Updated April 20, 2023
Introduction to Register in Microprocessor
The temporary storage locations inside the computer CPU to store data and addresses is called a register. The register file contains all the registers of the microprocessor. In some CPUs, there are some special registers to do specific tasks assigned to them in the system. When the system is designed, special care is given to the architectural details so that registers are taken care for in the system. Many registers are in the system to perform the operations without any interruption and to save time in the operations. Also, a decoder is included in the register to encrypt the data and the files saved.
Explanation
- Any kind of data, an instruction, or an address is stored in the register that is accessed by the system user. Smaller registers are called half registers and the data stored in those registers will be very less. The registration number and designs depend on the processor needs. Index registers are made for modification and whenever there are modifications in the register, these registers are used to change the data.
- A register is located in the computer CPU so that it is easily accessible to the programmers. They can easily work on the registers and modify them based on the need of the system. The storage is limited but it is guaranteed to be fast as it is a temporary storage of data processed in the system. Some registers function only for hardware and may be either read only or write only in the system.
- Data is loaded from the main memory and the instructions for arithmetic operations are carried out in the register. Data is stored in the register for a specific time and delivered to the main memory when asked for. This helps to create temporary storage and permanent storage in the system and thus proper working of the system is maintained in the processor.
- These registers are always kept in the top of the memory system in the computer so that data can be accessed faster in the system. These registers are normally the instruction registers of the processor and works according to the instructions given from the system. In some cases, the CPU has a duplicate of these registers and they are renamed in the system. Performance is improved with the help of these registers. This makes the registers to work in parallel along with the duplicate registers.
- The system may ask for the same data repeatedly and this data might be stored in the registers. These registers are called locality of reference and these registers help the system to perform well due to the speed in which the data is fetched from the register. Either the programmer assigns the data and working to the register or while coding, the compiler assigns data to the register.
- The bits of data that the register can hold vary from one to another. It can be an 8-bit or 32-bit or 64-bit register. It works in different modes so that bigger tasks are broken down into smaller ones and different kinds of data can be loaded and made to work in the system. Data can be of any type and the memory can also vary. When the processors execute one instruction on different kinds of data, it is called a vector processor.
- In many processors, a pseudo register is added to the system that always returns zero when the data is fetched. It helps to simplify indexing nodes in the system and cannot overwrite when data is needed. So mostly one cannot determine how many registers are usable in a processor. When there are 16 registers, we can say that only 15 are usable in the processor.
- Registers receive binary data as input, checks the data available with them and process the input and deliver the output to the system as binary output. Now, a copy of the output is stored in the register. This helps the system to fetch the data for faster processing.
- Registers are classified based on their functionality and behavior. It can be read only or write only, write once and reset to clear data, write many, read to clear, write to clear, and protected in the system. Based on these functionalities, the registers are selected in the system to work for specific purposes in the processor.
Components of Register in Microprocessor
- User accessible registers that is written by the machine instructions and are divided into data and address registers. Data registers hold numbers, characters, and arrays in the system. Address registers save the addresses and can access the primary memory of the system.
- General-purpose registers act as both data and address registers. In some cases, they store floating numbers as well.
- Status registers store the logical values of whether the instruction to be executed or not in the system.
- Floating numbers are stored in Floating-point registers and zero, one or pi are stored in constant registers.
- Vector instructions are stored in vector registers and special purpose registers have the program state of the system. It includes a program counter and status register.
- Model-specific registers or machine-specific registers has the data and settings of the processor in the system. They are specific and cannot be made as standard for the processor.
- Instruction registers has the instructions to be executed at a time and also some registers fetch information from the RAM to store data in the system. They are called memory buffer register and memory address register.
- The architectural register is visible to the software of the architecture and works only corresponding to the software.
- Also, there are hardware registers but they are working outside the CPU and performs the hardware related operations of the system.
The efficiency of the system could be increased by adding the number of registers so that different purposes are carried out in the system. Compilers improve efficiency by improving code optimization. Special purpose registers can be coded to do some special tasks in the system.
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