Procedure from a Linux machine. 

Assuming the HP 2645 is connected to the linux machine on ttyS0 (COM1)

stty -F /dev/ttyS0 300 (for the menu, upload at 300 bauds or the many CRLF will knock the terminal out of the read mode)
stty -F /dev/ttyS0 2400 (for all other files)

Put tape in R tape, rewind, make sure tape light is on (do Green - Find File 1 - R. Tape if not)
Set terminal to baud rate (300 or 2400), press Remote, RECORD

Type at the linux commmand:
cat file.txt > /dev/ttyS0

After each file is done, write a File Mark to the tape:
Green - File Mark - R. Tape

Record files to tape in this order:
menu
invaders
hacman
pong
drive
maze
shoot

To play tape:
Place in Left drive, rewind
Press READ
Menu appears, press function keys as displayed to jump to game
