memory classification
- 1. K.C.S.KASI NADAR COLLEGE OF ARTS & SCIENCE (Belongs to S.V.H.N.A. Dharma fund) Accredited with B++ Grade by NAAC DEPARTMENT OF COMPUTER SCIENCE MEMORY By Mrs.B.RAMA PRABHA, ASSISTANT PROFESSOR, DEPARTMENT OF COMPUTER SCIENCE 1
- 2. Topics to be Covered Memory Classification of Memory RAM ROM Secondary Memory 2
- 3. Memory It refers to the physical devices used to store programs (sequences of instructions) or data (e.g. program state information) on a temporary or permanent basis for use in a computer or other digital electronic devices. It is required for storage and subsequent retrieval of the instructions and data. It exhibits a wide range of technology and types. 3
- 5. RAM RAM stands for Random Access Memory. RAM loses its contents when the power is turned OFF. RAM is also called volatile memory. The microprocessor can write into or read from this memory. The read/ write memory (R/W M) is popularly known as Random Access memory (RAM). 5
- 6. DRAM(Dynamic Random Access Memory) Dynamic RAM also known as DRAM, its stored information in a very short time (a few milliseconds) even though the power supply is ON. The Dynamic RAM are cheaper and moderate speed and also they consume less power. 6
- 7. SRAM(Static Random Access Memory) Static RAM- Static RAM also known as SRAM ,retain stored information as long as the power supply is ON. SRAM are of higher coast and consume more power . They have higher speed than Dynamic RAM RAM SRAM DRAM 7
- 8. ROM(Read Only Memory) ROM does not loses its content when the power turned off. It’s a NON VOLATILE Memory. The Microprocessor can only read from this memory. Types of ROM: Masked ROM PROM EPROM EEPROM FLASH 8
- 9. Masked ROM In this ROM, a bit pattern is permanently recorded by the masking and metallization process. 9
- 10. PROM(Programmable Read Only Memory) PROM stands for Programmable Read Only Memory. This memory has nichrome or poly-silicon wires arranged in a matrix; these wires can be functionally viewed as diodes or fuses. This memory can be programmed by the user with a special PROM programmer that selectively bums the fuses according to the bit pattern to be stored. The process is known as “burning the PROM,” and the information stored is permanent 10
- 11. EPROM(Erasable Programmable Read Only Memory) This memory stores a bit by charging the floating gate of an field effect transistor. Information is stored by using an EPROM programmer, which applies high voltages to charge the gate. All the information can be erased by exposing the chip to ultraviolet light through its quartz window, and the chip can be reprogrammed. Because the chip can be reused many times, this memory is ideally suited for product development, experimental projects, and college laboratories. 11
- 12. EEPROM(Electrically Erasable Programmable Read Only Memory) • This memory is functionally similar to EPROM, except that information can be changed by using electrical signals at the register level rather than erasing all the information. • If EE-PROMs are used in the systems, they can be updated from a central computer by using a remote link via telephone lines. • This memory also includes a Chip Erase mode, whereby the entire chip can be erased in 10 ms. • This memory is expensive compared to EPROM or flash memory. 12
- 13. Flash Memory This is a variation of EE-PROM that is becoming popular. The major difference between the flash memory and EE-PROM is in the erase procedure. The EE-PROM can be erased at a register level, but the flash memory must be erased either entire level or at the sector (block) level. These memory chips can be erased and programmed at least a million times. 13
- 14. SECONDARY MEMORY Secondary Memory / Non Volatile Memory– Secondary Memory is external memory of the computer. It is also known as Auxiliary memory and permanent memory. It is used to store the different programs and the information permanently. Secondary Memory is nature non volatile. It means data is stored permanently even if power is switched off. The secondary storage devices are: – Floppy Disks – Magnetic (Hard) Disk – Magnetic Tapes – Pen Drive – Winchester Disk – Optical Disk(CD,DVD) 14
- 15. Thank You!! 15