Getting 422 in and out of Your SGI - Lurker's Guide - lurkertech.com
lurkertech.com Lurker's Guide Getting 422 in and out of Your SGI

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Note: Updated Lurker's Guide available (but not this page!)

This page belongs to the old 1990s SGI Lurker's Guide. As of 2008, several of the Lurker's Guide pages have been updated for HDTV and for modern OS platforms like Windows and Mac. This particular page is not one of those, but you can see what new stuff is available here. Thanks!

Getting 422 in and out of Your SGI

By Chris Pirazzi.

You will need a serial port that talks RS-422 (that spec is now officially called TIA/EIA-422-B).

SGI serial ports talk one of three electrical protocols:

  • All SGI machines have at least one RS-232 (officially, EIA/TIA-232-E) port. So you can always use a 232 to 422 converter. We strongly recommend self-powered converters rather than converters which suck power off the 232 port's flow control or data lines. Currently, SGI does not officially support any particular converter. An officially SGI-supported solution to this, which will produce a spec 422 signal, is in the works. Unofficially, we have had some luck on O2s with the port-powered B&B 422LP9R adapter at short (10ft) distances with unterminated cables. Customers have also reported luck with the Antona 6090 adapter for Mac MIDI interfaces on O2; that adapter may also work for 422 deck control. If you have had good or bad experiences with particular adapters, send us some mail and we'll include your experience here.

  • Some SGI serial ports talk 422 directly, and you're set.

  • Some SGI serial ports talk Macintosh levels. Although a Macintosh port consists of a differential RX pair and a differential TX pair like 422, the line drivers and receivers on these ports will detect and transmit the voltage levels in Apple's "Guide to the Macintosh Family Hardware," not TIA/EIA-422-B (and also not TIA/EIA-423-A, as some have asserted). Plus, TIA/EIA-422-B defines only RX-, RX+, TX-, TX+, and GND. The Macintosh spec defines three additional signals: HSKi, HSKo, and GPi. The Macintosh level SGI ports were designed to accept Macintosh LocalTalk devices and Macintosh Serial devices such as MIDI interfaces. Some customers have reported luck using these ports to drive 422 decks at short (10ft) distances with unterminated cables. Your mileage may vary.

When the serial port people saw how many pixel packings there were, (see The Pixel Rosetta Stone: Packings and Colorspaces), they got jealous. In case you're trying to roll your own conversion cables or converters, we will tell you the pinouts of all 232, 422, and Macintosh ports on all SGI machines we know about, and where we got the information from. When you see a pin with no function in the tables below, it means the pin is reserved and you must not connect it to anything.

Onyx and Challenge machines have built-in female DB9s with this 232 pinout (source: man serial(7)):

Pin232 Function
1
2TD
3RD
4RTS
5CTS
6
7GND
8DCD
9DTR

Onyx and Challenge machines have built-in female DB9s with this 422 pinout (source: man serial(7)):

Pin422 Function
1
2TX-
3RX-
4
5
6GND
7TX+
8RX+
9

On Onyx and Challenge machines, you can get the Audio Serial Option (ASO). ASO boards have six female DB9s with the same pinout as the built-in Onyx/Challenge 232 ports (source: man asoser(7)). You can switch these ports to 422 mode, where they have this 422 pinout (source: man asoser(7)):

Pin422 Function
1TX+
2TX-
3RX-
4
5
6RX+
7GND
8
9

The Octane, Onyx2, and Origin 2000's male DB9 ports have this IBM PC 232 pinout (source: man serial(7) on IRIX 6.4):

Pin232 Function
1DCD
2RD
3TD
4DTR
5GND
6
7RTS
8CTS
9

You can switch the Octane, Onyx2, and Origin 2000's male DB9 serial ports into Macintosh mode using code we will show later in this section. When you do this, their Macintosh pinout is (source: man serial(7) on IRIX 6.4):

PinMacintosh Function
1
2RX-
3TX-
4TX+
5GND
6RX+
7HSKo (defined by Apple)
8HSKi (defined by Apple)
9

Not to be outdone, the Origin 200's male DB9 serial port has a different Macintosh pinout (yes, this is a bug, it is miswired. source: upcoming SGI audio FAQ item):

PinMacintosh Function
1
2RX-
3TX-
4
5GND
6RX+
7TX+
8HSKi (defined by Apple)
9

This O200 miswiring only applies to Macintosh mode. O200 serial ports behave like O2000 and Octane for 232 mode.

The female Mini-DIN-8 connector on Indigo, Indy, and Indigo2 has this 232 pinout (source: man serial(7) on IRIX 6.4):

Pin232 Function
1DTR
2CTS
3TD
4GND
5RD
6RTS
7DCD
8GND

You can switch the Indy and Indigo2 systems into Macintosh mode using code we will show later. The Macintosh pinout of the female Mini-DIN-8 on these machines is (source: man serial(7) on IRIX 6.4):

PinMacintosh Function
1HSKo (defined by Apple)
2HSKi (defined by Apple)
3TX-
4GND
5RX-
6TX+
7GPi (defined by Apple)
8RX+

The O2's male DB9 serial ports have the same IBM PC 232 pinout as Octane, Onyx2, and Origin. The O2's ports do not do 422 or Macintosh levels; you need a converter (source: man serial(7) on IRIX 6.4).

Support This SiteMore than 1000 hours of work have gone into making this site. Please support my work and ongoing site improvements in one of these ways:
donate now   Donate Now
Use your credit card or PayPal to donate in support of the site.
get anything from amazon.com
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get my thai dictionary app
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get my thai phrasebook app
Experience Thailand richly with my Talking Thai-English-Thai Phrasebook app.
get my chinese phrasebook app
Visit China easily with my Talking Chinese-English-Chinese Phrasebook app.
get thailand fever
I co-authored this bilingual cultural guide to Thai-Western romantic relationships.
CopyrightAll text and images copyright 1999-2017 Chris Pirazzi unless otherwise indicated.
Support This Site

More than 1000 hours of work have gone into making this site. Please support my work and ongoing site improvements in one of these ways:
donate now   Donate Now
Use your credit card or PayPal to donate in support of the site.
get anything from amazon.com
Use this link to Amazon—you pay the same, I get 4%.
get my thai dictionary app
Learn Thai with my Talking Thai-English-Thai Dictionary app: iOS, Android, Windows.
get my thai phrasebook app
Experience Thailand richly with my Talking Thai-English-Thai Phrasebook app.
get my chinese phrasebook app
Visit China easily with my Talking Chinese-English-Chinese Phrasebook app.
get thailand fever
I co-authored this bilingual cultural guide to Thai-Western romantic relationships.
Copyright

All text and images copyright 1999-2017 Chris Pirazzi unless otherwise indicated.