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From: papa@pollux.usc.edu (Marco Papa)
Newsgroups: comp.sys.amiga.tech
Subject: Re: DTR and serial.device
Keywords: serial, RS232, modem
Message-ID: <15139@oberon.USC.EDU>
Date: 3 Feb 89 04:16:47 GMT
References: <10511@well.UUCP> <15000@oberon.USC.EDU> <443@madnix.UUCP> <15068@oberon.USC.EDU> <460@madnix.UUCP>
Sender: news@oberon.USC.EDU
Reply-To: papa@pollux.usc.edu (Marco Papa)
Distribution: usa
Organization: Felsina Software, Los Angeles, CA
Lines: 33

In article <460@madnix.UUCP> perry@madnix.UUCP (Perry Kivolowitz) writes:
>That'd be fine by me Marco, but maybe Bryce isn't aware of the existence
>of some weird pieces of equipment  out there which uses DTR as a control
>line which must be diddled while other things are happened on the serial
>port.
>
>One kind of laser disk controller comes to mind....

You're right. DTR handling with close/open is fine for hangup of modems, but 
not for all possible serial devices and uses of it.  A way to control 
individual lines of the serial port (with Perry's way or any equivalent one,
see later) should be included in a new version of the serial device spec.  
This should be made standard ASAP so that all new multiserial devices that 
are now coming to market do it in a compatible way (to make life easier for
us software writers, thank you :-).

One way I like could be to make the opposite of the SDCMD_QUERY command (call
it SDCMD_SET, for example) that can set/clear bits in the same order
as the ones returned in io_Status by SDCMD_QUERY.  This would be easy to
use by a software writer, since all it is needed to set/reset a line would
be:

1. SDCMD_QUERY
2. or/and io_Status with a mask
3. SDCMD_SET

Any thoughts (Perry, Bryce, Aaron) ?

-- Marco Papa 'Doc'
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