14.2.1 SIMM Identification

Speichermodule identifizieren

What is EDO RAM?

They stand for Extended Data Out. In theory when EDO SIMM are used with computer that supports EDO, the memory speed performance goes up around 10-20% But the 72 pin EDO didn't really catch on and there are lots of leftover EDO SIMMs.

Some adverts for 72-pin SIMMS 16 or 32MB, quite cheap _but_ they're always listed as EDO.

They are cheap because they were overproduced then, and not many non EDO system will work with EDO SIMM correctly so they are somewhat unpopular among the older non EDO systems.

If EDO won't work on your Computer, Extension, Printer you are looking for FP (Fast Page) the older design that are more compatiable with non EDO systems. Parity chip are not needed on your FP SIMM, and EDO never used parity chip.

SIMM Identification

This file describes the presence detect system for 72-pin SIMMS in any Hardware.

Some presence detect pins, 67-70, tell the system the size and speed of the SIMM Module. Using good ESD practices and a digital volt/ohm meter measure the resistance between pins 67-70 and 72.

The pins are numbered sequentially, starting from the notched end, i.e., pin 72 is the pin closest to the un-notched end of the SIMM Module.

Use caution to not put the meter leads on pins other than those used for presence detect. Depending on the voltage used by the DVM, damage to the SIMM could occur!

"I" indicates infinite resistance to pin 72. "G" indicates <10 ohms to pin 72 (typically a short-circuit).

For SIMMs that do -not- have the Presence Detect pins connected, it is possible to solder small wires from the appropriate pins of the SIMM to pin 72 of the SIMM in order to have the Hardware recognize the SIMM Module.