The idea behind this EEPROM programmer was to have a tool to get data on a 28Cxxx EEPROM for my own 6502 based computer. There are a lot of professional programmers you can buy, but for a lot of money. Using cheap and easy available components should keep the price low.
The 28Cxx series of EEPROMs are 8 bit, parallel memory chips that are electric (re)programmable and also erasable.
There is a thread on the 6502.org forum covering the development of this programmer.