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SubjectRe: Parallel, IEEE 1284, Zip drive
Date
Ulrich Windl says:
> On 9 Apr 96 at 22:07, Grant R. Guenther wrote:
> > Albert Cahalan wrote:
> > >
> > > We have a problem.
> > >
> > > PLIP, Zip drives, printers, status bars, ...
> > > 8/4 bit, 8/8 bit, sometimes 8/8 bit, IEEE this and that...
> > >
> > > It seems that the port driver should be apart from the device.
>
> Good idea! I'm thinking of repeated implementations of EPP modes,
> etc.

Fine, as far as that goes ...

> > It is certainly worth thinking about, but I don't know if it will gain us
> > very much. If all the devices were 1284 compliant, then it would be
> > possible to design a 1284 API and implement drivers for the different
> > kinds of physical ports, but PLIP isn't a 1284 device, and from my
> > work implementing the driver for the ZIP I don't think it is either.
>
> I think "port driver" was not meant to be "parallel SCSI
> interface"...

I don't believe I made any such suggestion - certainly not in the paragraph
you are responding to. IEEE 1284 is a signalling standard for devices
on a "parallel" bus. It implies an API (just *like* SCSI is a signalling
standard that also implies a particular programming model). To that
extent, it would be meaningful to devise such an API and implement low-level
drivers for the different parallel ports out there ...

But, Albert seemed to suggest that the ZIP drive, PLIP, and the status
bars could be encompassed by this new API / driver structure.

Without some sort of common API or common hardware spec it is meaningless to
talk about writing a device driver. PLIP, PPA and 1284 all use
the bus in entirely different ways, so there is little hope for a common API
that includes the specific devices that Albert mentions.

But, it would still be a good idea to implement 1284 drivers for the
different ports - just don't expect non-1284 "devices" to be able to use
them.

By the way, since you mention "repeated implementation of EPP modes", do
we actually have *any* implementations around ? I'd certainly like to
see what people have done ...

--------------------------------------------------------------------------
Grant R. Guenther grant@torque.net
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