This CP/M solution is going to be absolutely amazing! Is someone planning to show this at Tandy Assembly? I wasn't planning to have a table this year, but if this is going to happen before September, I might want to change my mind and plan to demo this sucker!
-Josh On Wed, Feb 5, 2020 at 3:28 PM Philip Avery <pav...@xtra.co.nz> wrote: > Very cool Steve. For M100 CP/M we can use this for external 80x24 video > keeping the RS-232 port free for TPDD which is used for migrating files > from the net. > > Philip > > On 6/02/2020 1:58 am, Stephen Adolph 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 > > >
