We had this idea. a 8051 programmer for all devices. we choose pins and voltages (and current?) with a multiturn switch. tell us What do you want programmed. do you want to join us? Ralesh will start the sourceforce sproject. go Ralesh :)
Like the other respondants, I feel that you are wasting your time on a do nothing project. Having said that, let me make a few observations. First, to be truly universal you will need a pin driver for each and every pin for the maximum number of pins that you want to program. Each pin driver will need to drive (source or sink) at least 2.7 Volts, 3.3 Volts, 5 Volts, 12 Volts and 15 Volts. Some devices may allow pins in parallel but you don't know which pins until you have studied each and every data sheet. Then you will need to study the programming sequence for each and every device that you plan to support. Also, today's 8051 family devices have programming adapters and boot code built-in. Just look at one family, the Silabs parts. A two pin adapter and free software and you can program and debug almost the entire Silabs family of 8051 parts. Personally, it might be a fun project to knock around but it would be more fun and have more advantages if you would spend half the time to build a USB Logic Analyzer or a USB Network Analyzer. To echo the other responders, don't attempt a project that has few, if any rewards. Bradford