🚀 go-pugleaf

In article <229@obie.UUCP> wes@obie.UUCP (Barnacle Wes) writes:
>
>Consider this little GEM :-) gleaned from the Abacus "Atari ST Internals"
>book:
>
>Bits 0 and 1 of the Control Register on the MIDI 6850 chip control a
>"divider" for the input clock, determining the baud rate.  The MIDI sets
>these bits to 01, meaning divide the clock signal by 16.  The clock to
>the 6850 is 500 Khz, which gives us the MIDI speed of 31250 bps.
>
>If you reprogram these bits with 00, it tells the chip not to divide the
>clock, giving you a clock of 500 Khz, which is adequate for a simple,
>small network (like AppleTalk).
>

i thought appletalk ran more like 110 Khz? anyway, the midi init routine
is on page 29 of usa.s in your developer's documentation -- you can buy
used copies for cheap if you can find disgruntled developers :-)

it says : /16 clock, 8 bit, 1 stop no parity rts low, no transmit
interrupt, receive interrupt.

i guess you'd eventually want to turn on the transmit interrupt and
replace the bios routine which handles those interrupts, so that you
could buffer in and out.

it's too bad that that acia doesn't support /4 clock. but maybe /16
will work? if i had 2 st's i'd try it.

-- greg

----------
Greg Lindahl                                     internet:  gl8f@virginia.edu
University of Virginia Department of Astronomy     bitnet:  gl8f@virginia.bitnet
     "Doesn't Quayle know that the FBI handles domestic assassinations?"