RAM (Random Access Memory)

  • Visipro DDR 128Mb PC266 Unbuffered.
  • Visipro DDR2 512MB PC3200 ECC Registered.
  • Visipro DDR2 1GB PC3200 Unbuffered.
  • Visipro DDR SODIMM 256MB PC2700 Unbuffered.

Information above explain the device specification in computer system, called Memory or RAM.

Memory called as RAM, abbreviation of Random Access Memory. Memory is for saving temporary data. Memory works with saving and supply an important data that process become an information. Thats why the function of capacity is important thing in memory. increasingly capacity, data that can be saved and supply more increased, it makes processor works faster.Data supply to RAM is originate form Hard Disk, an equipment that can save permanent data.

Illustration of Memory operation

Operation of Processor in Computer System


While turn on the computer , Processor is first device that works. Processor function as data prosessor and request data form storage, namely Hard Disk (HDD). It means the data send form Hard Disk after the request of Processor.

In fact this action is hard to do because of the technology difference between Processor and Hard Disk. Computer own is pure digital component, that will process data very fast (high Bandwith P4 is 6,4 GB/s with FSB 800Mhz). Whereas Hard Disk a part of the technology is slow mecanism appeal with digital (Bandwidth of Transfer Rate HDD Serial AT about 150 MB/s). Theoretical speed of Procesor 46x faster that HDD. Means if Processor search HDD supply data will afoot acute "Bottle Neck".

To solve the reaction, needs a Primary Memory device or called RAM. RAM or Random Access Memory function is to support needs of Processor in supply data "shock wave". RAM function as Digital HDD, because all RAM component is using digital technology. With RAM, Processor not necessary to wait data ending from HDD. Now in RAM DDR2 have 3,2 GB/s (PC400) Bandwidth, in order not to disturb the supply, now Motherboard used Dual Channel technology that redouble bandwidth two fold with increase the architecture become 128-bit. It means, 2 piece DDR2 in Dual Channel can supply fit total to Processor ((3,2 GB/s x Dual Channel = 6,4 GB/s). 

An important factors on RAM.
  • Type describe variant RAM depend on use technology, like SDRAM, DDR or DDR2. Known as "interface", For example Visipro DDR 256Mb PC266 means using DDR technology.


  • Picture an important factors in RAM

  • Capacity describe how big is the capacity data storage of RAM in Gigabyte (GB) or Megabyte (MB) denomination. Capacity is main factor in RAM that function as data storage. For example Visipro DDR2 512Mb PC4300 means have 512 Megabytes capacity.
  • FSB or Front Side Bus, is data line between Processor and RAM in Megahertz denomination. denomination of FSB Processor and RAM must have the same number to gain an optimal transfer the data [see : Dual Channel RAM table]. For example Visipro DDR2 256MB means have 400Mhz FSB (PC4300 divine 8 byte).
  • Funtion , describe RAM function, like Unbuffered (used on desktop), ECC or Registered (both used in Server). [see on what is Unbuffered, ECC dan Registered segment ?] Unbuffered is RAM type that used by common computer, ECC (Error Correction Code) usually used on Workstation Computer / Low End Server & ECC Registered used in Medium to High End Server. For Example DDR2 1GB PC4300 ECC Registered means have ECC Function Registered on the module. Bandwith is constitude a large data that transfered or process ini 1 second (MB/s atau Megabyte per-secon). Commonly now RAM DDR/DDR2 attach bandwidth on RAM module. Bandwidth reach by multiple FSB x Architechture. RAM Architechture is 64-bit (8byte), so if DDR PC266 have FSB 266 MHz equal with 266 MHz x 8 byte = 2100 MB/s. It means that DDR PC266 (FSB) equal with DDR PC2100 (Bandwidth). For example : Visipro DDR2 512MB PC4300 means have bandwidth 4300MB/s.

  • Example Bandwidth Table


  • Amount of IC describe how many is the chip (IC) that tide unto RAM module. A bit of IC, many of density (capacity /IC). Commonly is 4, 8, 16 IC (on standard RAM ). On RAM ECC have IC 9 & 16, and in ECC Registered have IC 9 & 16 add 1 ICC function as Registered. For example Visipro DDR 256MB have 4, 8 atau 16 IC. Use 4IC means density of IC = 64MB, 8IC = 32MB & 16IC = 16MB.
  • * IC tide on one side piece of RAM called Single-Side (4, 8, 9 IC), if tide 2 pieces of RAM called Double-Side (16 & 18 IC).

