Hi,
I also have this laptop. But in a 12mb config.
There are linux distributions designed for such small
machines. One good is Tiny linux. But it is based on an old
kernel.
http://tiny.seul.org/
There is still one chance to have an uptodate system.
Just use NetBSD. If you have a -reasonable- PC to host
a kernel compilation, just go and cut one down to the needs
of your NCR 3150. I made it on the laptop, it tool ~20 hrs
to get compiled, but I had a 800k kernel at the end. And
NetBSD shall be faster than linux.
If you by an additional 8mb RAM, ou will be able to install
Xfree and play with icewm for example !
What I'am now experimenting on my NCR 3150 is he usage
of Compact flash cards. I wanted to use it as an installation
medium, but the NetBSD kernel seems to have timeouts on
it...
Good hack !