BUT......with the LPT parallel port it is rather nice to be able to mess around with external hardware devices (in REAL TIME no less). If you write your code carefully in the likes of Borland C it can be VERY VERY easy to carry any developed drivers and algorithms over to an embedded platform. For example an 89C51 type platform using Keil C.

I have done this type of development numerous times!!

This can be especially useful if a customer needs something built that they are finding very hard to define exactly what they want. The PC platform lends itself to a test platform with specification development in mind.

For expanding I/Os off the parallel port I have used the Philips I2C to parallel type parts. The required bitbanging on the PC parallel port to talk to I2C is almost identical to the bit-banging done later on a microcontroller port.

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All that said however.......since I discovered Cygnal style development boards with JTAG onchip debugging and hardware breakpoints for about $100 I find the use of Parallel Port prototyping to be a thing of the past. See some articles I have posted regarding developing with the Cygnal parts here....

http://www.8052.com/users/mkaras/CygnalEval.phtml
http://www.8052.com/users/mkaras/Cygnal_ICD.phtml

Michael Karas