    A configuration table of IC
What is SDRAM, DDR and RDRAM ?

  • SDRAM (Synchronous Dynamic RAM) - Type of RAM produced in 1996. SDRAM is a legend RAM, and quite long survive in computer system development. SDRAM have a Synchronous Dynamic term, that capability of RAM to match the clock with  processor clock. if RAM clock and processor equal, then computer system well balanced because of both current data fluent stroll. SDRAM technic caracteristic have 168-pin, 3.3V & FSB 100/133 MHz. Now SDRAM is not use  by computer platform, last used in Pentium4 first generation version. SDRAM types : SDRAM 32, 64, 128, 256, 512MB PC100/133.

  • DDR (Double Data Rate) - Type of RAM that continue development from SDRAM technology. DDR produced in 2000. The first DDR made as main competitor of RDRAM memory that produced by Intel anda Rambus early Pentium 4 generation, and now become mainstream platform of computer. Technic characteristic of DDR is 184-pin, 2.5V & FSB 266/333/400 MHz. Theoritical DDR have twice ability to process data than SDRAM, because ability to carry 2 bit in 1 of its clock- Compare with SDRAM only have 1 bit. DDR still used in various platform, like Pentium 4 & Celeron D and will replaced with DDR2 technology. type of DDR : DDR 128, 256, 512, 1.024MB PC2100/2700/3200.

  • DDR2 (Double Data Rate Generation 2) - DDR2 is next generation of DDR in variant fitur restoration, like using IC BGA (Ball Grid Array) fire-proof and have high density and high FSB. Technical characteristic of DDR2 is 240-pin, 1.8V & FSB 400/533/667/800 MHz. DDR2 have a high capacity than DDR, where can reached 2GB /module. Now on DDR2 will be a standard for all platform Intel 2006 and forth. type of DDR2 : DDR 256, 512, 1.024MB PC3200/4300/5300/6400.

  • RDRAM (Rambus Dynamic RAM) -  The first Typeof made in 1999. RDRAM is RAM that use a new tchnology that develop by Rambus company. RDRAM have bandwidth ability equal with bandwidth need on processor Intel Pentium 4. First Dual Channel technology known by RDRAM. RDRAM have Serial type processing, compare with SDRAM & DDR that produced as Paralel. Technical characteristic of RDRAM is 184-pin, 2.5V & FSB 800, 1.066 with architecture 16-bit (2 byte). Now all type of RDRAM not use in computer because the price is too expensive and the performance is equal with DDR/DDR2. Type of RDRAM : RDRAM 64, 128, 256, 512MB PC800/1.066 MHz.


  • Why it called as RAM ?



    Picture Memory Variation 

Mentioning RAM to different with another variation of memory in computer, there is exist some variant in their system.

RAM (Random Access Memory), as the name means Memory that can access disordered. It means the data can be access more faster, because of memory controller towards directly to saved bit data then access it.

Some variation of on Computer:
  • Cache Memory, memory exist on Processor.
  • Cache Buffer, memory exist on  Hard Disk.
  • Flash Memory, memory non-volatile that used as external/internal storage on certain device, like PDA.
  • CMOS (BIOS), a memory on Motherboard that function as id in each device that installed on that MB.

What is Dynamic RAM ?

A Dynamic RAM is an integrated circuit (chip) variation that used on RAM. Dynamic RAM only save data if there is a power that refresh it. If the power is lost, saved data automaticly lost. thats why needs a continually power to supply that RAM in order to stroll as function. it called as Volatile.
Converse of Dynamic RAM is Static RAM (SRAM). Static RAM usually used on Cache Memory & Cache Buffer. Static RAM is expensive because stroll faster in transfering data.



Picture Static RAM (Cache Memory on Processor)

What is Unbuffered, ECC dan Registered ?



Picture DDR ECC Registered

  • Unbuffered describe RAM that used in desktop platform. Unbuffered is RAM ‘adjusted type', the terminology not use anymore. Commonly all an adjusted type RAM (DDR or DDR2) is Unbuffered type.
  • ECC is Error Correction Code, function that can checking error 2 bit data, and correction dan 1 bit from error data. ECC analogycal as Security Officer that head for all guest to enter a building. ECC usually used in workstation computer platform or low-end server.
  • ECC Registered is a RAM function that handling data in high capacity, like server. Registered analogycal as a “power-steering” function on car, where the helm of car light enough even the wheel is hard cycling.

