Computer Memory: Main, Secondary, Semiconductor, Magnetic, RAM, ROM, Cache, Study notes of Computer Science

Download Computer Memory: Main, Secondary, Semiconductor, Magnetic, RAM, ROM, Cache and more Study notes Computer Science in PDF only on Docsity! Presented to Md. Rifat Ahmmad Rashid, Lecturer, Department of CIS, Bangladesh University of Business & Technology Presented by 1. name I.D. No. 1011310…. 2. name I.D. No. 1011310…. Computer capacity Bit: Short for binary digit (0s and 1s), the only data that a CPU(Central Processing Unit) can process. Byte: An 8-bit string of data, needed to represent any one alphanumeric character or simple mathematical operation. Types of memory There are three categories of computer memories: Main Memory (Primary Memory) stores small amounts of data and information that will be immediately used by the CPU (Central Processing Unit). Secondary Memory (Auxiliary or Backup) stores much larger amounts of data and information (an entire software program, for example) for extended periods of time. Internal Processor Memory stores temporary storage of instruction and data used as working registers. Main memory Main memory is a large array of data or bytes. It provides storage that can be access directly by the CPU. Major activity of main memory: 1. Keep track of which part of memory currently being used and by whom. 2. Decide which process are loaded into memory when memory space becomes available. 3. Allocate reallocate memory space as needed. Random access memory (RAM): The part of primary storage that holds a software program and small amounts of data when they are brought from secondary storage. Rams are categorised as follows: – SRAM (Static RAM) (flip-flop gates) – DRAM (Dynamic RAM) Types of Main Memory Device Read-only memory (ROM): Type of primary storage where certain critical instructions are safeguarded; the storage is nonvolatile and retains the instructions when the power to the computer is turned off. ROMs are categorised as follows: – PROM (programmable) – EPROM (erasable programmable) – EEPROM (electronically erasable programmable) Types of Main Memory Device Types of Main Memory Device Cache memory: A type of primary storage where the computer can temporarily store blocks of data used more often. Register: registers are part of the CPU with the least capacity, storing extremely limited amounts of instructions and data only immediately before and after processing. • Magnetic Disk Drive • Floppy Disk Drive • Magnetic Tape Drive • Optical Disk Drive Important Secondary Storage Methods Most desktop microcomputer systems have floppy disks, hard disks optical disk drives and High Capacity Floppy Disks. Secondary Storage Devices High Capacity Floppy Disks There are three types of hard disks: – Internal – Hard-disk cartridge – Hard-disk pack Hard Disks Hard-disk cartridge