If this a new project you are working on then you should consider switching over to a FLASH based microcontroller with ISP capability. Your development experience will be far more productive and rewarding.

If you are upgrading an existing product with an external program EPROM then truly you should look at substituting the mocrocontroller with a FLASH based one. The FLASH would be on board and you can eliminate the external EEPROM. (I did a project a while back wherein I needed to do some debugging of a program in a EPROM based 87C52 type part and did this little number!

If you have no choice but to be working with the EPROM then you have my sympathy. However....here are some ideas.

There are commercial products that are called EPROM emulators. Here is one such link:
http://vault1.secured-url.com/comsol/ac...ators.html

Here is a link to an article that talks a bit about an EPROM emulator called the PromIce.
http://www.circuitcellar.com/library/t.../index.asp

Also note that some of the EPROM programmers on the market can be used as an EPROM emulator. A cable goes from the programmer device socket to the target EPROM socket. You then download the data from the PC to the programmer in the normal manner. Here is a link to one such programmer that is being sold on eBay: http://cgi.ebay.com/ws/eBayIS...eName=WDVW

Michael Karas