Fundamentals of Computer > Computer Memory > Others Memory

Flash Memory

Flash memory is a special type of memory chip that combines the best features of RAM and ROM. Like RAM, flash memory lets a user (or program) access data randomly and it also lets the user overwrite any (or all) of its contents at any time. Like ROM, it is nonvolatile, so it retains data even when power is off. Flash memory is often used in portable digital devices for storage like in digital camera, MP3 player, USB “keychain” storage device, game console etc.

 

Cache Memory

Moving data between RAM and the CPU’s registers is one of the most time-consuming operation a CPU must perform, simply because RAM is much slower than the CPU.

A partial solution to this problem is to include a Cache memory between the CPU and main memory.

Cache memory is used as a high speed buffer between the CPU and main memory for minimizing the memory-processor speed mismatch. When a program is running and the CPU needs to read data or instructions from RAM, the CPU first checks to see whether the data or instruction is in cache memory. If the data that it needs is not there, it reads the data from RAM in to its registers but it also loads a copy of the data into the cache memory. The next time the CPU needs that same data, it finds it in the cache memory and saves the time needed to load the data from RAM. A frequently used program that needs a repeated operation is resided in cache memory.

 

Register

Register is the high-speed memory element that is built directly into the ALU part of the CPU. It holds data and instructions temporarily that are currently being processed by the CPU. The computer loads instruction and data from main memory into the registers just before processing, which helps the computer process faster.

The size of the registers (also called the word size) indicates the amount of data with which the computer can work at any given time.

• The bigger the word size, the more quickly the computer can process a set of data.
• 64-bit processor, or 64-bit register or 64-bit computer means that the word size of the computer is 8 bytes.

Various types of registers used in a personal computer: 

1) Memory Address Register (MAR)     

2) Memory Buffer Register (MBR)

3) Program Control Register (PC)             

4) Accumulator Register (AC),

5) Instruction Register (IR)                        

6) Input/Output Register (I/O)

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Types of ROM

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CPU Memory Interconnection

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