGI website for details - usually Feature is used for a workstation). When the first disk is loaded, you will get a message that "This CD is part of a set... etc...", so insert the second disk, and let that load, continue until you have loaded all five disks. Type done. Use the following procedure to address all the conflicts:

keep *
inst standard 
inst prereqs (ignore the warning)
keep incompleteoverlays

at this point, typing conf should show no conflicts. Type go, and get ready to start swapping disks. You will get an error about appletalk somewhere after you insert the second disk requested. Type option 3 (continue), and it should continue with no errors. When you have finished inserting all 5 disks, and it thinks it's done, type q for quit, and be prepared to WAIT for dozens of minutes while it does the rqsall. It will then ask if you want to reboot, type Y, and the machine should reboot with 6.5.x installed.


Here is where the faq is sorely lacking. An Indy can put out 2 video resolutions, 1024x768 or 1280x1024, at several different vertical frequencies. When the Indy boots, it always starts out at 60 Hz. vertical frequency, unless you're using Irix 6.5, which sets the resolution and frequency on startup. To change the resolution and vertical frequency, as root, use /usr/gfx/setmon aaaaxbbbb_ccHZ according to the following table:

H Res.	V Res.	Vert Refresh Freq.

aaaa    bbbb    cc

1024	768	60

1024	768	70

1280	1024	50

1280	1024	60

1280	1024	72

1280	1024	76

e.g. To set a resolution of 1280 x 1024 pixels at 76 Hz. vertical refresh:

/usr/gfx/setmon 1280x1024_76HZ 

There are other possible frequencies that the Indy can put out, for a complete list, see the files in /usr/gfx/ucode/NG1/vof

IRIX 6.5 saves the resolution so that on powerup, the resolution comes up to what you've previously saved it as. With Irix 5.3-6.2, you will need to add a script in /etc/rc2.d to use the setmon command. Monty Walls has come up with the following allowing the Indy to retain its monitor setup across reboots. Developed and tested under IRIX 5.3, just put your resolution commands in /var/X11/Xsgi.res

--- oxdm        Mon Apr  8 18:23:33 2002
+++ xdm Wed Apr 10 11:44:04 2002
@@ -14,6 +14,14 @@
        if test -x $XDM; then
                if $IS_ON windowsystem && test -x $XSGI || $IS_ON xdm; then
+                       # now the fun part starts of hacking Indy's resolution
+                       if [ -f /var/X11/Xsgi.res ]; then
+                               r=`cat /var/X11/Xsgi.res`
+                               $XSGI & 
+                               p=$!
+                               env DISPLAY=:0.0 /usr/gfx/setmon $r
+                               kill $p
+                       fi
                        exec $XDM

The Indy mixes together the horizontal and vertical video sync signals with the green line. This is referred to as "composite (H+V) sync on green". (Updated 2/28/01). The Indy also puts out separate sync signals, as well as composite (H+V) sync on a separate pin. The signals are as follows:

  • 3 - Composite (H+V) sync, negative polarity.
  • 4 - Horizontal sync, negative polarity.
  • 5 - Vertical sync, negative polarity.

The pinout is listed above. PC graphics boards also put out separate horizontal and vertical sync on 2 separate pins in their HD15 connectors. Sun workstations put out "Separate composite (H+V) sync", which has the H and V sync mixed together on a separate pin. A VERY Faq is "can I use my PC monitor on my Indy". The answer is a definite "maybe". First of all, you will need an adapter to convert the 13W3 connector on the back of the Indy to what's called "HD15" for your PC monitor. This will give you the physical connection.

Secondly, the adapter you purchase must be wired to provide the H and V sync signals to the female HD15 connector OR your monitor must be able to support composite (H+V) sync on green. Most inexpensive PC monitors don't. Most of the better quality monitors (e.g. Sony), do. The 13W3(male)-HD15(female) adapters sold by Reputable Systems do NOT have the correct wiring for the H and V signals to the HD15 connector, therefore, your monitor must support sync on green.

