The Epson P-40 is compact portable uni-directional thermal dot matrix printer which operates on NiCd batteries. It features various print modes including two bit image modes and character sets for 9 countries. It also has the ASCII 95 character set. It has a speed of 45cps for normal characters and 22.5 cps for enlarged characters.
It uses the Epson thermal roll paper (P40TRP).
The printer was available with either a parallel type with a Centronics interface (P-40P) or a serial interface with a 6-pin DIN connector (P-40S).
I have example of both parallel (P-40P) and serial (P-40S) and have used the former successfully with Psion Series 3 and 5mx using the Psion Infrared parallel interface. Getting them tow work via serail is a work in progress.