SDRAM SUPPORT & SDRAM Test Results

1. Q. Can SIMCHECK II support PC-133 modules?
   A. Yes. You will need to download the latest firmware revision and also to review Application Note INN-8558-APN18 that discusses PC-133 determination.
   
   
2. Q. What is SDRAM Technology? Can SIMCHECK II support SDRAM modules including the PC-100 or PC-66?
   A. Synchronous DRAM technology provides a revolutionary change in the way DRAM interfaces to a computer. It synchronizes all the read/write transfers to a system clock, thus providing significantly faster transfer rate for contiguous (same Row Address) group of data. A Synchronous DRAM can burst up to a full columns length of continuous data at the device clock rate (currently 100Mhz and higher rates). Both the SIMCHECK II and SIMCHECK II se RAM testers support our new Sync DIMMCHECK 168. This adapter readily supports PC-100 and PC-66 SDRAM memory. You may review Application Note INN-8558-APN14 for an explanation on how SIMCHECK determines PC-100 compliance.
   
   
3. Q. Does SIMCHECK II identify modules that support the Athlon processor?
   A. Yes, our current Sync DIMMCHECK 168 Adapter using ver. 1.49 identifies this module by displaying "SPD=CL2 at 100MHz" in the last summary screen as well as in the Test Log. For additional development information, please refer to our development log.
   
4. Q. Can I use the SIMCHECK II to program the SPD codes of my SDRAM memory?
   A. Yes. The PC Interface software allows you to edit, save, and send SPD data to SIMCHECK II, this data can then be used to program your modules. If you do not need to edit the SPD data, you may also elect to simply read the SPD information from a master module into SIMCHECK II's buffer and then use this data to program others, without using the PC Interface software. Please visit our page on SPD Management and our page on SIMCHECK's Production Mode for further information. You may also consult your manual for further details.
   
   
5. Q. Why can I program the SPD on some modules and not on others?
   A. The SPD chips employ a Write Protect Feature which may be active on your module. Typical SPD chips use pin 7 for this Write Protect line. This signal should be shorted to GND in order for the programming process to work. If this signal has been set to Vcc or left open, the chip will not be programmable.
   
   
6. Q. When using the SPD Hex Editor, why doesn't the information change when it is sent to the tester?
   A. After a change has been made in the Hex Editor, it is necessary to press <ENTER> afterwards, so the program will receive the changed value. Sending the SPD to SIMCHECK without pressing <ENTER> after the change will send the former information. Further information is available from the on-line SPD Management section and your manual.
   
   
7. Q. The SIMCHECK II memory checker shows the speed, Tac access time, and Page Burst. Which is the most accurate parameter for determining PC-100 compliance?
   A. There are various parameters that are needed to qualify a module for PC-100 compliance. Currently all of these figures are taken into consideration before SIMCHECK declares the module to be PC-100. You may review Application Note INN-8558-APN14 for an explanation on how SIMCHECK determines PC-100 compliance. Future firmware revisions may add some additional parameters to this determination.
   
   
8. Q. The SPD on the module tested says PC-66, but the test log shows that it is PC-100 Range, will the module work as a PC-100?
   A. All of the parameters measured indicate the module to run at a PC-100 level, and it may very well operate as PC-100, however, please remember that modules react differently under different loads. Some modules when used in a complete bank will slow down to the PC-66 level. Please review Application Notes INN-8558-APN13 and INN-8558-APN14 to review what the individual measurements mean.
   
   
9. Q. The SPD on the memory module says PC-100, but the test log reports it to be PC-66, is the module PC-100?
   A. Due to the possibility of loading, some modules may exhibit a slow down in speed. We recommend checking the Tac access times for further reference on PC-100 range. Also, refer to Application Notes INN-8558-APN13 and INN-8558-APN14 to review what the individual measurements mean.
   
   
10. Q. What Tac range is appropriate for PC-100 devices?
    A. Please refer to Application Note INN-8558-APN13 for an explanation of these limits.
    
    
11. Q. During the Extensive Test, the SDRAM module under test now runs at 83MHz. Does this mean that it is not PC-100?
    A. The only test that determines PC-100 compliance is the BASIC Test, so we ask that you check the results after BASIC Test. The frequencies used in the Extensive Test are for other tests altogether. Please refer to Application note INN-8558-APN14 for further information on PC-100 determination.
    
    
12. Q. When programming the SPD, which locations should not be changed.
    A. We recommend that the SPD information be changed by the manufacturer only. Please refer to Application Note INN-8558-APN12 for an explanation of the SPD data.
    
    
13. Q. Why do some SDRAM modules test faster than others even though they are the same size, and why does the PAGE BURST (red) LED flash on some modules and not on others?
    A. Some SDRAM modules employ a FULL PAGE BURST feature. SIMCHECK II takes advantage of this feature found in some SDRAM components and uses it to test the modules at a faster rate (shortening the overall test time). The Page Burst LED (red) will flash vigorously throughout the test if the module employs this feature. Please note, however, that a full page burst is not a requirement for PC100 or PC133 compliance. Also, those modules having such a feature will not have an advantage in systems over those not employing this Page Burst characteristic.
    
    
14. Q. The red LED is still on after the Basic Test. Is it safe to remove the module from the socket?
    A. It is safe to remove memory modules when the tester is in STANDBY MODE only. Some modules may exhibit a small current leakage that cause the red LED to remain lit after the test has completed, this is caused by a minute voltage that is present when the tester is in Standby Mode, however, you may safely remove the module when no test is occurring. We do, however, strongly recommend that the module under test remain in the socket while a test is in progress; you should NEVER remove it while it is testing!

If you have additional questions, please feel free to email us at support@innoventions.com. Please remember to include your phone and fax numbers.