Register is a noun that can mean an actual book to record things in, or it can refer to any official recording device, such as the one the checkout lady uses to ring up your groceries. It can also be used as a verb, to sign up officially for something, such as registering your car at the DMV or registering for classes at the beginning of the semester. The term can even be used to describe the range of sound you can make with your voice or the emotions you can display: A song sung in a high register is more formal, while one performed in a low register might be more intimate.
In linguistics, the register of a piece of writing or speech is the level and style of language appropriate for the situation or audience: Registers can be informal, such as the huff of exasperation during a debate or a smile when signing “hello.” Register can also be formal, such as the tone of a scholarly text, a letter written to an academic colleague, or the Encyclop
The most common use of register is in point-of-sale systems, where a variety of transactions between customers and businesses are recorded. A cash register is the most familiar example, but it also applies to computerized point-of-sale systems and credit card terminals.
Other types of register include stock and bond certificates, real estate deeds, medical records, and bank account information. Each of these registers contains a collection of authoritative records that are maintained by the government at the county, town, or state level. Each of these registers typically includes the names, addresses, and occupations of all active shareholders or registrants, and details all transactions that have been made.
A register is also a kind of database, containing data organized in a systematic way for ease of retrieval and reporting. A mortgage loan register, for example, is a kind of database that helps banks manage the mortgages they issue and track each borrower’s payment history. The information in these databases is organized into rows and columns, and each entry has a unique number that indicates where the record is located in the register.
In computers, registers are the secret to CPU performance: They help it get data quickly, follow instructions smoothly, and handle everything else happening inside the processor. Different registers have different jobs, but they are all essential to making computers work well.
There are many kinds of registers, but all are designed to hold and transmit data. The most commonly used register is the memory-mapped register, which stores data directly in a memory location. A CPU can read and write to a memory-mapped register by simply accessing that location in the address space, without the need to first fetch an instruction or read or write a memory address.
Another type of register is the multiscalar register file, which is used in segmented memory architectures to store address data for different functions: CS, DS, and SS (for code, data, and stack segments). These registers can save area by avoiding multiple copies of the same block of logic.