2.871 bytes

Service Hints & Tips

Document ID: GSMH-3ACEFL

PS/1 - SIMM Identification

Applicable to: World-Wide

30-Pin Memory SIMMs:
30-pin memory SIMM size and speed can be difficult to identify. By looking at the numbers on the SIMM chips, you can attempt to identify the size and speed of the SIMM. The size of the SIMM is generally imbedded in the chip part number and the speed generally follows the number.

For example: xxx256xx - 8 (x can be any number or letter or letter) would be a 256K SIMM and have a speed of 80 ns xxxx1000x - 7 would be a 1 MB SIMM and have a speed of 70 ns xxxx256x - 15 would be an unsupported SIMM since it has a speed of 150 ns There are many variations to this. Consult the SIMM manufacturer documentation to identify SIMM values when you are unsure of the SIMM value in the system.

72-pin Memory SIMMs:
The 72-pin memory SIMM for 486SX, 486DX, and 486DX2 system boards are usually marked with a label that shows the size and speed (for example, 1mx36, 7 ns). SIMMs that are not explicitly labeled cannot be identified other than by part number. Consult the SIMM values when you are unsure of the SIMM Value in the system.

Search Keywords

Hint Category


Date Created


Last Updated


Revision Date



IBM Aptiva

Product Family


Machine Type

2133, 2155, 2168




Retain Tip (if applicable)

Reverse Doclinks
and Admin Purposes