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SIMCHECK II Plus Structure Analysis for SDRAM
The SIMCHECK II has a built-in feature for analyzing the structure of an SDRAM device. Typically, this feature is used by SIMCHECK II Plus users who need to fax or email this data to INNOVENTIONS for analysis in regards to support issues.
Advanced users of the Simcheck II Plus can also use this feature to compare wiring architecture between two or more SDRAM devices, or for assistance in troubleshooting SDRAM devices with severe errors. This analysis is sent to your PC by using the Communications Diagnostics mode of the PC Communications software that was included with your tester. We recommend this information for advanced users only, as it requires knowledge of hex notation and structure analysis.
Setting Up SIMCHECK II Plus
In order for the SIMCHECK II to send the structure analysis of the SDRAM device to your computer, the "DEBUG3" flag must be switched on to enable the transmission of the structure information. To set this flag, make sure the unit is turned on and in standby mode, then enter the following key sequence:
Setting Up The Software
Activate the SIMCHECK II PC Communication Program, either from your desktop or through the Start - Program menu. Be sure to have your serial cable connected between the SIMCHECK's built-in serial port and one of your available COM ports on your PC. Select "Find SIMCHECK" from the SIMCHECK menu to make sure your computer detects your Simcheck II. Then click on the "OK" tab and select "Communications Diagnostic" from the SIMCHECK menu. The Diagnostic window will open, displaying the structure analysis. In case you do not have a clear screen simply click on the "Clear Input" tab to clear the screen.
Receiving the Structure Information
Insert the SDRAM device into the test socket that you want to analyze and press "F1" to start the Basic Test. You will immediately notice information being sent to your PC Screen, even if the Basic Test was aborted due to error detection. Once the information is received on your PC simply press the "ESC" key to end the Basic Test.
Saving the Structure Information
To save the structure information for future reference or to send it to INNOVENTIONS for further analysis, simply click on "Save As" in the file menu and save it as a text file using a name and directory of your choosing. If you have another SDRAM device you want to analyze simply click on the "Clear Input" tab to clear the Communications Diagnostic screen and repeat the instructions in the section above. If you plan to send us the structure analysis on your SDRAM devices you may print it out and fax it, or e-mail it to our Support Department (see contact information below). Note: Always include the test log of the SDRAM device as well.
Analyzing the Structure Information (advanced users only)
Below is an example of a screen dump of a working 2 bank 32Mx72 PC-100 SDRAM module.
The hexadecimal data in the 4 rows labeled , ,  and  is all that is required for the analysis. The rest of the data you see below these 4 rows you can simply ignore. Each row represents one of the 4 S lines and each hexadecimal number represents 4 data bits.
To better understand the mapping of these bits you need to transfer this information into a table specifically designed for this task. An example of this table from the Simcheck II Structure Analysis worksheet (click here to download PDF file) is shown below with the data from above already entered into it in blue. Note: For the rest of the examples in this document all data in blue is data retrieved from the Communications diagnostics screen on the PC.
The table above is divided into two sections, the "DQ BUS" and "CB BUS". Each bus is divided into two sub-sections, "DQMB 0123" and "DQMB 4567". The DQ bus represents data bits "63 - 0" and the CB bus represents CB bits (also called Parity) "15 - 0". Data bits with a value of '1' indicate activity at the specific Sx and DQMBxxxx setting. The bottom table is the sum of the two S lines per bank from the top table. S0 & S2 represent "Bank 1" and S1 & S3 represent 'Bank 2" of the module. Simply add the byte data per column between the S0 & S2 lines and enter the result in the row labeled "S0,S2(Bank 1)" in the bottom table. Do the same for the rows labeled S1 & S3 and enter the results in the row labeled "S1,S3(Bank 2)". For example, looking at the first column from the left on the top table above, S0=00 and S2=FF, you add FF + 00 which equals FF and enter it in the first column in the "S0,S2(Bank 1)" row of the bottom table. Do this across the whole table. Based on the data in the bottom table you can see that you have data bit activity on all 64 bits in the "DQ Bus" in both banks and bit activity on 8 bits in the "CB Bus" (parity) in both banks, which tells you that this module has two active banks with parity. Below is an example of a working 2 bank 16Mx64 SDRAM module.
Based on this data in the bottom table you can see that you have data bit activity on all 64 bits in the "DQ Bus" in both banks and no bit activity in the "CB Bus" (parity) in both banks, which tells you that this module has 2 active banks with no parity.
Note: Notice that the data bit activity is mapped differently in the top table in the "DQ Bus" compared to the first example. This shows that the wiring architecture of this module differs from the module in the first example. Below is another example of a working single bank:
Based on this data in the bottom table you can see that you have data bit activity on all 64 bits in the "DQ Bus" on only 1 row "S0,S2(Bank 1)" and no bit activity in the "CB Bus"(parity), which tells you that this module has 1 active bank with no parity. Together with information from the test log you can compare the wiring architecture between different brands of SDRAM modules.
Repairing Modules Using the Structural Analysis
Modules with severe problems, which report multiple or different errors each time they are tested during the Basic test phase of the Simcheck II Plus, can be further examined using the structure analysis to help determine the faulty bits or chip. Below is and example of a 16Mx64 SDRAM module which failed the Basic test with multiple data bit errors.
After transferring the sum of the 2 banks from the top table to the bottom table as explain earlier, notice that there is no activity on 2 bytes in "Bank 1" (highlighted in dark gray). Now look at the top table to see where these bytes are located in reference to the S and DQMB lines. In this case highlighted in the missing 2 bytes are both located on the "S2" line in sub section "DQMB 4567" of the 'DQ Bus" (highlighted in light gray). Using a functional block diagram of the module you are repairing you can look up what chips are connected to these lines to help you find the defective chip. Below is another example:
After transferring the sum of the 2 banks from the top table to the bottom table you can see that you have 4 bytes with missing bits (highlighted in dark gray), two of the bytes are in "Bank 1" and the other two bytes are in "Bank 2", unlike the previous example where the whole byte was missing. To determine the number of bits missing you will need to convert the hexadecimal to binary. In this case "F7" in binary is equal to 11110111 which shows 1 bit missing (highlighted in red). Since the other three bytes have the same value they also have 1 bit missing per byte as well. Next you will need to look at the top table to see where these bytes are located in reference to the S and DQMB lines. In this case highlighted in light gray, the missing bits are located on the "S2" and 'S3" lines across all 8 DQMB lines. Using a functional block diagram of the module you are repairing you can look up what chips are connected to these lines to help you find the defected chip. A continuity meter may also be used to help you trace between the chips and the 168p pin-out of the module. The list of the pin-outs for the S and DQMB lines is as follows.
This can be a very useful feature for advanced SIMCHECK II Plus users. Since the SIMCHECK II is not our current generation tester, no more firmware or hardware updates are planned for this model. All new testing and diagnosis features will be added to our current tester, the RAMCHECK. If you plan to repair SDRAM devices regularly we highly recommend converting or trading up your SIMCHECK II Plus to the RAMCHECK level, which has better capabilities for this task.
Contacting our Technical Support Department
For more information, please call us at 1(281) 879-6226 M-F 9:00-5:00 CST, or send your E-mail to email@example.com, or fax your message to (281) 879-6415. Please remember to include your phone and e-mail.
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