[rescue] SGI Indy questions
james at foonly.com
Sun Jan 12 11:42:20 CST 2003
On Sun, 12 Jan 2003, Jonathan C. Patschke wrote:
> On Sun, 12 Jan 2003, Curtis H. Wilbar Jr. wrote:
> > I see a 1 and 2 port (are these serial?)
> Yes. RS-422, like a Macintosh.
The Mac does not use RS-422, despite lying documentation. It uses
differential RS-423 which is compatible with RS-232/EIA-232D under
favorable conditions. It's also more or less compatible with RS-422,
under good conditions with a favorable wind and high-quality RS-422
receiver chips that won't blow out when exposed to higher-than-spec
Had Apple used RS-422, you would not be able to connect RS-232 devices.
SGI used RS-423 on the Indy.
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