Re: DOS programming EPP

Simone Merrett wrote: 
There are lots of sites with info on programming Parallel port.
here is just one.
http://electrosofts.com/parallel/

I also found the "Extended Capabilities Port Protocol and ISA Interface
Standard" on microsoft site.

The formal definition of EPP port is, I believe, an IEEE publication, that
you can buy, however, to get an idea of the electrical aspects of the port,
I suggest simply finding out what the popular driver chips are that are used
in Intel PCs... and hence find the particular specs you're interested in.
(eg max I/O current of these chips).

Im currently using a EPP to emulate a minimal ISA bus for a "WinRadio".

You dont mention what you mean by programming "..in DOS"... windows? old MS
DOS? (IE via DOS driver)  OR direect to port?
Win / DOS drivers are aimed at printers, so sometimes make it harder than
simply writing your own driver.

Good luck
Dave M.

"Robert Baer" <robertbaer@xxxxxxxxxxxxx> wrote in message
news:2MCAf.1567$Dk.1100@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

  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.



I thank you for the references and will check them out.
Like i said, the parallel port is implimented in an ASIC and so there are *no* "driver chips" period.
I am going to use "real" DOS; any version from 1.0 to 7.1 will work for what i need as the program will read and write diretly to the port.
.

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