Memory chip numbers

Dram Numbers

For devices of 1Mbit and over :

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

Usually the number starts with one or two characters and a few digits which are specific to the manufacturer. For an FPM, nibble, SC or EDO chip the rest of the sequence is usually buit up more or less the same : first an indication of the 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.

Format : ----AA B CC -J DD--

AA : Total number of megabits. 1=1Mb, 4=4Mb, 16=16Mb/4k refresh, 17=16Mb/2k refresh.
B  : Data width. (1,4,8)
CC : I/O mode : 00 = Fast page mode (normal memory)
                01 = Nibble mode
                02 = Static Column mode
                03 - 10 = Extended Data Out mode (EDO)
DD : Access time, should be 30 to 80ns. Sometimes the zero is omitted. In that case the numerb should be multiplied by 10 so that the speed falls into the 30 to 80ns range. (NOT FOR SDRAMS !)


Examples :

1) HYB51 4 4 00 BJ -60  (8x)

The HYB51 denotes it is a Siemens device
The first 4 denotes it is a 4 megabit chip with 2k refresh.
The second 4 denotes the chip has 4 bits data width.
The 00 denotes it is a fast page device.
The character B denotes the production line or revision.
The J denotes SOJ housing (standard)
The -60 indicates the speed of 60ns.

The chip is thus 1Mx4 60ns FPM.
If there are 8 such chips on a 72pin simm module, then we have 1Mx4x8=1Mx32.
This is a 4Mbyte Fast page module with no parity.


2) HYB51 17 4 00 BJ -70  (2x)

The HYB51 denotes it is a Siemens device
The 17 denotes it is a 16 megabit chip with 2k refresh.
The second 4 denotes the chip has 4 bits data width.
The 00 denotes it is a fast page device.
The character B denotes the production line or revision.
The J denotes SOJ housing (standard)
The -70 indicates the speed of 70ns.

The chip is thus 4Mx4 70ns FPM.
If there are 2 such chips on a 30pin simm module, then we have 4Mx4x2=4Mx8.
This is a 4Mbyte Fast page 30 pin module with no parity.



3) M5M4 17 4 05 CJ -6 S  (16x)

The H5M4 denotes it is a Mitsubishi device
The 17 denotes it is a 16 megabit chip with 2k refresh.
The 4 denotes the chip has 4 bits data width.
The 05 denotes it is an EDO device.
The character C denotes the production line or revision.
The J denotes SOJ housing (standard)
The -6 indicates a speed of 60ns.

The chip is thus 4Mx4 60ns EDO.
If there are 16 such chips on a 72pin simm module, then we have 2x4Mx4x8=8Mx32.
This is a 32Mbyte EDO module.


4) GM71C 17 4 00 CJ 6 (8x) and GM71C 4 1 00 CJ 60 (4x) 

The GM71C denotes it is a Goldstar device

Data chips :
The 17 denotes it is a 16 megabit chip with 2k refresh.
The 4 denotes the chip has 4 bits data width.
The 00 denotes it is a FPM device.
The character C denotes the production line or revision.
The J denotes SOJ housing (standard)
The -6 indicates a speed of 60ns.

The data chip is thus a 4Mx4 FPM 60ns device.

Parity chips :
The 4 denotes it is a 4 megabit chip with 2k refresh.
The 1 denotes the chip has 1 bit data width.
The 00 denotes it is a FPM device.
The character C denotes the production line or revision.
The J denotes SOJ housing (standard)
The -60 indicates a speed of 60ns.

The parity chip is thus a 4Mx1 FPM 60ns device.

If there are 8 data chips and 4 parity chips on the module, then we have
4Mx4x8 + 4Mx1x4 = 4Mx32 + 4Mx4 = 4Mx36.
This is a 16Mbyte FPM module with parity.






The following table lists some current and older FPM DRAM devices and common manufacturing part numbers. If you got a memory module and you don't know what's the exact memory type, you can always determine the kind of chips are used on the memory module. If you know the kind of chips used, you can determine the type of memory module as in the example above.

Module Numbers

The following table lists the common module descriptions and numbers.
For examble if someone talks of a 1Mx32 module and you don't know exactly what
type of memory module is talking about, you can always find it out in the next table.

• THINK MAN/WOMAN THINK BEFORE DO IT ...
• COME BACK