Mail Archives: djgpp/2001/03/28/04:39:27
On Tue, 27 Mar 2001, BT wrote:
> I am writing an emulator, and now have discovered that it would be the most
> useful thing in the world to emulate the parallel port of that computer via
> the PC's parallel port. Rather than mess about with port numbers and such
> like though, I thought I might just use one of the DOS devices lpt: or prn:.
> I don't know if these are properly implemented in DOS though, and suspect
> like many other things they may be highly dependant on the code that uses
> them doing most of the work, hence my post here rather than somewhere else.
>
> So, my questions - assuming I open with fopen :
First, the system parallel port is already open when your program
starts: either use the stdprn stream, or write to file handle 4.
If you do want to open, use "lpt1" and "prn", not "lpt1:" or "prn:".
If you use the colons, the open will most probably fail, because the
DOS device's name does not include the colon. ANd don't forget to
open in binary mode!
> is there any reinterpretation of bytes sent to these devices? e.g. if I have
> an Epson FX and I send Epson FX escape codes, do my Epson FX escape codes
> get all the way to my Epson FX?
There's no interpretation, whatever you send gets to the printer
verbatim, since the pre-connected stream is in binary mode.
> are (either of) these devices supported in the 'DOS' boxes of NT and 2000?
AFAIK, they are all supported on all versions of Windows, except that
Windows can capture a port and redirect it to a networked printer.
This is determined by the properties of the printer(s) installed on
the particular machine.
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