If you have ever worked with UV erasable EPROM's, you know the drill of putting a blank device into a programmer, prying chips in and out of sockets, using a UV light to erase devices for reuse and all of that. Flash memory makes this a little better, at least they can be quicky (and electrically) erased and reprogrammed, but there is still the prying in and out of the socket.

A ROM emulator is the answer to all of this, and is better than sliced bread. This is a box with a serial port (or some kind of cable) on one side to connect it to your development machine, and a cable with a connector that plugs into the rom socket of your target system. Once this is all hooked up, you can just sit at your development machine and run version after version of code. The most you might have to do is to hit the reset button on the target to start a new download running. I usually put the commands to download the code right in my makefile.

I have a couple of units called "promice" or "romulator" made years ago by a company called "grammar engine". They no longer seem to be around. The essence of a unit of this sort is a microcontroller of some kind to handle the communication with the host system, and some static ram that serves as the emulated ROM. Some buffers and transceivers to allow the ram to be loaded and then "handed" to the target system and you have the whole thing.

• Reverse engineering a ROM emulator