This page is maintained by Thomas Unger
and part of the Amiga computers related kickstart archives.
DRAM stands for Dynamic Random Access Memory. The charts below provide information for major packages of DRAM chips.
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