What is the difference between Unbuffered, ECC and Registered physical?
  • Unbuffered, ECC and Registered physicaly different. Commonly RAM consist of 4, 8 or 16 piece of IC.
  • ECC consist piece of IC that can be divide with number 3 or 5. ECC can be seen in amount of the IC, that is 5 IC (can divide by 5), 9 IC (can divide by 3) or 18 IC (can divide by 3).
  • Registered usually have one chips in horizontaly tide. This Chip function as registerered.
What is Bandwith Memory ?

Bandwitdh is mark show a lots of data that can be transfered in 1 second. Denomination of Satuan Bandwitdh is Mb/s. Bandwidth show a real performance of RAM.
Theoritycal Bandwith count by this formula:



Commonly in RAM DDR, FSB value write rare and change with bandwidth value. architecture of RAM (DDR/DDR2) basicly is 64-bit (or 8 byte). RAM Dual Channel mode means have 64-bit x 2 = 128 bit architecture or 16-byte. Dual channel made bandwidth RAM twice fold bigger.

Example :

  • DDR Visipro 256Mb PC266 write as PC2100 (Bandwidth dari PC266), multiple from 64-bit (8 byte) x 266 MHz = 2.128 MB/s ~ rounding off 2.100.
  • DDR Visipro 128Mb PC333 write as PC2700 (Bandwidth dari PC333), multiple form 64-bit (8 byte) x 333 MHz = 2.664 MB/s ~ rounding off  2.700.
  • DDR Visipro 512Mb PC400 write as PC3200 (Bandwidth dari PC400), multiple from 64-bit (8 byte) x 400 MHz = 3.200 MB/s.
  • DDR2 Visipro 1GB PC533 write as  PC4200, multiple from 64-bit (8 byte) x 533 MHz = 4.264 MB/s ~ rounding off  4.200.
  • DDR2 Visipro 1GB PC667 write as  PC5300, multiple from 64-bit (8 byte) x 667 MHz = 5.336 MB/s ~ rounding off  5.300.


Picture calculate of Bandwidth & Dual Channel



What is Dual Channel RAM ?

Dual Channel RAM is one motherboard fitur that enable to bandwitdh RAM escalation wider. With Dual Channel, available bandwith twice fold bigger than one piece of RAM instalation (multiple architechture value). Consumption Dual Channel needs 2 pieces of equal RAM, and now is apply to platform DDR PC3200, PC4200 & PC5300. Formerly Dual Channel known as RDRAM.

With dual channel, bandwith that can supply by DDR PC3200 as big as 6,4 Gb/s, while using single channel only 3,2 Gb/s.

 
Gambar RAM DDR2 Dual Channel & Slot DIMM pada Motherboard

Dual Channel is a chipset Motherboard technology – not in RAM. Each DDR that used configured on  Single mode or Dual Channel. Formerly Dual Channel configuration needs 2 pieces similar of RAM (in type, capacity, FSB, and type of IC). Now on there is a technology named by Intel Flex Memory Technology on platform Motherboard Intel where allow two types RAM not similar each other (type must be similar) to tide on Dual Channel configuration.

SODIMM (Small Outline Dual In-line Memory Module)

SODIMM is type of RAM used in Notebook. SODIMM have interface, technology & specification more or less with ordinary RAM, in small and same size. SODIMM terminology is point in slot motherboard in tide RAM, In PC Motherboard named DIMM.

SODIMM is important following a rapid development of Notebook used by user. Last technology in SODIMM is DDR & DDR2 like PC technology.


Picture DDR DIMM and DDR SODIMM

Groups of RAM Module

There is Modul RAM groups depend on production type :


Picture Module RAM
  • Original modules

  • Original Modules is RAM that produced by a famous variant vendors where also produced an IC. Usually used Major Brand IC. usually using a quality or a standard PBC (cost issue). Example : Hynix original, Micron original, Samsung original.

