[Coco] OS-9 device descriptor list

[gene heskett]

On Saturday, January 08, 2011 09:09:21 pm Willard Goosey did opine:

> On Sat, Jan 08, 2011 at 01:04:25PM -0500, gene heskett wrote:
> >     6 $E1 $A70A4C . Parallel
> >     6 $F1 $01146A . LP
> 
> OK, yet another parallel port driver and descriptor, I assume.  Brief
> description please?
> 
> Willard

Very simple, only chokes if the printer is on fire or out of paper, 8 bit 
parport driver.  In this case for the parport on the SC-II+4n1.

None of these so called parport drivers are 'bulletproof' Willard, and 
after the FCC made printers grow some noise filters, few if any worked 
correctly and likely never will until some enterprising soul actually gives 
us a bit of parport hardware that actually latches the data and handshakes 
with the printer so it knows the printer got it.  The problem is that the 
data is only valid for about half an E-clock, along with the strobe to the 
printer, then its gone, tristated till the next byte gets written.  With 
the noise filters present at the Centronics port of the printer since the 
commish tried to quiet them down, 1/2 an E-clock is simply not enough time 
for the data to become valid on the other side of those filters. It needs 
around a 3 u-second hold time per byte.  I was gonna stick a latch and 
flip-flop on the port, but the printer upchucked for other reasons (broken 
pins in the head) and I went back to a serial port and that old xerox 1650-
ro for a printer.  Now of course the 1650-ro still works, but even the 
'new' (insert laff line here) one time ribbons for it are so old they 
shatter like a dropped wine glass on the first character strike.  So now I 
use a cheap brother laser, with cups on this machine in the pipeline doing 
the rasterizing.  At 22 PPM, by far the fastest printer I've ever had 
available to my coco.

-- 
Cheers, Gene
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