Monitors verified to work on an Indy, with the 13W3 - HD15 adapter sold by Reputable Systems: (please email with others)

  • Sun (Sony) GDM17E10 (with 13W3 connector)
  • Sun (Sony) GDM20E20 (with 13W3 connector)
  • SGI (Sony) GDM20E21
  • Sony CPD-200ES
  • Sony 210GS
  • Sony Multiscan 200sx
  • Sony CPD-17SF (1280x1024_60Hz Max)
  • Sony GDM400PS
  • Sony E200
  • Sony 100sf (need to remove pin 10 from 13W3 side of adapter)
  • Sony HMD A200
  • Dell Ultrascan 17TX (model 1726T-HS)
  • Dell D1226H
  • Philips/Magnavox CM5800
  • Viewsonic 17G
  • Viewsonic PF790 (need to remove pin 10 from 13W3 side of adapter)
  • Viewsonic PS790
  • Optiquest V95
  • Nanao Flexscan F550i-W
  • Eizo Flexscan FX-D7
  • Eizo Flexscan F-55s
  • NEC 5FG (May not work - have conflicting reports from the field)
  • NEC A900
  • Iyama Vision Master Pro 450 (S901HT)
  • Mag MX17 (using the BNCs and not the HD15)
  • CTX 1569S (with pin 10 of adapter broken off)
  • Samsung GL17si (connect monitor after Indy power up)

Monitors known NOT to work on an Indy, with the 13W3 - HD15 adapter:

  • Mag DX1795
  • CTX 700
  • CTX 710S
  • NEC 3FGe
  • NEC 5FGe (May work - have conflicting reports from the field)
  • NEC XV17+
  • Sony 100sx (15")
  • Compaq V400 (14")
  • Hitachi Superscan 600 (17")
  • Daytek DT-1726D
  • Hunglo Champ series VGA
  • NeXT 4006

On some monitors, such as the Viewsonic, I had to break off one of the pins on the 13W3 side of the 13W3-HD15 adapter. This pin (10) is used by Sun framebuffers as composite (H+V) sync ground. It is connected to the HSYNC pin on the female HD15 connector. The Indy has this pin tied to ground. Turns out the the Viewsonic was "sensing" this pin was not floating, and was not using the sync on green because of this. Break off this pin (on the 13W3 side of the adapter), and that line (HSYNC on the HD15) is floating, and the monitor works fine.

Using an SGI Monitor on a PC

This is somewhat beyond the intent of this document, but another very Faq is: Can I use an SGI monitor on a PC? The answer is a definite "maybe". First of all, see the SGI Monitor Database to see if your SGI monitor will support the resolution you're intending to use. Some of the older monitors require composite (H+V) sync on green. The GDM17E11 and GDM20D11, and older models HL7965KWSG and CM2086A3SG are of this type. Most of SGI's newer monitors are true multisync, and can support separate H and V sync signals. The GDM17E21 and GDM20E21 are examples of this. If your monitor requires sync on green, you still may get it to work, but ONLY if your PC video card can output composite (H+V) sync on green or you use an adapter to combine the separate H and V sync signals to the sync on green required by the SGI monitor. I recently bought 2 "SG1" adapters from Software Integrators. These are HD15 male to HD15 female, small adapters that work with SGI monitors that require sync on green (works on GDM17E11 and on SOME - but not all - GDM20D11s), for use with a PC video card. These monitors are true multisync. If you go this route, you will also need a 13W3 to HD15 cable for the monitor.

