Subject: Re: Help! I cannot print to lpt port.
To: Terry Moore <tmm@mcci.com>
From: Ken Hornstein <kenh@cmf.nrl.navy.mil>
List: port-i386
Date: 10/06/1995 15:31:13
>> Have you tried simply copying something to /dev/lpt2?  I suspect you
>> don't have an interrupt configured for that port, and therefore you
>> need to use /dev/lpa2.  If you try to open /dev/lpt2 with no interrupt
>> configured, you'll get ENXIO.
>
>This reminds me -- has -current sorted out the "dropped characters from
>printer driver" problem that was discussed and experimented upon back
>in March or so?

As I recall, the gist of it was:

- It wasn't actually "dropped" characters.  The right number of characters
  were being printed, but characters ended up having the value of the
  previous or next character, instead of the proper one.

- Many timing diagrams of proper parallel port operation were posted.  I
  don't recall that any of them worked when implemented :-)

- The polling version of the driver works, and it seems that's what other
  OS's use in "real life" (I believe someone mentioned that with Linux's
  interrupting parallel port driver has a bunch of delays that you can set).

If anyone else remembers differently, please feel free to correct me.

--Ken