[comp.os.os9] Device driver for fast character peripheral

davidb@inmos.co.uk (David Boreham) (11/28/90)

From: davidb@inmos.co.uk (David Boreham)
Path: inmos.co.uk!davidb
Newsgroups: comp.sys.os9
Subject: Device driver for fast character device.
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I'm working on interfacing a peripheral which does 1Mbyte/s
to an OS/9-68000 system. If you use an SCF device driver,
you can not sustain anything like that data rate because
you have to go through the operating system for each 
character.

In UN*X, character devices are allowed to pass read/write
calls for multiple bytes directly to the device driver and
so achieve high performance. This is not possible with standard
SCF device drivers and the standard file manager.

I would really appreciate help from anyone out there who has
any ideas or who has implemented a similar interface.

Is there another file manager available which would be better ?

Thanks in advance, David.

David Boreham, INMOS Limited | mail(uk): davidb@inmos.co.uk or ukc!inmos!davidb
Bristol,  England            |     (us): uunet!inmos.com!davidb
+44 454 616616 ex 547        | Internet: davidb@inmos.com

meindert@inducom.UUCP (Meindert Kuipers) (11/29/90)

From article <12774@ganymede.inmos.co.uk>, by davidb@inmos.co.uk (David Boreham):
> 
> I'm working on interfacing a peripheral which does 1Mbyte/s
> to an OS/9-68000 system. If you use an SCF device driver,
> you can not sustain anything like that data rate because
> you have to go through the operating system for each 
> character.
.
.
> Is there another file manager available which would be better ?
> 

Yes, we have done a little thing like that. It is basically an
empty file manager, which passes read and write requests directly
to the driver. It is not a product however, because it has to be
modified depending the specs of the hardware and user software.
It is not always useful to do a filemanager, other solutions are
available like getstat/setstat in an SCF-driver or a traphandler
(possibly in system state).
Give us a ring to check out the possibilities.

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