memory

memory

1. RAM

   • Random Access Memory (RAM) is a hardware device that allows information to be stored and retrieved on a computer. ... However, unlike ROM or the hard drive, RAM is a volatile memory and requires power to keep the data accessible.
     • volatile
       • Volatile memory is computer storage that only maintains its data while the device is powered.
       • Volatile memory contrasts with non-volatile memory, which does not lose content when power is lost. Non-volatile memory has a continuous source of power and does not need to have its memory content periodically refreshed.

2. Cache

   • Cache memory is a small-sized type of volatile computer memory that provides high-speed data access to a processor and stores frequently used computer programs, applications and data. It is the fastest memory in a computer, and is typically integrated onto the motherboard and directly embedded in the processor or main random access memory

3. ROM

   • Short for Read-Only Memory, ROM is a storage medium that is used with computers and other electronic devices. As the name indicates, data stored in ROM may only be read. It is either modified with extreme difficulty or not at all. ROM is mostly used for firmware updates.
     • ROM, PROM, EPROM, EEPROM and Flash memory are types of ROM. Data stored in these chips is nonvolatile -- it is not lost when power is removed. Data stored in these chips is either unchangeable or requires a special operation to change (unlike RAM, which can be changed as easily as it is read).

4. Registers

   • A register is a discrete memory location within the CPU designed to hold temporary data and instructions. When a register is being used to move data /instructions from one part of the system to another, this is called a buffer.
     • buffer
       • In computer science, a data buffer (or just buffer) is a region of a physical memory storage used to temporarily store data while it is being moved from one place to another. ... However, a buffer may be used when moving data between processes within a computer.

5. Flash

   • Flash memory, also known as flash storage, is a type of nonvolatile memory that erases data in units called blocks. A block stored on a flash memory chip must be erased before data can be written or programmed to the microchip. Flash memory retains data for an extended period of time, regardless of whether a flash-equipped device is powered on or off.

6. Solid State

   • Solid State storage is a type of computer storage media made from silicon microchips. Solid State storage stores date electronically instead of magnetically, as spinning hard disk drives or magnetic oxide tape do.

7. Virtual Memory

   • Memory that appears to exist as main storage although most of it is supported by data held in secondary storage, transfer between the two being made automatically as required.
     • For example, virtual memory might contain twice as many addresses as main memory. ... When the page is needed, the operating system copies it from disk to main memory, translating the virtual addresses into real addresses. The process of translating virtual addresses into real addresses is called mapping.

8. disk thrashing

   • In computer science, thrashing occurs when a computer's virtual memory subsystem is in a constant state of paging, rapidly exchanging data in memory for data on disk, to the exclusion of most application-level processing. This causes the performance of the computer to degrade or collapse.

9. firmware

   • permanent software programmed into ROM