  • Major Brand modules

  • Major Brand Modules produced and assembly by certain Manufacture depend on the orders of the vendors. Usually used Major Brand IC, and using a quality PCB. Example: Visipro, Kingston, Mushkin, Buffalo etc.

  • OEM modules

  • Not use an IC Major Brand (1st Grade is possible), sometimes  using a quality or a standard PCB. OEM give brand on their module, while RAM is made by onother vendor. Example : TwinMos, Apacer, V-Gen.


Quality IC (Integrated Circuit) used in RAM



Picture Hynix IC brand.

  • Major Brand DRAM

  • IC produced by known manufacture and caring they own brand name (like micron, infineon, Hynix, Samsung, etc) of the IC. The most quality of Major Brand is when process of Wafer Silicon cuts until certain IC is not damage. IC Major Brand is best quality of IC. Example: Visipro, Kingston, Mushkin, Corsair.

  • 1st grade DRAM

  • Only wafer produced by manufactur, While IC Made by OEM Company caring they own brand name. This IC is hesistating quality, because the wafer isn't come form a good manufacture. Sometimes 1st Grade IC have name and same quality with Major Brand, this IC impassable process testing. Example : Spectech, TwinMos, Apacer.

  • 2nd grade DRAM

  • Part of this IC is error/damage while testing (error of wafer cut). It's used in device low-end like household equipment, toys, HP, etc. There is RAM brand using this IC to gain a low price.


Karakteristik sebuah Modul RAM

  • Printed Circuit Board (PCB). Usually RAM have PCB with 6-layers.
  • SMT. SMT is electronic supporting component like resistor, capasitor, etc.
  • Notch. is cavity lock of RAM so can go in the correct slot.
  • Pin. bases od RAM contact with Motherboard slot.
  • ICs (Integrated Circuit). Electronis Component Memory.
  • Serial Presence Detect (SPD). is a small IC to save a configuration data in RAM.
  • Circuit. Electric lines / data connect to RAM component items.



Picture Module RAM characteristic.
RAM on Motherboard

In Motherboard platform RAM put in specific slot named DIMM (PC Desktop) or SODIMM (Notebook, Laptop). DIMM is abbreviation from Dual In-Line Memory Module, and abbreviation from SODIMM Small Outline - DIMM.

On Motherboard system RAM characteristic is depend on use chipset, Example chipset Intel 865G oblige motherboard using DDR PC3200 Dual Channel, then platform Motherboard system will supply corrent type of DIMM slot.

Commonly motherboard supply Dual Channel configuration on slot, In Motherboard ATX/BTX Desktop available 4 slot-channel, Motherboard micro-ATX/BTX available 2 slot-channel, Motherboard Notebook available 1 & 2 slot-channel (2 on hand) and several type of Motherboard Server available more than 4 slot-channel.

Several DIMM configuration:

  • RAM DDR Unbuffered using slot DIMM 184-pin 2.5V (commonly in Intel chipset 845xx, 865xx & 915xx).
  • RAM DDR ECC using slot DIMM 184-pin 2.5V (commonly in Intel chipset 875P, 925X).
  • RAM DDR ECC Registered using slot DIMM 184-pin 2.5V ECC Registered (commonly used in several type of Motherboard Server).
  • RAM DDR2 Unbuffered using slot DIMM 200-pin 1.8V (commonly in Intel chipset 925X, 945xx)
  • RAM DDR2 ECC using slot DIMM 200-pin 2.5V (commonly in Intel chipset  955X dan 975X)
  • RAM DDR Unbuffered using slot DIMM 184-pin 2.5V (commonly used in several type of Motherboard Server).



Picture Motherboard & RAM Configuration

Terminology of RAM complement

  • CAS Latency (CL). CAS abbreviation from Column Address Strobe Latency, is time limit while bit data moved from row to column in storage matriks Memory. Commonly DDR have CL 2.5 and DDR2 CL 4. CL setting by BIOS, and it used as Overclocking & Tweaking technique.
  • Serial Presence Detect (SPD). Small Chip contain ana ifnormation of RAM characteristic. SPD means as BIOS in RAM that save all data and RAM configuration.
  • Double Side RAM. A RAM module have two side PCB. Usually Amount IC in RAM is 16 and 18.
  • Internal Trace Layer. Each PCB have a certain layer. To addopt length of circuit on RAM module then have to placed in each layer. It function as divider between the circuit.

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