[Coco] Re: CoCo bitbanger does 115200 bps !

[Torsten Dittel]

> MIDI is 31,250 b/s, or 1,000,000/32.  Works out to 57 clocks per bit  IIRC,
> at the double clock speed used in OS9-L2.  Pretty sure about the 57,  since I
> had to count cycles to write the transmit loop back in 1986.  Let's  see, 3.58
> MHz times 32 divide by 2 = 57.28, check.

I started to dive into the topic when I realized that there were
MIDI-notes "hanging" while using the bitbanger-MIDI-Out of the Lyra
program on my CoCo2. I disassembled the ML-code and found out it was
trying to send the bits in 28.5 (=57/2) cycles by sending the "0"s in 28
and the "1"s in 29 cycles. This worked only perfect in cases like $55 or
$AA. I wrote a new routine which was transmitting the first bit in 28,
the second in 29, the third in 28 cyles and so on. I later used the code
in some of my own (never released) MIDI programs until I had my selfmade
2 ACIA MIDI Pak (2x MIDI in and out)

Regards,
Torsten