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### RS 422

Farago, Peter [remedium2 at vivamail.hu]
Mon, 13 Nov 2006 09:26:43 +0100

Dear James T. Dennis,

I bought a midi interface with rs422 ports,and i read about it(because = this interface quite old)and i know its for macintosh.

But one thing isn't too clear in my mind:

Can i use devices with my pc which are made for macintosh?Because i'm = not sure that those devices are made ONLY for macintosh.

Thanks a lot,

Peter Farago

Hungary

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Benjamin A. Okopnik [ben at linuxgazette.net]
Tue, 14 Nov 2006 09:33:52 -0500

On Mon, Nov 13, 2006 at 09:26:43AM +0100, Faragó Péter wrote:

    >
    >    Dear James T. Dennis,

I'm not Jim Dennis - although he started this whole shebang, he hasn't been around for quite a while - but I'm willing to help to what degree I can.

    >    I bought a midi interface with rs422 ports,and i read about it(because this
    >    interface quite old)and i know its for macintosh.
    >
    >    But one thing isn't too clear in my mind:
    >
    >    Can i use devices with my pc which are made for macintosh?Because i'm not
    >    sure that those devices are made ONLY for macintosh.

In fact, they are. The only internal hardware that I know of that is swappable between Macs and PCs is memory - and even that's not true in all cases. Other than that, Apple's hardware and bus architecture is different from those in the PC, and trying to use pieces of one in the other is, at best, a waste of time (and at worst, the cause of a still-smoking machine being dumped in the trash.)

    --
    * Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET *

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Paul Sephton [paul at inet.co.za]
Tue, 14 Nov 2006 17:47:58 +0200

On Tue, 2006-11-14 at 16:33, Benjamin A. Okopnik wrote:

    > On Mon, Nov 13, 2006 at 09:26:43AM +0100, Faragó Péter wrote:
    > >
    > >    Dear James T. Dennis,
    >
    > I'm not Jim Dennis - although he started this whole shebang, he hasn't
    > been around for quite a while - but I'm willing to help to what degree I
    > can.
    >
    > >    I bought a midi interface with rs422 ports,and i read about it(because this
    > >    interface quite old)and i know its for macintosh.

<snip>

    > In fact, they are. The only internal hardware that I know of that is
    > swappable between Macs and PCs is memory - and even that's not true in
    > all cases. Other than that, Apple's hardware and bus architecture is
    > different from those in the PC, and trying to use pieces of one in the
    > other is, at best, a waste of time (and at worst, the cause of a
    > still-smoking machine being dumped in the trash.)

I am also not Jim Dennis

A very good answer. Never try to plug a card intended for one bus into another. It will probably go up in smoke if it doesn't just break the socket.

What I do know about RS422 interfaces, is that the last time I saw one was on an old PDP 11/23+ around 20 years ago. I have never seen one for the PC at all. The port i/o is in fact quite similar to the RS232, having the same sort of registers and control lines (CD/RTS/CTS/DSR/DTR & signal ground). AFAIK, the only real difference is the distance (I seem to recall 300m) for cable length and supported baud rates.

Linux seems to have a couple of drivers for RS422 under Macintosh sound (this is probably the one), Edgeport, ioc4_serial, Radstone and RocketPort.

Paul Sephton

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