[Coco] CoCoNet status

[Torsten Dittel]

Darren A schrieb:

> Have you tested this with a CoCo 1?  Recent tests I've done have led
> me to the conclusion that the CoCo 1 hardware is not capable of
> transmitting 57600 bps through the bit banger port, although it can
> receive data at that speed. My guess is that the opamp used for the
> level translation to +/- 12 volts can't operate that fast.  You will
> probably have to lower the transmission speed or specify a CoCo 2 as
> the minimum requirement.

I darkly remember, when my father once tried to run the bit banger MIDI 
OUT of LYRA on his CoCo1 (first board, Serial#338), it didn't work 
(unlike my CoCo 2B). He then figured out with a scope, that single bits 
at the bit banger port (e.g. the "1" in "00001000") were "triangles" 
with lower amplitude (than the expected "rectangle" should have), 
because the slopes weren't rapid enough. He exchanged a little chip (8 
pin DIP?) by a compatible faster one (port driver? Would have to look 
that up in the schematics) and it worked! (Well, there is a mistake in 
the LYRA MIDI driver which led to some errors, but that's another story).

Regards,
Torsten