These are the goals that were used in designing the flash/EEPROM programmer: 1. The more inexpensive the better When you can buy programmers fully built in the $100US to $150US range, a useful circuit should be $50US or less. A programmer and chips that don't require ultraviolet for the erase cycle helps to meet this goal. 2. Easy to build The more wires needed for connections the less likely anyone will want to build it. Heavily using serial interface techniques keep wiring low while minorly affecting performance. 3. Reliable operation Proper powerup & powerdown techniques should be employed to protect the device to be programmed during installation & removal. A high impedance should be present on each pin during these times to guard against false writes and pin input damage. This is the most important goal because it adds predictability to the programming process. Unfortunately due to these goals, this programmer has several disadvantages: 1. Slow Programming a 29F040 (4mbit flash) is reported to take 20 minutes to program on a Pentium 133. 2. Won't program any EPROM chips Because no voltage higher that 5 volts is used in this circuit, the programming of EPROMS is not possible.