This memory is like our brain which is able to store and remember previous tasks. Similarly, term memory in a computer represents a chip that stores data. This enables us to retrieve the stored data. It retrieves data and instructions stored in memory for processing the data. Memory storage capacity depends on the type of memory package. Data and instructions entered into the computer system by input units are stored in the computer by some storage media. This storage media is known as memory.
Memory is an important function of a computer where all data and information are stored as binary digits (0 and 1). Memory is a computer system that is required for post-retrieval processing of data and instructions. The computer system uses various devices to store instructions and data. What is needed for its operation is usually that we classify a computer into two basic categories.
Data and instruction memory have two main functions: to store the results of computation to store programs, data and information in the computer. Requires memory. Now you know what computer memory is, now you know about the units of computer memory.
Computer Memory Units
1 Bit = 1 bit
Nibble = 4 bits
Byte = 8 bits
1 KB = 1024 Bytes
1 MB = 1024 KB (Kilobytes)
1 GB = 1024 MB (Megabytes)
1 TB = 1024 GB (Gigabytes)
1 PB = 1024 TB (Terabytes)
1 EB = 1024 PB (Petabytes)
1 ZB = 1024 EB (Exabytes)
1 YB = 1024 ZB (Yottabytes)
Types of Memory
Memory has two types of Volatile Memory and Non-Volatile Memory. Volatile Memory temporarily stores data as soon as the system’s Power Supply is shut down, it loses data. Non-Volatile Memory stores the data permanently even if the Power Supply of the system is turned off. Further, memory is primed (Primary), Flash and Cache memory are classified.
What is Primary Memory?
Primary memory is memory by which data, information, and programs are temporarily stored. Primary memory is the total amount of memory installed on the computer. Primary memory is divided into RAM and ROM. What is computer memory and how many types of computer memory.
What is RAM?
RAM (Random Access Memory) is a semiconductor based memory. It is a temporary memory. It can read and write data from CPU or other hardware devices. It temporarily stores the data. When the system is shut down, it loses data. As a result, RAM is used as a Temporary Data Storage Area.
RAM is mainly of two types –
- Static Random Access Memory (SRAM)
- Dynamic Random Access Memory (DRAM)
- Static RAM: – SRAM is a type of semiconductor memory. It stores data as long as power is supplied to the system. Once the power is turned off, the data stored in SRAM is lost. SRAM uses six transistors for each memory cell. Due to the large number of transistors in the cell, memory cells are not refreshed repeatedly so the data is not long-term. To refresh a cell means to re-write data in a cell. SRAM accesses data much faster. The data access speed of SRAM behaves like cache memory, so it is also used by Cache RAM SRAM is expensive as compared to DRAM.
- Dynamic RAM: – Lifetime of data in DRAM is very less. The data is for about four milliseconds. DRAM is stored in memory cells. Each memory cell contains a pair of a Transistor and a Capcitor. Each memory cell is referred to as little data, small amount of information that can work with the system. The memory cells of the DRAM are refreshed by the DRAM controller to retain data in memory after every few milliseconds. In DRAM, memory cells are arranged in rows and columns. Each cell has a Rows and a columns Reference Number. The DRAM cell accesses the data using the Reference Number. DRAM is less expensive than SRAM.
Different types of DRAM that are used in a Desktop Computer:
- SDRAM (Synchronous Dynamic Random Access Memory)
- RD RAM (Rambus Dynamic Random Access Memory)
- DDR1 RAM
- DDR2 RAM
- DDR3 RAM
- DDR4 RAM
- DDR5 RAM
What is ROM ?
ROM is only for reading data, it stores data permanently and is a Non-volatile Memory. This system does not lose data even after shutdown. Consequently, ROM is a permanent data storage area. There are different types of ROMs: –
- PROM (Programmable Read Only Memory)
- EPROM (Erasable Programmable Read Only Memory)
- EEPROM (Electrically Erasable Programmable Read Only Memory)
- PROM: PROM chip is a Programmable Read Only Memory, it stores data permanently and is a Non-volatile Memory. PROM is a memory chip that allows data to be programmed only once. Because of this, PROM chips are often referred to as One Time Programmable (OTP) chips. Permanently erasing the data stored in the PROM The programming of the ROM is sometimes referred to as Burning and requires a special machine called ROM Burner.
- EPROM: Erasable Programmable Read Only Memory means Ultra Violet (UV) rays are used to permanently erase data stored in EPROM. This is easily done with the help of an EPROM Eraser device, which contains a UV light source that erases the data due to a chemical reaction to the chip.
- EEPROM / FLASH ROM: Electrically Erasable Programmable Read Only Memory means data is stored permanently in EEPROM also it is readable only to data and programs. With the help of Electrical Signal, permanently store data is removed. It is also called hybrid memory because it reads and writes similar to RAM, but retains the same data as ROM. It is a mixture of RAM and ROM.
What is Secondary Memory
Secondary memory is used to permanently store data or programs. After powering the computer off, the data or programs stored in memory are not destroyed. Hard Disk, Floppy Disk, Magnetic Tape, CD (Compact Disk), DVD (Digital Video Disk), Memory card (SD Card), Zip Drive, Flash Drive (Pen Drive) , Blue Ray Disk (BD-R Disc) and External Hard Disk Drive are all examples of secondary memory and Permanent Storage Solution is Non Volatile Memory and stores data permanently and all these are examples of secondary memory.