update; Everything works as expected except that pin 7 on the cassette port is ground! so the only spare is pin 8. Use that one! I'll post something in the personal folders at club100...
On Wed, Feb 5, 2020 at 7:58 AM Stephen Adolph <twospru...@gmail.com> wrote: > I've been toying with using the cassette port to send serial data, for use > with an external device that only takes input data. Kinda the opposite of > the BCR port. > > The point being - to save the RS-232 port for bidirectional comms. > > After some experiments, I think it is quite useful. I have been able to > demonstrate an absolute maximum speed of ~100kbits/sec (which isn't all > that useful given the typical serial port speeds) and a more useful 57600 > kbits/sec. > > Quite respectable! > > To use this routine, you need to make a small change to the hardware. > There are two unused pins on the cassette port (suggest using pin 7). > Install a single lead from pin 7 to pin 12 of M34. This wire bypasses the > analog filter used by the cassette circuit, and allows the direct output of > high speed signals. > Connection to an external device needs only 2 wires from the cassette port > - ground and Tx data. > > [image: cassette hack.png] > > A demonstration routine is attached that just loops and sends the same > character out the cassette port is attached. At the core it is a very > short routine. > Comments welcome. cheers Steve > >
