missing 4D/35 audio interface

[Mark Callow]

In article <9104181042.AA17537 at crow.omni.co>, dgordon at crow.UUCP (Dave Gordon) writes:
|> 
|> received.  Would someone from SGI be willing to comment on when the audio
|> kit is likely to be available?
|> 
Engineers and dates are like oil and water; they don't mix.  However...

you should have it by late summer.

|> Incidentally, does anyone know if it's possible to use the 4D/35 serial
|> ports to interface to a MIDI device?  In particular, I'd like to be
|> able to use the MIDI baud rate of 31.25K (since devices to match RS232 
|> electrical signals to MIDI are widely available).  There's a "reserved"
|> pin on the DIN connector.  Any chance that might turn into an external
|> clock some day?   Alternatively, is there a commercially available box
|> that does baud rate conversion?
|> 

The serial ports with the DIN connectors are intended to support MIDI.
We designed them so that you can use the same type of MIDI interface box on
the 4D/35 as you use on a Macintosh.  We discovered the day before the
4D/35's started rolling off the line that a certain popular Macintosh
MIDI interface didn't work with the 4D/35.  We tracked it down to the
a difference in electrical characteristics between the RS422 driver chip
we were using and that in the Macintosh.  This popular MIDI interface
relied on the particular characteristics of the Macintosh RS422 interface
to save money by eliminating the -5v supply normally needed.

We are now using the same part as the Macintosh.  An ECO will be available
shortly for those who need to have early systems updated.

The driver that lets you operate these ports in MIDI mode will be released
later, probably with the audio upgrade kit.

-- 
>From the TARDIS of Mark Callow (aka Captain Multi-Media)
msc at ramoth.sgi.com, ...{ames,decwrl}!sgi!msc
"Spirits of genius are always opposed by mediocre minds" - Albert Einstein