[Umberto Zanghieri]'s ZP Engineering srl offers a 
LPTTCL extension [http://www.zpeng.com/projects_tcl_page.htm]
for parallel-port that works 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.

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A few additional notes (''UZ, 29 aug 03''):

    * LPTTCL must be installed and run by a user with administrator privileges (not relevant on Win98)

    * uninstall must be done manually (sorry for this), by deleting the files and by removing the HKEY_LOCAL_MACHINE\SYSTEM\CURRENTCONTROLSET\SERVICES\ZPPORT entry from the Windows registry.

    * LPTTCL only works for low-range I/O (ISA style). If you have a PCI parallel port card that maps into a high I/O, you will not be able to access it from LPTTCL.

    * we received feedback from many programmers that use it for access to custom hardware, development boards and similar. Someone has used it for PLD download, others for I2C bit-bang emulation, others for adding pushbuttons to a PC...

    * LPTTCL does NOT conflict with Windriver-based drivers (i.e., Xilinx parallel port cable), provided, of course, you are not using both on the same port...

    * remember that you need to explicitly specify the LPT base address by issuing a '''lp_setba''' command; there is no detection of base address from BIOS.

[TV] ''(Nov 21 2003)'' I just tried it on XP SP1 on a few year old home pc with tcl 8.4.1, and it works fine with your driver and tcl extension. In fact it seems to process about 300 KiloBytes per second, which is hardly slow, in tcl. Do you consider it reasonable to ask for the sources, for instance of the driver? At least the machine I can use isn't in electronic isolation anymore, which is great! 

For those interested, I'll make a page on [applying the parallel port to drive a LED and read a switch from tcl].

''(15 april 2004)'' Anyone ever try this library with a USB-to-parallel connection ? (I want to know if that could work on a note-book!)

'''UZ''' ''15 apr04'' I never tried, but I think it will not work as LPTTCL works directly on parallel port registers. 

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On Linux (or any other PC Unix) just open the right device (''/dev/parportX'', X = 0 for first port, then 1, 2, etc) and then read and write it as you wish for basic access.
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[Serial port] programming is of related interest.