Dynamic Random Access Memory (DRAM)


DRAM Part Number Chart SIMM


This page is maintained by Thomas Unger and part of the Amiga computers related kickstart archives.
All brands, trademarks and copyrights on this page are owned by their respective owners.
Last updated: 2004-01-23


  1. DRAM Package Information
  2. How to decrypt the OnChip Code


1. DRAM Package Information


DRAM stands for Dynamic Random Access Memory. The charts below provide information for major packages of DRAM chips.

Dual-in-line Package

Dual-in-line Package
Zig-Zag-in-line Package

Zig-Zag-in-line Package
Small Outline Package

Small Outline Package
Shrink Small Outline Package

Shrink Small Outline Package
Thin Small Outline Package Type 2

Thin Small Outline Package
Small Outline J-Lead

Small Outline J-Lead


DRAM Part Number Chart SIMM


2. How to decrypt the OnChip Code


In the late 1980s the most common DRAM types were PM (Page Mode) and FPM (Fast Page Mode). In early 1990s the most common types were FPM and FPM with EDO (Extended Data Out).

Generally each manufacturer uses his own scheme to mark memory chips. However, a simple algorithm can be used in most cases to determine the exact type of chip.

Usually the number starts with two or three characters which are specific to the manufacturer. For an FPM, nibble, SC or EDO chip the rest of the sequence is usually up to 16 Mbit chips built up more or less the same : first an indication of the manufacturer, total memory and refresh address range is given, then the number of bits per chip, then the mode of operation terminating with the memory speed (for manufacturers specific part number code decoding see the Part Number Chart).

Format :        XXX AA BB CC D -EE

XXX: Manufacturers Identification Code: 

                MB    Fujitsu             GM    Goldstar/LGS
                HM    Hitachi             HY    Hyundai
                MT    Micron              M5M   Mitsubishi
                MCM   Motorola            uPD   NEC
                MSM   OKI                 MN    Panasonic/Matsushita
                KM    Samsung/SEC         K     Samsung/SEC  (new code)      
                LH    Sharp               HYB   Siemens/Infineon 
                TMS   Texas Instruments   TC    Toshiba    
AA : Total Number of Megabits:

                 1 :   1 MBit
                 4 :   4 MBit
                16 :  16 MBit/4k  Refresh
                17 :  16 MBit/2k  Refresh
                18 :  16 MBit/1k  Refresh

BB : Internal Organization (Data Width): 

                10 :   1 Bit  (1 MBit Chips: 0 = 1 Bit) 
                40 :   4 Bit
                80 :   8 Bit
                16 :  16 Bit

CC : I/O Mode:   0 :     Fast Page Mode (FPM)
                 1 :     Nibble Mode (NM)
                 2 :     Static Column Mode (SCM)
             3 - 9 :     Fast Page Mode mit Extended Data Out (EDO)

D :  Package Information: 

                  J:     SOJ- package.
                  T:     TSOP Type-II package

EE : Access time in nano seconds. Sometimes the zero is omitted. 
     In that case the number should be multiplied by 10 so that the 
     speed falls into the 30 to 150ns range.

Examples:  TC51 1 0 00 -60  --> Toshiba,  1MB, 1bit (1Mx1), FPM, 60ns
           HYB51 4 4 00 -60 --> Siemens,  4MB, 4bit (1Mx4), FPM, 60ns
           HM51 18 16 0 -6  --> Hitachi, 16MB/1k refresh, 16bit (1Mx16),FPM, 60ns 


DRAM Part Number Chart SIMM


[ back to main ]