[comp.sys.ibm.pc] MS/PC-DOS mode command

cjdb@tank.uchicago.edu (Charles Blair) (03/31/89)

I'm trying to figure out how the MODE command works in the case where
one is redirecting LPT1(2,3) output to COM1(2,3,4). DOS Technical
Reference, Norton, (_Programmer's Guide ...) and Duncan (_Advanced
MSDOS_) aren't helping. Basically, I want to emulate this command from
within a program that steals int 5h and does its own print screen
processing. Int 5h and my clone assume a parallel port, but I want to
modify it to allow a user to specify a serial port. All of this
bypasses any MODE command a user might have issued, so I need to
understand what they do, to emulate them.

Specifically, it seems that with parallel to serial redirection in
effect, the operating system somehow bypasses int 5h and does its own
thing. What exactly does it do?

My own solution from within my own code at this point would be to open
AUX as a file, and write to it. Any better ideas? Any tips as to how
MODE does/might work?

Please e-mail responses if possible since there is a lot of stuff in
this group to wade through.

Thanks.
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