Test Results

1. Q. What do the values from the Relative Refresh and Relative Spikes tests mean?
   A. These are relative or comparative values given during our data retention tests. The Relative Refresh provides a value for the ability of the memory module to retain data between refresh cycles, while the Spikes figure gives a value on how well a module can sustain voltage spikes before data loss occurs. See Section 5.3.3 in your SIMCHECK II Manual for further information.
   
   
2. Q. What does the "Device Type Warning" message mean?
   A. This message indicates that the tester has detected a difference in the architecture of the module when compared to the national standard. It does not necessarily mean that there is a problem with your memory device. This message is meant to inform the user that the tested device may not be a drop-in replacement for modules that meet the national standard. Additional information will follow this message, giving specific details as to what difference the tester found. Some differences include the detection of Assymetric 4K refresh or the detection of shorted RAS lines (RAS0 to RAS2 and RAS1 to RAS3). See the questions below for further information on these messages.
   
   
3. Q. What is the difference between 2K and 4K refresh and can SIMCHECK II support these refresh varieties?
   A. The DRAM memory array is arranged along a matrix of Rows and Columns. Each memory cell is accessed by multiplexing first the Row address and then the Column address. The row is the main access, and all the cells in a row are refreshed when the row is accessed. When the number of rows is equal to the number of columns, we say that the DRAM is symmetric, when the rows number is different than the columns number, we say that the DRAM is asymmetric. Asymmetric DRAM has the advantage of reduced power consumption, as less refresh is required. A symmetric 4M device with 11 address lines for both rows and columns has 2K refresh. An asymmetric 4M device with 12 rows and only 10 columns is called 4K refresh. SIMCHECK II automatically detects the refresh type (1K, 2K, 4K and the new 8K). Since historically symmetric devices were first used, SIMCHECK II regards symmetric devices as default, and puts a structure note message when an asymmetric device is encountered.
   
   
4. Q. What does the message RAS0 shorted to RAS2 (or RAS1 shorted to RAS3) mean?
   A. The tester has detected the Row Address lines as being shorted together as opposed to having them operate independently. This does not render the module as defective as it will still work in many machines, but it may cause it to not function in motherboards that require independent signals.
   
   
5. Q. After just receiving my SIMCHECK II PLUS, why am I getting constant memory errors when testing my 30-pin or 72-pin modules, and why does the tester prompt for testing only Sync modules?
   A. The SIMCHECK II PLUS is comprised of two pieces. The base tester SIMCHECK II and the additional test adapter Sync DIMMCHECK 168. In packaging, the Sync DIMMCHECK 168 is connected to SIMCHECK II, and when left in this fashion, SIMCHECK II will only work with 168-pin memory (the display will flash "Sync DIMMCHECK 168").
   
   To test 30-pin or 72-pin modules, you will need to remove the Sync DIMMCHECK 168 adapter from the base unit. Removal is performed by TURNING OFF SIMCHECK II and working the adapter upwards while gripping it on its left and right side. When returning to 168-pin testing, TURN OFF SIMCHECK II and reconnect the Sync DIMMCHECK 168.
   
   
6. Q. What are parity emulation chips? What does the "p" mean on the display 1Mx8p or 2Mx32p?
   A. Parity emulation chips are logic devices that provide parity information by being tied directly to your module's data lines, and thusly, bypassing the true parity function. It is important to note that these devices are NOT memory chips, therefore modules detected as having these chips will be identified with the "p" suffix.

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