Reading a Data Stream Going to a Printer

[Sarah]

I would like my vb.net software running on an independent system be able to
read the data going from a proprietary system to a dot-matrix printer. Few
questions - are there any commercially available or "hack" devices available
that would allow me to tap into the data the proprietary system is sending
to the dot matrix printer?

How could I get my vb.net software to respond listen to and respond to this
data stream? Are there any commercially available controls?

Now for those of you asking why would I do this? I have a system that the
DOS based and 100% proprietary that is very important - but, I need to
monitor the data from it when it prints to the dot-matrix printer - so, thus
comes the need for an independent system that can monitor and read the data
stream going to the printer.

Any help/guidelines would be appreciated.

[Fergus Cooney]

Hi Sarah,

If the program is doing its printing via a Dos Printer interrupt, one
possibility is to hook into the interrupt and syphon off a copy of the data.

Regards,
Fergus

[Sarah]

How would you hook into the interrupt from another independent computer
system?
"Fergus Cooney" <fi*****@post.com> wrote in message
news:uK**************@TK2MSFTNGP12.phx.gbl...

Hi Sarah,

If the program is doing its printing via a Dos Printer interrupt, one
possibility is to hook into the interrupt and syphon off a copy of the data.
Regards,
Fergus

[Fergus Cooney]

Hi Sarah,

I wasn't sure exactly what you meant by 'independant' so I focused on the
Dos side of the equation. Being a Dos system means that its interest in the
outside world is zero, so, short of virus-like technology, any interrupt hook
is going to require someone to put it there. It would run as a TSR which would
need to be loaded before the application was started.

I'm sure there are cable-tapping/network-sniffing devices (legitimate) but
that's well beyond my ken.

Regards,
Fergus