[Coco] CocoMIDI and Other Boards Available

[Jayeson Lee-Steere]

Interesting data Bill. The datasheet suggests two improved capabilities in
the 68B50. One is that the serial clock can be much higher than the 6850.
The other is that the registers support 2MHz operation (can be placed on a
2MHz bus). The former advantage should not come into play here as the
serial clock is the same super-slow speed used by MIDI. I might expect some
reliability issues accessing the regular 6850 with the Coco in high speed
mode. I can't imagine why the 68B50 would be (significantly) more suitable
for simultaneous play/record.

It is unfortunate some software runs the Coco 3 at high speed. I can't see
much reason not to slow the clock while accessing the 6850 registers - the
data rate from MIDI is rather slow and I would not expect the impact on the
application to be large.

I'll let folks know.

- Jayeson

On Fri, Aug 19, 2016 at 11:16 AM, Bill Pierce via Coco <coco at maltedmedia.com
> wrote:

>
>  Jayeson, to elaborate on your assumpsion of the 89mhz and 2mhz MIDI
> operations on the Coco 3, the "Lyra" midi sequencer by Lester hands ran in
> 89mhz as it was originally conceaved on the Coco 2 in 8 channels. In later
> revisions, Lester did speed up operations to 2mhz for the Coco 3 therefore
> speeding up screen refreshes, but reset the speed back to 89mhz while
> accessing the midi ports as it kept him from rewriting the delay loops for
> the proper baud. Later, he released the CocoMidi series (2, 3, & pro) which
> were written for the Coco 3 and used the 2mhz speed as they were live midi
> recording programs as well as sequencers with 16 channels, but a text
> display. I never had the chance to run Cocomidi pro so I'm not sure if it
> could do reads/writes simultainiously. Mike Knudsen's OS9 sequencer
> "Ulitmuse3" ran at 2mhz at all times with 16 channels and was written from
> the ground up for 2mhz as OS9 L2 always runs in 2mhz. Mike also wrote an
> unreleased Midi recording program under OS9 that used 2mhz as it took all
> the Coco had to keep up with incoming data. In his notes that I've read, he
> stated if he had the faster UART, there was a possibilty of simultainious
> play/record and interrupt based operation. A few of the midi people on
> Delphi & CIS had changed their paks to the faster UART and reported much
> more reliable speed in playback.
> So I would assume the main difference in the 2 UARTs would be the
> possibility of simultainious record/playback with the faster UART. In the
> old days, I actually used the bitbanger for midi as I couldn't ever afford
> the midipak. The bitbanger midi was pretty reliable for just playback, but
> I doubt very seriously it could handle recording, but who knows... with dw4
> runnin at 115k & 230k through the bitbanger (and doing midi!), it may be
> possible, but not in both directions at once. I have had a Glenside pak
> since about 2011 and I have no problems with playback with any of the Coco
> midi software :-)
>
>
>
>
> Bill Pierce
> "Charlie stole the handle, and the train it won't stop going, no way to
> slow down!" - Ian Anderson - Jethro Tull
>
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>
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