Well, if we are going to go back to prehistorical times...

TI-53, TI-57, TI-58C, Casio FX702P, Sharp PC-1250, Canon X-07, HP-41CV, Atari Portfolio (the one you see in the terminator 2 movie...), HP-48SX, HP-95LX, HP100LX, HP-200LX (I love those), HP48GX, HP Omnigo (junk), HP Omnibook (more a sub-laptop than a pocket computer), HP-48G, Olivetti quaderno (not used that much, a buying mistake), Toshiba Libretto 50CT (*), Palmpilot, Palm V, Garmin iQue, Sharp Zaurus SL-5500, Sharp Zaurus SL-C700 (*), Sharp Zaurus SL-C760 (*), Nokia 770, Nokia 6630, Nokia N80 (upgraded to Internet Edition), Nokia N800, HP-50G, Nokia N810, Nokia E51.

(*) imported from Japan.