This guide is designed to  help a lay-person such as myself to visually indentify a ram module, a physical stick of memory that goes into a computer.You have the codes for RAM speed here.You can also calculate the size in MB,density structure,and if is jedec standard RAM.

This info is not copywrited or a trade secret, its just very difficult to locate.    please feel free to print the guide and store it with any old memory you might decide to sell or use later to assist in identification, or to get specs for your listing-gem 91533

The responsibility for ordering the correct RAM is and allways will be the responsibility of the buyer.  

I recommend you visually inspect and verify the RAM you recieve is the RAM you ordered before you install it to any computer, to avoid damage to the RAM and or the machine:And pull a stick from the computer to verify the speed is going to be compatable with the memory already in the machine(refer to last paragraph

 

All ram looks pretty much the same, and yet there are so many types and speeds. They have different pin counts slot configurations and memory module configurations, each type and configuration has different names which can add to the confusion.  To keep this simple for lay-people I am going to skip all that...it is covered quite well in other guides designed to help people identify the requirements of their individual machines .

There are two general assumptions I am going to start with-

        ( and there are exceptions to both-but I am ignoring them for the purpose   of   simplicity )

1- branded ram  is generally what it says it is on the warrantee sticker.

    (this "brand-name" usually will have a paper sticker with the product code

     number printed on the tag and on the board-they should match and you can

     usually research the specifics at the brand-name company website)

2- unbranded (or generic) ram is almost always constructed using Samsung modules onto boards not stamped with any identification for the maker.

You will need to know that the modules are catagorized by density (number of megabits that the chips inside can store) and that the capacity of the stick is usually the number of modules times the density of the modules divided by 8.

    an example : you read a module at 128Mb (bits,not bytes)

                                                   times    8 modules on the board

                                                  equals    924Mb           

    divided by 8(8bits per byte) equals    128MB

*There is an exception where there are an odd number of modules on the board the last module is for parity control and is not counted.

Since I am assuming you are looking at an unbranded stick of ram and that stick has Samsung memory modules- this is how to read the product code on that memory module.

*to keep us on the same page the memory modules are the black rectangular or square objects - they take up most of the board, on one side or both sides of the board...the identifying number is the largest number printed on that board,it has a hyphen towards the end followed by a combination of 4 letters or numbers.

the format for the  code is:

     1  2   3    4        5    6  7  8   -   9  10     11

     !   !    !     !         !     !  !   !        !    !        !

     K 4   X   XX     XX   X X  X  -   X  X    XX

 

*1 (1st digit) SAMSUNG Memory : K

*2 (2nd digit) DRAM : 4

*3 (3rd digit) DRAM Type : 

        B : DDR3 SDRAM

        T : DDR2 SDRAM

        H : DDR SDRAM

        S : SDRAM

*4 (4th and 5th digit) Density

      28 : 128Mb

      56 : 256Mb

      51 : 412Mb

      1G : 1Gb

      2G : 2Gb

      4G : 4Gb

*5(6th and 7th digit) Bit Organization

      04 : x 4

      06 : x 4 Stack

      07 : x 8 Stack

      08 : x 8

      16 : x 16

      26 : x 4 Stack(JEDEC Standard)

      27 : x 8 Stack(JEDEC Standard)

*6(8th digit) # of internal banks

       3 : 4 Banks

       4 : 8 Banks

       5: 16 Banks

*7(9th digit) Interface (VDD and VDDQ)

       6: SSTL (1.5V,1.5V)

       8: SSTL-2(2.5v,2.5v)

*8(10th digit) Revision

      M : 1st Gen

      A : 2nd Gen

      B : 3rd Gen

      C : 4th Gen( following generations in alphabetical order)

*9(11th digit-follows hyphen) Package Type

      T : TSOP2 (400mil x 875mil)

*10(12th digit-2nd digit after hyphen) Temperature & Power

      C : Commercial Temp(0deg C - 85deg C) & Normal Power

      L : Commercial Temp(0deg C - 85deg C) & Low power

*11(13th and 14th digit-last 2 digits) Speed :

  SDRAM 50=5ns(200Mhz cl3

                55=5.5ns(183Mhz  cl3)

                60=6ns(166Mhz cl3)

                70=7ns(143Mhz cl3)

                75=7.5ns(PC133 133Mhz cl3)

                80=8ns(125Mhz cl3)

   DDR     CC=DDR400(200Mhz @cl3,tRCD=3tRP=3)

                C4=DDR400(200Mhz @ cl3)

                B3=DDR333(166Mhz @ cl2.5)

                A2=DDR266A(133Mhz @ cl12)

                B0=DDR266B(133Mhz @ cl2.5)

                A0=DDR200(100Mhz @ cl2)

DDR2      CC=DDR2-400(200Mhz @cl=3)

                D5=DDR2-533(266Mhz @ cl4)

                E6=DDR2-667(333Mhz @ cl5)

                E7=DDR2-800(400Mhz @ cl5)

                F7=DDR2-800(400Mhz @ cl6)

DDR3      F7=DDR3-800(400Mhz @ cl6)

                F8=DDR3-1066(533Mhz @ cl8)

                G8=DDR3-1066(533Mhz @ cl8)

                G9=DDR3-1333(667Mhz @ cl9)

                H9=DDR3-1333(667Mhz @ cl9)

                H0=DDR3-1600(800Mhz @ cl9)

                J0=DDR3-1600(800Mhz @ cl9)

 

To Recap  3rd digit is class of ram , 4th and 5th digit is capacity(Mb) , the 6th and 7th digit are low or high density( 04 is considered high density because more chips in the module are on each bank+ 08 and 16 are considered low density because there are fewer chips on each bank , and the last 2 digits are speed...each step up represents advances in technology(different ram classes are not compatible and will have different pin configurations)The general rule is that faster memory will match speeds with slower computers but computers require a minimum speed and will not run on slower ram(The exception here is that some computers are built in transition periods where faster ram is becoming available are set up with the slower memory but will accept and utilize the next step up in memory.Keep in mind that your machine will run at the rate of the slowest memory installed when you decide whether to add or replace memory. And keep in mind every machine has a maximum capacity for RAM.

 

I hope this has been helpful and educational- the best consumer is an informed consumer- when i needed this information it was extremely difficult to find.

pls feel free to doublecheck my info- it is from Samsung Global Semiconductor business products - look under related documents for: pdf  ddr product guide

pity I cannot include their website here due to the rules

thanks for your time

sincerely gem9153