The Krusty Krab cash register (also called Betsy,Cashy, and Kassie) is a cash register and the co-owner of the Krusty Krab. It first appears in the pilot episode "Help Wanted," and has its first major appearance in "SpongeBob SquarePants vs. The Big One." It appears in most episodes that feature the Krusty Krab.
It is a slate-gray or dark-blue cash register whose sole purpose is to store money given by customers at the Krusty Krab, like any other cash register.
Mr. Krabs got it when it was just a little calculator and raised it as if it was his own child . Like Karen Plankton, it was a calculator when it was younger.
Krabs refers to this technology as an automated money-handling system.
It could be concluded that the register is prohibited to be touched by any non-employee since no one else besides himself, Squidward, or SpongeBob has ever touched it without his worry, as revealed in the "Krusty Krab Training Video."