A register is an easily accessed place on a personal computer for the storing of information. Most computers will contain a register that contains data for the CPU such as keyboard keys and mouse buttons. Some registers may also have special hardware components, and are read-only while others may only be write-held and can be edited by the user. A register can hold many different types of information including the current date and time, the desktop icons, and even stored entries from a spreadsheet or word processor.
The term “processor register” is often used interchangeably with “registers.” Although there is some degree of overlap in the use of these terms, a register is not really part of the microprocessor chip. Rather, it is the location on the computer where the various instructions to run the computer are stored.
Instructions for running a specific application are stored in the instruction register. Instructions to load or save data from the application are stored in the data register. In cases of multitasking, where more than one application is running at the same time on the computer at the same time, the user is able to manipulate the programs simultaneously by using the appropriate registers. For example, a 32-bit register may hold two different programs that are being run at the same time, while a microprocessor register may only hold one program counter for the execution of one program.
Instructions are executed in the instruction register by using a series of instructions which instruct the microprocessor on what instruction to execute. Instructions are then executed by the PC using the data register. Instruction and data registers are independent of each other; however, the instruction register is commonly stored with the data register so that the data register will tell the PC what instruction to execute at any given time. In addition, the two registers do not share any sort of memory location. Instruction and data registers are used to tell the PC what instructions to execute and how to find them.
A register is defined as a memory location that contains a specific binary value. Instructions that specify how to compile a program or function and control the execution of that program are stored in the pc register. An instruction pointer, which is another form of instruction register, is used to locate this particular register. Instructions can also be executed using the ecx register. A dead register, which indicates that execution has ended, is also stored in the pc register.
The pc and ecx are part of the main register system, which is accessed by every microprocessor instruction. Every instruction, such as a push instruction, read from an instruction register, or a pop instruction is performed on the internal registers. Executing these instructions on the correct internal register results in an immediate result. The two extra internal registers, ie. the pc and ecx, are used by the compiler to compile the source code.