Random Access Memory (RAM)

Functions of RAM in a PC RAM is the workplace where the CPU stores programs that are running. CPU’s short-memory RAM is volatile medium It requires continuous electricity to hold data to store data more or less permanently you need save it to a non-volatile storage (hard disks, floppy) Dynamic Random Access Memory (DRAM) is the primary system memory

Address bus is used to access the chips in RAM sticks CPU uses Static Random Access Memory (L1 and L2 cache) CPU directs the Northbridge chip to update and retrieve data – RAM does not directly connect to the address bus or the data bus. PC has at least one or more small circuit boards, called sticks, usually about 4 inches long Sticks of RAM are divided into small chips which is the actual physical location of the RAM Address bus is used to access the chips in RAM sticks

RAM Technologies Fast page Mode (FPM) RAM original type of RAM used in PCs Obsolete Used in Pentiums and earlier Extended Data Output (EDO) RAM Improvement of FPM RAM Both EDO and FPM are asynchronous Asynchronous RAM speeds are measured in nanoseconds (ns) Used in Pentium II, Pentium, early Celeron and Athlon

Synchronous Dynamic Random Access Memory (SDRAM) has a clock speed (Hertz) PC66, PC100, PC133 66MHz, 100MHz, 133MHz Double Data Rate SDRAM (DDR SDRAM) Advanced, double speed type of SDRAM DDR200 /PC1600, DDR266 / PC2100, DDR333 / PC2700, DDR400 /PC3200 200MHz, 266MHz, 333MHz, 400MHz DDR2 SDRAM PC2-3200 – PC2-8500 200MHz, 266MHz, 333MHz, 400MHz, 533MHz DDR3 SDRAM PC3-6400 – PC3-12800 400MHz, 533MHz, 667MHz, 800MHz Rambus DRAM Direct competitor to DDR PC600, PC700, PC800, PC1066 400 or 533MHz

RAM Packages SIMMs (Single Inline Memory Module) Two sizes: 30-pin SIMMs and 72-pin SIMMs Need to be installed by groups of two or four which is known as banks. Used in FPM and EDO RAM DIMMs (Dual Inline Memory Module) Used by SDRAM and DDR SDRAM SDRAM – 168-pin DIMM DDR SDRAM – 184-pin DIMM SO DIMMs (Small Outline DIMMs) use for laptops SO DIMMS – 200 pins

RIMMs (Rambus Inline Memory Module) Use for RIMM Uses a special stick called a CRIMM (continuity) All slots must be filled 160 pins

Install RAM in a PC Every time you load a program, it takes up some of your RAM. When you run out of real RAM on your PC, your PC will use a special part of your hard drive, called the swap file, as if it were RAM. This process is called using virtual memory. Using virtual memory too much causes the system to slow down and the hard drive to thrash. These symptoms are the primary signs that

Unless a RAM chip is labeled, it is impossible to tell its capacity simply by looking at it. Make sure that you have the right speed of RAM for your system. Always handle RAM very carefully to prevent ESD. Use the RAM count at bootup as your primary test to determine whether the PC recognizes added RAM.

Review Questions The chip is the primary interface between the CPU and RAM. Eastbridge Southbridge Northbridge RAMBUS

Review Questions Which of the following statements is true about RDRAM? It uses dual-channel architecture. It offers speeds ranging from 200 MHz to 600 MHz. It is less expensive than SDRAM. It is used by AMD but not Intel processors.

Review Questions Which of the following SDRAM speeds would not work with a 100-MHz motherboard? 66 MHz 100 MHz 133 MHz 200 MHz

Review Questions Which of the following is a valid package size for desktop RDRAM RIMMs? 160-pin 172-pin 184-pin 200-pin

Review Questions What package does DDR-SDRAM use for desktop PCs? 30-pin 72-pin 168-pin 184-pin

Review Questions Why is SDRAM faster than regular DRAM? It makes two processes per clock cycle. It runs synchronously with the system clock. It uses dual-channel architecture. It has fewer pins, resulting in fewer corrupt bits.

Review Questions What is another name for DDR400? PC200 PC400 PC1600

Review Questions Joaquin wishes to upgrade the DDR RAM in his system with DDR2. Angela says he can’t because sticks of DDR2 won’t fit in the motherboard slots that currently hold Joaquin’s DDR RAM. Ben says he can use DDR2 in his system, but won’t see any speed benefit because the motherboard only supports DDR. Who is correct? Angela is correct. Ben is correct. Both Angela and Ben are correct. Neither Angela nor Ben is correct.