Early mechanical registers were entirely mechanical, without receipts. The employee was required to ring up every transaction on the register, and when the total key was pushed, the drawer opened and a bell would ring, alerting the manager to a sale taking place. Those original machines were nothing but simple adding machines.
In 1906, while working at the National Cash Register company, inventor Charles F. Kettering designed a cash register with an electric motor.
Cash registers include a key labeled "No Sale", abbreviated "NS" on many modern electronic cash registers. Its function is to open the drawer, printing a receipt stating "No Sale" and recording in the register log that the register was opened. Some cash registers require a numeric password or physical key to be used when attempting to open the till.
A cash drawer is usually a compartment underneath a cash register in which the cash from transactions is kept. The drawer typically contains a removable till. The till is usually a plastic or wooden tray divided into compartments used to store each denomination of bank notes and coins separately in order to make counting easier. The removable till allows money to be removed from the sales floor to a more secure location for counting and creating bank deposits. Some modern cash drawers are individual units separate from the rest of the cash register.
A cash drawer is usually of strong construction and may be integral with the register or a separate piece that the register sits atop. It slides in and out of its lockable box and is secured by a spring-loaded catch. When a transaction that involves cash is completed, the register sends an electrical impulse to a solenoid to release the catch and open the drawer. Cash drawers that are integral to a stand-alone register often have a manual release catch underneath to open the drawer in the event of a power failure. More advanced cash drawers have eliminated the manual release in favor of a cylinder lock, requiring a key to manually open the drawer. The cylinder lock usually has several positions: locked, unlocked, online (will open if an impulse is given), and release. The release position is an intermittent position with a spring to push the cylinder back to the unlocked position. In the "locked" position, the drawer will remain latched even when an electric impulse is sent to the solenoid.
An often used non-sale function is the aforementioned "no sale". In case of needing to correct change given to the customer, or to make change from a neighboring register, this function will open the cash drawer of the register. Where non-management staff are given access, management can scrutinize the count of "no sales" in the log to look for suspicious patterns. Generally requiring a management key, besides programming prices into the register, are the report functions. An "X" report will read the current sales figures from memory and produce a paper printout. A "Z" report will act like an "X" report, except that counters will be reset to zero.
Registers will typically feature a numerical pad, QWERTY or custom keyboard, touch screen interface, or a combination of these input methods for the cashier to enter products and fees by hand and access information necessary to complete the sale. For older registers as well as at restaurants and other establishments that do not sell barcoded items, the manual input may be the only method of interacting with the register. While customization was previously limited to larger chains that could afford to have physical keyboards custom-built for their needs, the customization of register inputs is now more widespread with the use of touch screens that can display a variety of point of sale software.
Modern cash registers may be connected to a handheld or stationary barcode reader so that a customer's purchases can be more rapidly scanned than would be possible by keying numbers into the register by hand. The use of scanners should also help prevent errors that result from manually entering the product's barcode or pricing. At grocers, the register's scanner may be combined with a scale for measuring product that is sold by weight.
In stores that use electronic article surveillance, a pad or other surface will be attached to the register that deactivates security devices embedded in or attached to the items being purchased. This will prevent a customer's purchase from setting off security alarms at the store's exit.