Can Linux Be Put On The Prizm?

Was just looking around and came across this: http://wiki.debian.org/SH4

How hard would it be to make this (or any other linux distro) work on linux?

Very hard. The prizm's small amount of memory is the main factor in this. 32 MiB is not a whole lot of space to stick a distro on. At the point where there would still be enough space for programs and such, the distro would be so stripped down that it would be more effective to write a whole new OS. There are also many undocumented hardware quirks that would necessitate copying parts of the default OS without knowing what they mean. However, there are hardware problems with flashing the prizm, so even if a OS was made, it would not be practical to implement.

What abut building a driver to interface with an external USB drive, and then putting linux on the external drive?

(Just came up with that off the top of my head, so if it sounds stupid, you know why)

If you want to simulate how it would look like, you can run terminal emulator in your prizm and connect (by serial line) to some real linux machine.
See :
http://martin.poupe....term/index.html
http://www.cemetech....?t=8119&start=0
http://www.omnimaga....p?topic=9152.45

so that basically make the prizm screen a terminal, right?

Also, would it be possible to make driver for prizm to read data from an external hard drive and then make the prizm run linux from the external drive?

so that basically make the prizm screen a terminal, right?

A dumb terminal, yes.

Also, would it be possible to make driver for prizm to read data from an external hard drive and then make the prizm run linux from the external drive?

Read data, yes. Run linux, no. As stated before there are too many issues with unknown hardware to make a functioning OS.