While e.g. Cisco 1812 routers manage loading an IOS image requiring twice (256 MB) the amount of RAM they have (128 MB) quite well, it isn’t always that nice. A Cisco SOHO 91, for example, couldn’t cope with it.
A 12.4T series IOS image started to boot correctly, but just before displaying the beloved
Press RETURN to get started! message, it started flooding the console with messages about the image needing more RAM than the router actually has. There would be nothing wrong about it if not the thing that popped up a moment later:
*** System received a Software forced crash *** signal= 0×17, code= 0×5, context= 0×0 PC = 0×800080d4, Cause = 0×20, Status Reg = 0×3041f003
(Ok, I admit. I didn’t copy that message from the console. I stole it from here :D Maybe one time, when I find inspiration, I’ll restore this situation ;))
In those circumstances there was not much more left to do but to press
CTRL+Break during bootup and load a 12.3T series IOS image from ROM monitor mode :(