[comp.sys.dec] Max baud rate on DS3100 serial line.

stpierre@swan.ulowell.edu (Pete St Pierre) (07/04/89)

	We have a research project here that requires a workstation (currently
a Sun 3/50) to write to a serial<->midi interface at 38.4Kb.  The Sun handles 
this fine, but in moving to a DS3100 platform, we can't get speeds above 
9.6Kb.  The header files support 19.2Kb and 38.4Kb, but it seems the DS3100
hardware doesn't.  My questions are: Is this a known hardware limitation?  Are 
there any other DEC workstations that support >= 19.2Kb?  Thanks...
				...Pete

-- 
Bob (Pete) St.Pierre    	                           University of Lowell
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stpierre@ulowell.edu                                       Lowell, Mass 01854
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awpsys@ultb.UUCP (Andrew W. Potter) (07/05/89)

Serial to midi interface?   Where can one get such a beast?

- Andy

-- 
Andrew W. Potter                 Bitnet:   awpsys@ritvax.BITNET
Systems Programmer               Internet: awpsys%ritvax.bitnet@cunyvm.cuny.edu
Information Systems and Computing
Rochester Institute of Technology, Rochester NY, 14623 (716) 475-6994

lumsdon@tofacsa.arpa (Lumsdon) (07/18/89)

An Atari ST or Mega comes with a MIDI-RS232 inside. You can purchase
such things for Amigas for less than $200. MIDI is merely a fast
RS232 with the pins arranged into a strange looking port that
requires a matching 2 or 3 headed plug.

albaugh@dms.UUCP (Mike Albaugh) (07/18/89)

From article <593@dtix.ARPA>, by lumsdon@tofacsa.arpa (Lumsdon):
> An Atari ST or Mega comes with a MIDI-RS232 inside. You can purchase
> such things for Amigas for less than $200. MIDI is merely a fast
> RS232 with the pins arranged into a strange looking port that
> requires a matching 2 or 3 headed plug.

	I didn't see the original question, but just couldn't let this pass.
MIDI is _not_ RS-232. It is a opto-isolated current loop. It runs 31.25K bits
per second, 8 data no parity, one stop. The RS-232 to current loop conversion
should pose no real problems for the reasonably electronically adept. The
unconventional data rate could be a real problem, unless your port provides
for "external clock". The timing resolution to _use_ MIDI could be well-nigh
impossible to achieve on a multi-tasking virtual-memory computer. Not
totally impossible, but it makes the other pieces seem trivial by comparison.

	The popular MIDI boxes for the likes of the IBM PC have internal
smarts to tag commands with time-stamps and _big_ buffers, so the PC can
get around to them at its leisure.

				Mike

| Mike Albaugh (albaugh@dms.UUCP || {...decwrl!turtlevax!}weitek!dms!albaugh)
| Atari Games Corp (Arcade Games, no relation to the makers of the ST)
| 675 Sycamore Dr. Milpitas, CA 95035		voice: (408)434-1709
| The opinions expressed are my own (Boy, are they ever)