I am a ASIC and FPGA designer and started to use Tk/Tcl as scripting language in ModelSim VHDL simulator.
Has used TCL for debugging and test in product development.
Has implemented a SPI Master by the use of lpttcl.dll refer to Parallel port.
I have experiensed some problems with the lpttcl.dll on some PCs and Windows versions.
Please note that the parallel port some PCs has a 5V output and others(newer) have 3.3 V !