Serial and printer interface for the FX-602P calculator

This device attempts to emulate the original FA-2 cassette interface and the FP-10 printer. Files are transferred through the serial port instead of the tape. It's based on the FX-700P mass storage and printer interface with software version 27, and uses the same data format.

An optional parallel printer port board can be connected to the I2C bus. All known FX-602P and FX-702P printing modes are supported.

The device was tested with the FX-602P and FX-702P calculators.

Hardware

schematic of the FX-602P interface

The jumpers on the PB5 and PB6 pins can disable the tape or printer support.

Jumper on PB5	Jumper on PB6	Selected function
open	open	Both tape and printer support enabled.
open	closed	Only tape interface enabled.
closed	open	Only printer interface enabled.
closed	closed	Interface disabled.

An inserted jumper is obligatory for the FX-602P to select the destination of the SAVE command either to the file or to the printer.
The FX-702P has separate commands for file saving and printing, so both jumpers can be left open.

Software

fx702_13.zip - AVR source code