Computer Memory

Computer memory is any physical device capable of storing information temporarily or permanently.
Memory is the most essential part of a computer.
Without memory there would be no computer, as we know it today.
Modern computers use semiconductor memory
It is made up of thousands of circuits (paths) for electrical currents on a single silicon chip
This can be divided into three categories
-Internal processor Memory
-Main Memory
-Secondary Memory

1. Computer Memory Shaikh Ashraful Alam Department of ACCE BSMRSTU Email:[email protected]

2. COMPUTER MEMORY Computer memory is any physical device capable of storing information temporarily or permanently . Memory is the most essential part of a computer. Without memory there would be no computer, as we know it today. Modern computers use semiconductor memory It is made up of thousands of circuits (paths) for electrical currents on a single silicon chip This can be divided into three categories -Internal processor Memory -Main Memory - S econdary Memory Shaikh Ashraful Alam |ACCE,BSMRSTU

3. Types of MEMORY I. PRIMARY MEMORY OR MAIN MEMORY Random Access Memory ( RAM) Read Only Memory (ROM) II.CACHE MEMORY Level 1 (L1) cache Level 2 (L2) cache III. SECONDARY MEMORY Optical Media Devices Magnetic Media Devices Shaikh Ashraful Alam |ACCE,BSMRSTU

4. I. Primary Memory (Main Memory) Primary memory holds only those data and instructions on which the computer is currently working. It has a limited capacity and data is lost when power is switched off. It is generally made up of semiconductor device. It is the working memory of the computer . Faster than secondary memories . It is divided into two subcategories RAM and ROM. Primary Memory Shaikh Ashraful Alam |ACCE,BSMRSTU

5. I. Primary Memory : Random Access Memory (RAM) This is a type of memory serves as Main Memory Of A Computer. It temporarily stores copy of information and files loaded from a computer hard drive  that are required by a processor. It is volatile in nature, which means that data will be erased once supply to the storage device is turned off. RAM stores data randomly and the processor accesses these data randomly from the RAM storage. RAM Shaikh Ashraful Alam |ACCE,BSMRSTU

6. I . Primary Memory : Types of Random Access Memory (RAM) The RAM chips are of two types. Dynamic RAM(DRAM) A type of RAM that stores each bit of data in a separate  capacitor within an integrated circuit. Static RAM (SRAM ) It is a type of memory in which, memory refreshing is not required. Shaikh Ashraful Alam |ACCE,BSMRSTU

7. I . Primary Memory: Read Only Memory(ROM) It performs only read function not write function. So the data stored in ROM cannot be modified. It comes with special internal electronic fuses that can be programmed for a specific configuration. Once this pattern is established it stays in the unit. Thus, ROM is nonvolatile Shaikh Ashraful Alam |ACCE,BSMRSTU

8. I . Primary Memory: Types of Read Only Memory(ROM) Programmable read-only memory (PROM ) Electrically Erasable Programmable Read-Only Memory (EEPROM ) Erasable programmable read only memory (EPROM) Shaikh Ashraful Alam |ACCE,BSMRSTU

9. I . Primary Memory:Capacity In computer’s memory both programs and data are stored in the binary form The binary system has only two values (bits ) 0 and 1. Each of RAM’s locations stores one byte ) 8 bits) (1 kilobyte is 1024 bytes) (1Megabyte is 1024 kilobytes) (1 terabyte is 1024 megabytes) Thus 64 kilobyte (KB) memory is capable of storing 64 X 1024 = 32,767 bytes Shaikh Ashraful Alam |ACCE,BSMRSTU

10. II . Cache Memory Cache memory is a very high speed semiconductor memory which can speed up the CPU. It acts as a buffer between the CPU and the main memory . It is a high speed storage mechanism. It can be either a reserved section of main memory or an independent storage device. Cache Memory Shaikh Ashraful Alam |ACCE,BSMRSTU

11. II . Cache Memory: Advantage and Disadvantage Advantages The advantages of cache memory are as follows − Cache memory is faster than main memory. It consumes less access time as compared to main memory. It stores the program that can be executed within a short period of time. It stores data for temporary use. Disadvantages The disadvantages of cache memory are as follows − Cache memory has limited capacity. It is very expensive Shaikh Ashraful Alam |ACCE,BSMRSTU

12. II. Cache Memory: types Level 1 (L1) cache Built inside the CPU. Level 2 (L2) cache Built external to CPU, in the motherboard. Shaikh Ashraful Alam |ACCE,BSMRSTU

13. III. Secondary Memory These are magnetic and optical memories. It is known as the backup memory. It is a non-volatile memory. Data is permanently stored even if power is switched off. It is used for storage of data in a computer. Computer may run without the secondary memory. Slower than primary memories Secondary Memory Shaikh Ashraful Alam |ACCE,BSMRSTU

14. III. Secondary Memory:types It is broadly of two types- MAGNETIC MEDIA It is a form of non-volatile memory. The information is accessed using one or more read/write heads. HARD DISKS and FLOPPY DISKS are such devices Hard disks have storage capacity between 80 to 300 GB. OPTIC MEDIA Optic devices are generally circular disc which can contain data encoded in bumps on a special material on one of its flat surfaces . These are broadly of two types-a) CDs and b) DVDs Hard disk Floppy disk CD DVD Shaikh Ashraful Alam |ACCE,BSMRSTU

15. Conclusion Memory plays great role in computer systems. As we have discussed, there are three computer memory types available in standard computer based on their function and physical makeup. However, only the main memory that can be upgraded and changed, the others comes with the system whether it is a processor, ROM or graphics card. Shaikh Ashraful Alam |ACCE,BSMRSTU

16. Shaikh Ashraful Alam |ACCE,BSMRSTU