How do I reprogram my cash register?

First, you need to have the manual for that cash register. All programming is specific to the brand, and often to the model, of the register - without the manual you are pretty much sunk.
Second, you need a key that will allow you to do programming. On that register, you need the Manager key which has a 'MA' stamped on it. In fact, some programming operations, like clearing the programming of a previous owner or changing configuration options, can only be done by a dealer with a Service key.
Finally, register programming is easy, but easy is a very relative term. It's easy for me because I do it every day. If you've never programmed a cash register, you really should get someone who has (or at least a techie geek-type friend) to help you get started. I don't mean to sound too negative, but getting some experienced help will save a LOT of time and frustration.

Good luck ...

Steve
May 2010