SPD Support Issues

1. Q. What is the SPD device used in modern memory modules?
   A. The SPD stands for Serial Presence Detect and it is a tiny serial EEPROM mounted on the memory module which contains various size, speed, structure and other manufacturing data. The memory manufacturer programs the SPD during the manufacturing process and there is no need for the memory user to change the SPD data. The computer's motherboard reads the SPD data during power up process and configures its access based on the SPD data.
   
   
2. Q. Can RAMCHECK support the SPD ?
   A. RAMCHECK has extensive support for SPD. During regular tests, RAMCHECK simply reads the data from SPD and compares it to the measured structure of the module. Advanced users and memory manufacturers can use RAMCHECK to program the SPD device as part of repair or manufacturing process. The PC Interface software allows you to edit, save, and send SPD data to RAMCHECK, 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 RAMCHECK'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 RAMCHECK's Production Mode for further information. You may also consult your manual for further details.
   
   
3. Q. What happens if the wrong data is programmed in the SPD memory?
   A. Since the motherboard uses the SPD data to configure the access to the memory module, the wrong SPD data can easily cause the system to crash. THEREFORE, ONLY ADVANCED USERS LIKE MEMORY MANUFACTURERS OR MEMORY REPAIR TECHNICIANS SHOULD ATTEMPT TO PROGRAM THE SPD DATA OF THE MEMORY MODULES.
   
   
4. Q. Can RAMCHECK inadvertently change the SPD data on a tested module?
   A. No. By default, RAMCHECK is setup to disable the SPD programming feature. Advanced users that want to enable SPD programming must activate various menus and go through several warning messages. Even when the SPD programming feature is activated, users needs to perform several steps (e.g. loading the SPD data from file) in order to program SPD. While RAMCHECK reads SPD data during normal tests, the SPD reading protocol is significantly different than the programming protocol. Advanced users who setup RAMCHECK to program SPD must put precautions in place to insure that only authorized personnel use the unit.
   
   
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. What is the new SPD Wizard and SPD Text Editors?
   A. The SPD Wizard is a specialized popup utility, which assist you in determining the functionality of each byte (and bit) of the open SPD file. With it, editing SPD files become much easier as you do not need to flip through several pages of SPD description manual - the SPD Wizard guides you on line!
   
   The SPD Text Editor provides a convenient and intuitive way for editing text sections of the SPD file. Further information is available from the on-line SPD Management section and your manual.
   
   
7. 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 RAMCHECK without pressing <ENTER> after the change will send the former information. We now recommend using the new SPD wizard for all SPD data change relating to memory parameters.
   
   
8. Q. The SPD on the 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-8668-APN13 and INN-8668-APN3 to review what the individual measurements mean.
   
   
9. Q. When programming the SPD, which locations should not be changed?
   A. The new SPD Wizard defines the function of each location of the SPD you try to change. We recommend that the SPD information be changed by the manufacturer only. Please refer to Application Note INN-8668-APN3 for an explanation of the SPD data.
   
   
10. Q. Can the RAMCHECK / RAMCHECK LX automatically determine and program the SPD data of a memory module?
    A. No. To the best of our knowledge, no test equipment in existence can automatically determine and program the SPD without engineering help - there are simply too many parameters, many of which depend upon information provided from the chip manufacturers or the board designer.

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