[Umberto Zanghieri]'s ZP Engineering srl offers a 
LPTTCL extension [http://www.zpeng.com/projects_tcl_page.htm]
for parallel-port work on Windows 98, NT, and 2000.


A few notes on LPTTCL by UZ.

    * parallel port access on Win98 is rather easy; on the other hand, doing the same on NT and 2000 requires a driver. LPTTCL attempts to provide the same technique on all three platforms.

    * it allows access not only to the data port, but also to control and status registers; this allows for many options (i.e., emulation of EPP cycle access)

    * it is not speed optimized; bit-by-bit control is rather slow.

    * it has been designed for simple control of external devices and emulation of serial protocols as I2C.

Users have reported that it works correctly under Windows XP.


[[Many other references.]]

[[Basic applicable technique is to open the port (by name) and write to it.]]

=)



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On Linux (or any other PC Unix) just open the right device (''/dev/???'') and then read and write it as you wish for basic access.
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[Serial port] programming is of related interest.