Can't read from parallel port

[Greg Montgomery]

I'm having trouble with a vxd that reads from the parallel port. I am using
VToolsD and Borland C++. It works fine if I run another program that reads
from the parallel port first. But until I run this other program, I don't
get any interrupts from the parallel port. Any ideas on what sort of
initialization might be necessary?

Thanks
---
Greg Montgomery / gregm at cc.gatech.edu
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PGP key at http://www.cc.gatech.edu/people/home/gregm

[SonOfTesla]

You need to turn on the interrrupt. Don't really know how to do this with
VTOOLS, but the VxD function I use is VPICD_Virtualize_IRQ. Your problem
may also be that you have not turned on the parallel port interrupt by
setting the control port bit which controls this.
Good luck,
Jordan

[Karen Hazzah]

In article , gregm_sp...@cc.gatech.edu says...

>
>I'm having trouble with a vxd that reads from the parallel port. I am using
>VToolsD and Borland C++. It works fine if I run another program that reads
>from the parallel port first. But until I run this other program, I don't
>get any interrupts from the parallel port. Any ideas on what sort of
>initialization might be necessary?

1. Install an interrupt handler via VPICD_Virtualize_IRQ.
2. Enable interrupts on your device (by writing to some kind of control
register, usually).
3. Enable the IRQ at the PIC by calling VPICD_Unmask_IRQ.
4. Do whatever it is you need to do to get your device to interrupt: send
it a buffer's worth of data, etc. etc.