Re: Parallel, IEEE 1284, Zip drive

Albert Cahalan (albert@ccs.neu.edu)
Wed, 10 Apr 1996 22:30:32 -0400 (EDT)

>> 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.
>
> 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.

[Zip and EZ135 are not IEEE 1284]

> There is, however, one thing that *is* desperately needed,
> and that is a sharing protocol. The ZIP drive and the EZ135
> both support chained printers.

What I noticed was that the Zip driver sends bytes directly.
There should be a driver to handle the port hardware.
Quickcam, Zip, PLIP, printers, etc. should use that driver
instead of hitting the hardware directly. They could even
register with the driver.

I think there are some Macs with a normal parallel port.
With Linux for the PowerMac soon, it would be nice to have
just one piece of code to replace.

There are ports sold with advanced features, and it would be
terrible to have to rewrite all the drivers to use the features.
Some multi-mode ports that would take quite a bit of code to
support. I wouldn't want to see the code duplicated for every
parallel port device.