It isn't the CPU that has a problem, it's the expansion bus.  ISA BIOS 
couldn't deal with mapped I/O addresses above 16M because of a limited 
(24 bit) addressing range (ISA was originally designed for the earliest 
PC's, and couldn't be expanded without breaking compatibility, although 
EISA tried, PCI has the same problem now with limited enhancement, hence 
the PCI Express standard which uses serial connections that are easier 
to expand later).

The ISA LFB setting is, in fact, there to define the size of the memory 
address space where the video RAM will be mapped (always at the end of 
the ISA address space).  It doesn't matter, much, for the onboard video 
Mikey has, he just needs to set it correctly according to his 
Motherboard documentation, the BIOS defaults are probably correct in 
this case, if he doesn't have the documentation.  During debugging, you 
can always set it to the lowest value (1M), since the only side effect 
of this is that the system won't take full advantage of the frame 
buffer, but it will still work.

I don't know Mikey's exact problem getting Ubuntu working, but I doubt 
it's related to this setting.

Mikey,  If you really want to know if the BIOS settings are the problem, 
try running a Puppy Linux CD, if that runs, then it's not BIOS settings, 
it's a case of the system being too outdated for Ubuntu to handle, and 
you'll just have to run a different distro.

FoulDragon@aol.com wrote:

> If it were a problem, I think it would show by only reporting 15Mb (or 
> less) memory in the Linux boot details when it has more installed.
>  
> ISTR it doesn't cope well (or didn't in the olden days) with a hole.
>  
> Considering most 586 systems were expandable well over 16Mb, I'd be 
> very amazed if there isn't a way to point the video memory outside the 
> lower 16.