Hello David,

As it happens, I understand exactly what you want to do. It's precisely the approach I took. The minimal number of ICs you need are 1) a MAX3223 (or maybe it's MAX2332, I can never remember without looking it up) to interface to an RS232 serial port. And 2) a microcontroller. I recommend the ATMEL AT89C51RB2 or AT89C51RC2 microcontrollers because they include FLASH memory right there on the chip that can be programmed with the internal bootloader right over the serial port. Other than those two chips, you'll need a crystal (I use 24 MHz) and a few capacitors. The only software you will NEED is Windows Hyperterminal (standard Windows accessory), though ATMEL does provide FLIP as a free download. Even if you eventually start using FLIP for convenience sake, or spring for one of the high dollar IDEs, it is more than worth the effort to get a microcontroller up and programmed with Hyperterminal simply for the learning exercise. No amount of timing diagrams and datasheets can replace the value of watching it happen on your own oscilloscope and/or logic analyzer. If you want to discuss this further, or if you want schematics, email me directly. I will be happy to help you with this.