OT: DOS programming EPP
- From: Robert Baer <robertbaer@xxxxxxxxxxxxx>
- Date: Sun, 22 Jan 2006 03:14:06 GMT
I have done a websearch, and there is nothing available that eXplicitly shows how to program a parallel port in the EPP mode, and how to *safely* interface with it.
The best (incomplete) source i found was on the beyondlogic.org site.
However, no matter what i do, the nominally input printer pins (pin 1 = strobe, pin 13 = select and pin 15 = error bar) act like outputs.
Data lines when low safely sink 2mA (did not try more as i did not want to zap the MB) R=45 ohms, and when high safely source 1mA (did not try more R=2.2K).
"Strobe" line pin 1 was always high and safely sink 1.5mA R=730 ohms.
"Select" line pin 13 was always high and safely sink 1.0mA R=2.2K.
There seems to be *no* specifications or equivalent circuits for the parallel port as implemented on the ASICs used in modern PCs.
Therefore, it is completely unknown as to the maximum safe sink current to a logic low pin or the maximum source current from a logic high pin.
It is not wise to force a pin that is acting as an output, into the opposite state; so the info is necessary for safety.
I want and need to program this in DOS.
** as an aside, it was interesting to see that when Windoz booted after my fiddling, that i saw "detecting new hardware" etc.
.
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