A. Melendez posted to Usenet that the separate H and V sync signals are present on the PC board of the GDM17E11, and you could solder some wires to an HD15 connector and bring it out the back, and it would then work with all PC video cards. Here is the text of that Usenet article:

For all of you who believe that the SGI GDM-17E11 will not work in DOS
mode or that it'll only sync-on-green, I have to disagree. I'm using
such a display with a SVGA PC after a simple mod I developed. I have
attached the instructions to this post for the benefit of all
interested. You know nobody wants you to have the schematics for this
monitor. Everybody knows it's a Sony. Yet Sony denies it at won't
provide schematics because they say it's made by SGI. And, schematics
from SGI? I don't think so. So, alas, (sigh) here's how you get it done.


I hate to burst the vendor's bubble but the FACT is the GDM-17E11 *WILL*
sync on a 31.5kHz hsync! AND it *WILL* accept discrete hsync and vsync
lines in addition to sync-on-green. I know because I'm writing this
message on this very monitor with a PC and a Diamond Stealth 3D 2000/2MB
RAM. I've used it in every mode the card is capable of. All you have to
do is:

1> Build a cable with a male HD15 SVGA conn on one end and a male 13W3
on the other. (More on this in a minute).

2> Open your GDM-17E11 monitor and follow the 3 black coax cables from
the female 13W3 to the RF shielded box mounted on the end of the picture
tube.  These three (RGB) cables solder right onto the board.

3> Look below these 3 cables and you'll see a little (orange) 3 pin male
connector that's not connected to anything.

4> Guess what those 3 pins are? The top one is vsync the middle one is
ground and the bottom one is csync (but you can plug hsync here with no
problem). (BTW, the pinouts are labeled right on the silk-screen so you
can see for yourself. I recommend you check, don't take my word for it).

5> The object of the game is to connect the hsync line from your vga
card to the csync line on this orange plug.  Plug the vsync line from
your vga card to vsync on the orange plug.

6> The pinouts for the cable are as follows:

    HD15               13W3
    1-RED    -------> A1-RED
    2-GREEN  -------> A2-GREEN
    3-BLUE   -------> A3-BLUE
    4-GND    -------> 8 -GND
    5-GND    -------> 9 -GND
    6-GND    -------> 10-GND
    7-GND    n/c
    8-GND    n/c
    9-n/c    n/c
   10-GND    n/c
   11-GND    n/c
   12-n/c    n/c
   13-HSync  -------> 3-CSync
   14-VSync  -------> 5-VSync
   15-n/c    n/c

7> *IMPORTANT*... none of this will work unless you make a 3-wire
connection from the female 13W3 connector on the back of your 17E11 to
that little orange connector you found. You need to solder some (26
gauge) wire from the respective pins to their respective places (I think
you've caught on to the pattern now). Pin 5 (VSync) on the 13W3 goes to
the top pin, pin 3 (CSync) to the bottom pin and a GND (say, pin 8) to
the middle pin. If you have the appropriate connectors go for it... or
use a CD-ROM audio cable (just not longer than it has to be). Check out
that service connector while you're at it (bottom right of rear of
monitor, and yes, it's a real RS232 port). It has a pair of 3 pin
connectors with a 75 ohm terminator switch. You can go there first if
you plan to use the monitor back and forth with PC and SGI. Put the
switch in the bottom position. This is so the new cable you soldered
won't act like an antenna when you use the SGI because it won't be
connected to anything (the SGI uses sync-on-green, remember?)

8> If you can't find the 13W3 connector for your cable (then don't try
this project! Sheesh! [just kidding]) you might as well mount a female
HD15 on the back of the monitor as save the $70+ for having the cable
made. Then you can use a regular vga cable.

OK, now for the disclaimer. The above mod WILL void your monitor
warranty so be warned. Also, I accept no responsibility if you get hurt
or destroy any equipment as a result of making this mod. I've only
provided this information AS IS and make no guarantees expressed or
implied whatsoever. If you've never solder before or aren't real keen to
electronics.. forget this project. And if you can't find a 13W3
connector that tells me you're not anything near an electrical engineer
and should also forget this project.

My PC never looked so sharp! AND in DOS mode!

Best regards,
A. Melendez

angel <at> magicnet <dot> net

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