The difference of SD and non-SD model may help to add SD support to the Prizm model (hoping, that only connector + few discrete parts are missing and Prizm FW has SD supports)

Just an idea ... :-)

How do you connect to Linux?

See (for example) this:http://linuxtechres.blogspot.com/2009/09/how-to-login-from-serial-port-under.html
But please use speed 9600, it is hardcoded in this verion of the fxterm.
So you will need to add line to your inittab:
s0:2345:respawn:/sbin/agetty 9600 ttyS0 vt100
to enable serial console on COM1

The Physium add-in is very big, I think it is not copied to the RAM but the corresponding flash part is mapped to the address where add-in should start. But what happens, if the physium (or other larger file add-in) becomes fragmented ?

Is there any chance to get somthing that would be 100 times better?

Probably no, but if you have the SD version, I can offer 5.8 times better quality :-)
http://www.casiocalc.org/?showtopic=5466

Maybe on Fx*9860, too, no? PLease
Juste for terminal! :p

I was thinking about such program when I bought my fx9860G, but I found a problem with font / screen resolution. Simply the screen is too small to display moderate count of character in a row. Standard font has 5+1 pixel width => 21 characters, which is too few (the +1 is for space between letters).
Smaller font (4+1) would be hard to read and you get 25 characters.
More smaller font (3+1) would get moderate count of characters, but there are hardly distinguishable characters (such like M/N/W/H ).
I want not to use proportional font as it sucks :-)

The FXTerm is not finished (some escape sequences are ignored, so e.g. editors don't work). I can finish this after I find some spare time and then I can port it to fx9860G, but I need to solve somehow the font problem.

Do you have any idea ?

How'd you zoom so much?

I used microscope camera, zoom is ~ 200x

I found what appears to be the backup display ram for when the Prizm is in the menu and an app is paused. That location is from 0x880a2ad6 to 0x880cbd26. If you check from insight there is a screen bitmap in that block that corresponds to the currently running app. Currently I can not find any OS references to those addresses so it is not yet safe to use that space as other OS versions may use a different address

Simon already documented this memory in his super manual (part of his mini SDK):
syscall 0x1E62 : void SaveVRAM_1( void );
saves the VRAM to 0x880A2AD5; the buffer seems to be used while process-switching with the MENU-key.

And I used it in my jpeg variant of video player (I need all RAM I could find:-) )

The question is too common. It is (I think) very easy to solder wires and components with wire connection, but what about SMD ? :-)