The basic problem with constructions of this class is that WinNT and their descendants such as WinXP, screen the applications from the hardware. SImply put, they don't allow direct writing to ports, and the vast majority of older programs using LPT do exactly this.

You should be able to use FreeDOS, if you can't get some M$DOS (e.g. from a W9x machine).

You might also try to experiment with utilities such as giveio and such, which allow the direct access even under WXP, but there are many gotchas to this, too.

But, even better, forget about LPT-port based gadgets, and get life with some real programmer. You can also get some more life if you forget about AT89[b]C[/b]x051, and go for the AT89[b]S[/b]x051; or even better some of the UART-ISP-able derivatives of '51 such as the 'RD2 subfamily (e.g. AT89C51ED2, P89V51RD2). For hobby, the few extra penny you pay for the chip returns quickly in your spared time.

Jan Waclawek


PS. We at this conference would like to see your whole name in your profile; and, if possible, also your location. Thanks.