Danjovic has managed to write a bitbanged serial routine which is able to transmit data to a PC at speeds of up to 19200bps. In order to accomplish this a TTL to RS232 level shifter is needed, implemented using a transistor.
Using a small program it is possible to intercept the LPRINT hook used by MSX-BASIC to direct output to the serial port. The example program in BASIC can use the LLIST command to send the listing itself to a PC running a terminal program such as HyperTerminal. Timing values can be easily adjusted to best suit the MSX computer used and to change the transmission speed from 1200 to 19200 bits per second.
The data goes out through pin 6 of Joystick Port B. The source code as well as the schematics of the 1-transistor TTL-to-RS232 level converter can be found on the author's
weblog.
Relevant Link:
TTL to RS232 Converter
Relevant Link:
LPRINT to Joystick Port
