[openbeos] Re: parallel driver

There are a couple of these in progress (parallel ports). 
I would have to see what Thomas is doing (I haven't looked) to see
how well the drives (Zip, etc) could/would work with this. 

OTOH, parallel is, very much, a dying technology. We should do it, I think,
but I wouldn't put a whole ton of thought into it, since it is the past and not 
the future. 

>
>Since I got a printer, I noticed some cracks in audio streams while printing...
>So I said to myself "just rewrite the parallel driver !"
>
>
>Looking to the /dev/parallel/* interface in  it doesn't seem so complicated...
>The thing is this is only a parallel driver for use by printers (and dongles 
>also, see DGL_*). Since I would like to have a full featured driver, I looked 
>around a bit, and in fact it's not so easy at all... with all those different 
>standards (SPP, EPP, ECP...). A look at the FreeBSD driver makes me think the 
>// port has become an overdevelopped thingy :)))
>
>http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/isa/ppc.c?rev=1.37&content-type=text/x-cvsweb-markup
>
>The EPP compliant devices can be daisy chained on the // port, making it look 
>like a "bus", with the printer eventually being the last item on the bus.
>
>The right(tm) design would be IMHO to have a parport module, that both the 
>parallel (/dev/parallel/*) driver and the SCSI transport modules could use :
>
>parport bus manager module xxx
> +-> parallel driver       xxx
> +-> parscsi bus module    xxx
>       +->  scsi bus manager
>              +-> hdd scsi driver (zip...)
>              +-> scanner driver...
>
>where xxx are the parts do do.
>
>I still didn't check how BeOS handles DMA exactly... seems there is something 
>called CAM (like in FreeBSD) that deals with it...
>
>So for now what I wonder is :
>- should I code directly all this for NewOS, or first on BeOS since we want to 
>have quite the same interface ?
>- should I implement the full thing or just a parallel driver like the BeOS 
>one ? (which means things would need to be reworked later...)
>
>François.
>
>

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