From: mattd@apple.com (Matt Deatherage)
Newsgroups: comp.sys.apple2
Subject: Re: Media Control qs for Matt Deatherage
Date: 2 Sep 92 01:03:28 GMT
Followup-To: comp.sys.apple2
Organization: Developer Technical Support, Apple Computer, Inc.

In article <posty.715315729@ultima>, posty@socs.uts.edu.au (Andrew Roughan)
wrote:
> 
> 
> G'day Matt,
> 
By the way, posting technical questions addressed to only one person is
a good way to keep other knowledgeable people from chiming in.  I
personally
know next-to-nothing about the Media Control tools.

> I'm having an interesting time researching information about writing such a
> driver. Could you possibly enlighten me on the following points?
> 
> MCGetFeatures, mcFeatSel codes:
> mcFVideo:	what exactly is "toggling of video"?
> mcFVDisplay:	what exactly is "video display of the location"?
> mcFVOverlay:	what exactly are "overlay characters"?
> 
> MCControl, ctlCommand codes:
> mcCVideoOn/Off:		what exactly does this accomplish?
> mcCDisplayOn/Off:	what exactly does this accomplish?
> mcCBlankVideo:		what exactly does this accomplish?
> 
I don't know; I've never tried them.  Have you?  I don't even have a
controllable device handy to play with.

> Are there any Apple supplied Macros and Equates files for the Media Control
> Toolset?

If there are, they're on the 6.0 Golden Master CD.  I don't have one handy
and haven't checked.
> 
> There appears to be an inconsistancy between the Media Ctl CDEV and the
> DC Printer CDEV. If Slot 2 is set to "Your Card" in the control panel, the
> DC Printer CDEV still offers "MODEM" as a valid port whereas the Media Ctl
> CDEV does not. This probably holds for Slot 1 as well.

The DC Printer Control Panel records your choices; the Print Manager
complains if the chosen port isn't available at print time.

> Is there a published diagram of the way in which Media Control Device Drivers
> interact with the GS/OS drivers?
> 
Media Control drivers talk to their peripherals however they can.  In some
cases, like the SCSI peripherals, this uses the GS/OS drivers.  In others,
like through the game port, it does not.  It's up to the driver author.

> I have noticed that the Apple IIGS GS/OS Reference and the Apple IIGS GS/OS
> Device Driver Reference make no mention of the MODEM and PRINTER port drivers.
> Is there any additional information available on these?
> 
> The Control L protocol provides a stream of data from the video recorder
> interspersed with gaps. The only way to send a command from the computer is
> to wait for a gap.
> Is it possible for the MODEM and PRINTER port drivers to do this?
> Or will I have to write a Control L port driver? (i.e. like the AppleTalk
> driver)

They are Print Manager port drivers, and documented in Apple IIgs Technical
Note #36.  These are _not_ Media Control drivers and you should not try to
use them as such.

> Andrew Roughan             | Snail: PO Box 65 Wahroonga, NSW 2076 Australia

============================================================================
Matt Deatherage, Developer Support Center, Apple Computer, Inc.
Personal mail only -- please POST technical questions, questions about
Apple and its policies, where to find documents and related inquiries.
The opinions I express don't represent Apple, which makes us both happy.
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