[movitz-devel] Re: off-topic: Poking the parallel port

[Frode Vatvedt Fjeld]

Michael Hansen <mmhansen at gmail.com> writes:

> Specifically, I want to be able to toggle and latch the state of
> four outputs on an x86 parallel port under Movitz. I have been told
> it is going to be more complicated than just fiddling with the
> memory map as might be done with BASIC on a DOS box, since Movitz
> (Muerte?) runs in protected-mode.

I don't think anything is complicated by Movitz running in protected
mode. (Perhaps whomever you talked to were thinking about the
kernel/user-space protection in typical kernels?) You can easily
fiddle with the parallell port under Movitz by saying things like

  (setf (io-port <io-base> :unsigned-byte8) <bits>)

interactively or in a compiled function or whatnot. I don't remember
off-hand the exact details of how one interfaces the PC parallell
port, but I seem to remember that there are about eight pins that can
be controlled in the obvious way by writing to a certain (byte)
I/O-port. The exact details should be easily available on the web or
from one of the books on PC hardware programming.

Don't hesitate to ask more specific questions here if you run into
problems.

-- 
Frode Vatvedt Fjeld