RS/6000
Problem: Error 4B265400 on front LCD panel
Cause: Incorrect boot parameters in firmware

Let me preface this with the fact that I've only used AIX 4.1.5 on an Apple Network Server, and I haven't touched CHRP hardware before.

After upgrading from AIX 5.1 to 5.2 on my shiny, new-to-me 7043-260, I was bummed when it got stuck in open firmware at the line that says booting and never continued to the line that says closing stdin and stdout. The LCD panel on the front gave me a cryptic "4B265400" and the only thing Google found for me was a Chinese forum that suggested a microcode update was needed. But the big blue's website only requires a firmware update for 5.3, not 5.2. So I did a complete overwrite install but got the same error.

I resigned myself to getting the firmware update, made a floppy disk on a windows box and attempted to install it within the firmware menu. It didn't like my disk. I figured I couldn't do any more damage poking around in the menu, so I tripped over the multiboot option. Inside I found the option to select the system you want to boot. It saw my 5.2.0 install, so i selected it and hit enter. About 30 seconds later, I was presented with the installer-assistant and the machine thereafter boots and reboots correctly. It seems that this error is a matter of incorrect boot parameters being stored in firmware.

My new toy:
43p-260
2x 200 Mhz PowerPC 630/Power3
4MB L2 cache per processor
4GB of RAM on one memory card
2x 9GB hard drives
CD-ROM
DDS3 tape drive
1x Gigabit Ethernet PCI card, optical
1x GXT130P <- yuck, i need a GXT3000P to play quake 2

Came with a full set of 5.2 install media, User and install manuals, a SCSI adapter cable.