PREPARE FOR AN EPIC

CACHE

AND

FLASH

AND

VIRTUAL

MEMMOREY

By Nathan Smith and Max Gisborne

WHAT ACTUALLY IS “ CACHE AND FLASH MEMORY “Cash

cache memory

Cache memory is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data from larger memory.

Cache

memory is sometimes described in levels of closeness and accessibility to the microprocessor. An L1 cache is on the same chip as the microprocessor. (For example, the PowerPC 601 processor has a 32 kilobyte level-1 cache built into its chip.)L2 is usually a separate static RAM (SRAM) chip. The main RAM is usually a dynamic RAM (DRAM) chip.

In addition to cache memory, one can think of RAM itself as a cache of memory for hard disk storage since all of RAM's contents come from the hard disk initially when you turn your computer on and load the operating system (you are loading it into RAM) and later as you start new applications and access new data. RAM can also contain a special area called a disk cache that contains the data most recently read in from the hard disk.

Contributor(s): Abdo Sharif

This was last updated in June 1997

• Flash

• flash memory (flash RAM)

• Flash memory (sometimes called "flash RAM") is a type of constantly-powered nonvolatile memory that can be erased and reprogrammed in units of memory called blocks. It is a variation of electrically erasable programmable read-only memory (EEPROM) which, unlike flash memory, is erased and rewritten at the byte level, which is slower than flash memory updating.

• Flash memory is often used to hold control code such as the basic input/output system ( BIOS) in a personal computer. When BIOS needs to be changed (rewritten), the flash memory can be written to in block (rather than byte) sizes, making it easy to update. On the other hand, flash memory is not useful as random access memory ( RAM) because RAM needs to be addressable at the byte (not the block) level.

• Flash memory gets its name because the microchip is organized so that a section of memory cells are erased in a single action or "flash." The erasure is caused by Fowler-Nordheim tunneling in which electrons pierce through a thin dielectric material to remove an electronic charge from a floating gate associated with each memory cell. Intel offers a form of flash memory that holds two bits (rather than one) in each memory cell, thus doubling the capacity of memory without a corresponding increase in price.

• Flash memory is used in digital cellular phones, digital cameras, LAN switches, PC Cards for notebook computers, digital set-up boxes, embedded controllers, and other devices.

• Contributor(s): Steve Collins and Julian de Silva

• This was last updated in August 1998

BASICALLY

CASH

Cache memory is basically RAM, but instead of being between the hard drive and the CPU, it is next to the

CPU.

IT IS SOLID STATE AND THEREFORE INSTANTLY ACCESSIBLE AS IT IS CONNECTED DIRECTLY TO

THE CPU IT AVOIDS THE MOTHER BOARD THEREFORE BYPASSING THE BOTTLENECK

SYSTEM MAKING IT MUCH FASTER TO READ.

IT IS USED WHEN THE COMPUTER DECIDES TO RUN A PROGRAM. IT FIRST MOVES THE PROGRAM FROM HARD DRIVE TO STANDARD RAM WHICH IS

CONNECTED TO THE CPU VIA THE MOTHER BOARD.

A COMPUTER WITHOUT CACHE MEMORY WOULD RUN THE PROGRAM FROM RAM GOING THROUGH

THE MOTHER BOARD.

BUT A COMPUTER WITH CACHE WOULD TRANSFER THE PROGRAM TO CACHE MEMORY

THEREFORE MAKING IT QUICKER TO RUN.

ALTHOUGH IT DOES NOT IMPROVE THE SPEED OF OPENING A PROGRAM (IF ANYTHING IT WOULD

SLOW THAT DOWN AS IT HAS TO TRANSFER THE DATA FROM RAM TO CACHE), ONCE IT IS OPEN IT

IS QUICKER.

CRITICS USED TO THINK THAT IT ACTUALLY DID NOTHING TO THE USER EXPERIENCE AS IT ONLY

SPEEDS UP A PROGRAM ONCE IT IS RUNNING AND MOST PEOPLE DON’T USE BIG ENOUGH

PROGRAMS FOR THE RUNNING OF THE PROGRAM TO BE A PROBLEM

ALTHOUGH WITH MODERN GAMES, COMPUTERS ARE HAVING TO RUN INCREASINGLY BIGGER

PROGRAMS SO THESE DAYS IT WOULD BE VERY USEFUL. THERE ARE 2 TYPES OF CACHE

MEMORY:

L1 AND L2.

L1 IS WHEN THE CACHE MEMORY IS INTEGRATED

INTO THE CPU CHIP, WHEREAS

L2 IS NEXT TO THE CHIP, ALTHOUGH STILL

CONNECTED DIRECTLY AND NOT VIA THE MOTHER BOARD.

LIKE RAM, CACHE MEMORY IS TRANSIENT AND WILL DELETE ITSELF ONCE THE COMPUTER IS

TURNED OFF.

FLASH

Flash memory is constantly powered,

non- volatile, read-only memory.

Flash:

flash is used for things like memory sticks and sd cards, it is

solid state

VIRTUAL MEMORY

Virtual memory is a way of managing RAM space.

RAM on most computers does not have enough space to run several programs at once, even programs as small as

a word processor, and a web browser.

SO SOME CLEVER PEOPLE INVENTED A THING CALLED VIRTUAL MEMORY.

THE COMPUTER LOOKS FOR SOME STUFF ON RAM THAT HASN’T BEEN USED FOR A WHILE, AND SAVES IT ONTO THE HARD DISC AND REPLACING

IT WITH JUST AN ADDRESS.

WHEN THE CPU LOOKS FOR THAT BIT OF INFORMATION, RAM IS ABLE TO RECOVER IT QUICKLY AS IT HAS THE DIRECT ADDRESS.

THIS GIVES THE FEEL OF AN INFINITE AMOUNT OF RAM FOR SOMETHING AS SMALL AS A 36 GIG RAM.

THE COST

CACHE-PRO

CACHE-DECENT

CACHE-CHEEP

YOU CAN GET 50P MEMORY STICKS TO £1000 SSD’S

Flash memory

HA

HA

HA

MINECRAFT