2. WHAT YOU'LL NEED

Well, you'll need an SGI Indigo!
Indigo keyboard and mouse
An Indigo compatible CD-ROM drive (an external SCSI one with CN50 connectors, either a proper SGI one or a Toshiba TXM3301E1. Others might work)
IRIX installation CDs (I'm concentrating on IRIX 5.3 here, but I'm sure it applies to later versions).
VGA monitor (SGI one or any PC/Mac monitor with a standard 15 pin D-Sub)

3. PASSWORDS

There are 2 passwords that may be present on an Indigo: the root password, and the hardware PROM password. If you don't know either of these, then I'd advise you to give up now! The PROM password will allow you to boot off the CD-ROM and delete/reset the root password. Similarly, a root password will allow you to alter the PROM password (using the nvram command). On Indigo2s and Indys there's a jumper on one of the boards that allows you to reset the PROM password, but sadly the only way to do this on an Indigo involves a soldering iron! If the machine doesn't have the PROM password set, then that's even better... if you're thinking of buying one of these, check that you can get into the PROM before parting with cash (hold down Esc during power on for a menu).

4. DISK PREPARATION

Plug in your external SCSI CD-ROM, and give it a SCSI ID between 4 - 7 (I always use 6 for some reason!). Power it on and put the IRIX 5.3 install CD in.
Power on the Indigo, and push Esc when prompted for the maintenance menu.
For now, I'd advise you to reset the root password, boot normally and see what state IRIX is in, so....
Select option 2 from the menu (Install Software), and it should now prompt for a password (if there is one set), and then ask you to boot from the CD.
Once it's been through loading up the CD, you'll now get an 'Inst' menu. Choose option 11 (Admin), and then option 7, (shroot) which gives you root access.
You can now use passwd to alter the root password to something you know.
To get out and restart the system, type exit to get you back to the Admin menu. Options 17 then 12 will quit out and prompt you to restart.

5. SOFTWARE INSTALLATION

If you're bored with the current install, and want to wipe it completely follow these steps:

Boot into the PROM maintenance menu, and choose option 5 (Command Monitor).
At the prompt, type boot -f dksc(0,x,8)sashIP12 where x is the SCSI ID of your CD-ROM drive (6 in my case).
Once SASH (Stand Alone SHell) has loaded, to wipe the disk, use FX (like FDISK). Start it with dksc(0,x,7)/stand/fx.IP12 where x is the SCSI ID of your CD-ROM drive.
FX might ask you if you want to enable Extended Mode - say YES or you won't be able to erase things.
Answer the next 3 questions with the defaults (dksc,0,1).
Now (L)abel the disk , and then (C)reate (A)ll
Go back up one menu with .. and (SY)nc the filesystem
Go back up again with .. and (EXI)t confirming any changes.

The indigo will then restart and drop you at the maintenance menu.

Choose option 2 (install software) and confirm that you want to boot from the CD-ROM

At the installation menu, choose option 7 (step). If you have a really small hard disk, then only the required modules are going to fit. In step, you go through a long list line by line choosing what to install (i) or remove (r). On the line is an indication of whether that module is required [R]. Only install these required modules for now. You could also install the desktop modules, but be wary of the sizes. You can always come back later and install more things if you have the space (df will tell you disk usage).

Once you've stepped through everything, try to install by typing go. Undoubtedly there will be some conflicts. Type conflicts to see a list. To resolve them, simply type conflicts 1a 1b 2a 2b etc. Once these have all been resolved, type go again, and installation will proceed.

Once it has finished, you'll be back at the menu, so type quit and the system will save all changes and then restart. Let it boot up normally and you should arrive at a login screen.

6. CONFIGURATION

After starting for the first time, the login screen should have an EZSetup icon. Double clicking this will allow you to configure networking and some other items with a 'wizard' type interface. Note that the netmask in networking is in hexadecimal with the default being the equivalent of 255.255.255.0. Once you've restarted, you can then login as root or a user you've created and configure the look and feel of your desktop, what users are displayed on the login screen and many other things.

7. SECURITY

IRIX 5.3 is a nightmare. It comes with many services running as standard, including telnetd. I really do not recommend that you use it permanently connected to the internet unless you have a firewall and have downloaded and installed every available patch (there's going to be a lot!). R3000s can only run IRIX 5.2, but R4000s can run IRIX 6.2 which is much better. Once I have my hands on a copy, I'll do another install guide for it. Note that this guide will get you up and running.. there's an awful lot more work to do to your Indigo before it's vaguely usable.