Highrez

Next up --
The routine to get around the parallel port restriction in Windows has been solved!!
Now to get access to the low memory vectors, specifically the tick timer (int 0x1c) vector Windows restriction.
I want to connect an interrupt.
Any ideas?

Sorry, no idea. But t sounds to me like you need to be writing a proper kernel driver, not anything in user space. That's not going to play well with interrupts I suspect!

Also, the IRQ7 interrupt can be generated through the parallel port's ACK status register bit input if it is enabled in the control register.
But without setting the vector to point to my routine, it is a NOP. Nobody uses IRQ7 so messing around with its vector does no harm.
This does work perfectly in MS DOS since the INT21 bios call can give control of the IRQ7 vector.
But, as you say the kernel would be involved.