SCOUG-HELP Mailing List Archives

<< Previous Message << >> Next Message >>

Date:	Wed, 2 Jan 2002 09:56:20 PST7
From:	"Steven Levine" <steve53@earthlink.net >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: SBLive setup

=====================================================
If you are responding to someone asking for help who
may not be a member of this list, be sure to use the
REPLY TO ALL feature of your email program.
=====================================================

In <3C3302AC.2818@peterskye.com>, on 01/02/02
at 04:57 AM, Peter Skye said:

>Thanks, it's been several years and I can't remember. I do remember
>creating the header in assembler (mostly fields, almost no logic other
>than a jump) and having to write 18 small routines in C, then compiling

The header has addresses, but no jump.

>using Watcom. I still think there was some logic in one of those
>routines that determined whether the interrupt had been handled or not,

You can do it in several places. Typically it's done in the Init routine
using the SetIRQ DevHlp. The parameters declare whether you want shared
or exclusive access to the IRQ.

>therefore hadn't issued the interrupt) you could still claim the
>interrupt as your own thereby shutting out any other driver on that

That's called a defect. :-)

>interrupt. I don't recall what happens when two hardware devices set the
>same IRQ line at the same instant.

Nothing that doesn't happen when a single device yanks the line. There's
no problem with this. Ignoring blatent coding errors, the problems that
do occur when issuing the EOI for an edge triggered interrupt. There's a
race condition that without careful coding will cause a new interrupt
request to be missed. The solution is difficult enough that the OS/2
driver model does not support shared, edge-triggerd IRQ's across drivers.
That does not mean a driver cannot attempt to support this for the devices
it controls. For example, SIO does this. Ray says you should even be
able to run the devices concurrently, but he will not guarantee it.

>Which ones don't you like? :))

I liked them all.

Steven

--
----------------------------------------------------------------
"Steven Levine" MR2/ICE 2.30a #10183 Warp4/FP15
www.scoug.com irc.webbnet.org #scoug (Wed 7pm PST)
----------------------------------------------------------------

=====================================================

To unsubscribe from this list, send an email message
to "steward@scoug.com". In the body of the message,
put the command "unsubscribe scoug-help".

For problems, contact the list owner at
"rollin@scoug.com".

=====================================================

Return to [ 02 | January | 2002 ]

SCOUG, Warp Expo West, and Warpfest are trademarks of the Southern California OS/2 User Group. OS/2, Workplace Shell, and IBM are registered trademarks of International Business Machines Corporation. All other trademarks remain the property of their respective owners.