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RAMCHECK Application Note

Permanent Software Write Protect Feature (PSWP)

--Created 11-16-06

(Note: This feature requires RAMCHECK firmware version 2.30 or higher.)

SPD EEPROMs are found on modern memory modules. Many newer modules incorporate a permanent software write protection (PSWP) feature that write protects the first-half of the SPD EEPROM chip (Byte 0-127) by sending a special command to the SPD chip. Once set, the SPD can be changed only by physical removal and replacement of the SPD chip. You can still write to the second half of the SPD EEPROM without any difficulty, but this section of the SPD is not considered by the motherboard controller. The PSPW feature is useful to keep the integrity of the module data parameters that are recorded in the SPD by the manufacturer from being changed by a third party.

In an effort to support RAMCHECK users who are interested in this feature, INNOVENTIONS has recently enhanced our RAMCHECK SPD Management program to allow advanced users to work with the PSPW feature. However, serious care is required since this feature is irreversible and using the wrong spd data will cause the memory module to malfunction in most applications.

We have protected this feature with a special activation code that prohibits casual users from inadvertently setting the PSPW. To use the PSPW feature on RAMCHECK you must sign a release form that states that you understand the risk involved and that you use it on your own risk. If you are interested in this PSWP feature please contact us (see below) so we can send you the release form and the activation code.

Once you obtain the activation code please follow these instructions:

In order for the PSWP feature to be functional you must first enable "Programming Mode". To do so while the RAMCHECK is in standby mode press F2 for Setup, then F5 for NEXT, then F2 for SPD. A warning message will appear. Once the warning message disappears press F2 for "PROGRAMMING MODE", next press F5/F2 to select your choice (for example, "BYTE MODE PROGRAMMING"), then press F1. Press the ESC key 4 times and you should see "SAVING to EEPROM". Now the Programming mode is enabled even if you turn the RAMCHECK off. The only way to disable it is to follow the steps above and select "DISABLE".

Now that the "Programming Mode" is enabled you can now use the PSWP feature. The PSWP feature is located in the SPD Management section. While the RAMCHECK is in standby mode press F4, then F3 for "SPD Management", then F5 for MORE. You have two options for the PSWP feature, F2="Check PSWP" and F3="SET PSWP".

"Check PSWP" is a feature that does not require the code. It simply determines if the SPD chip of the module you have inserted supports the PSWP feature or if the PSWP has already been set or is not supported. For example if the SPD chip supports the PSWP, pressing F2 will give you this message:

"Permanent Software Protection of the SPD is not Set"

If the SPD chip already has the PSWP set or is not supported, pressing F2 will give you the following message:

"Permanent Software Protection of the SPD is on ! ! (or PSWP is not supported)"

"SET PSWP" does require the code since this is the function that actually sends the WP command and once done is irreversible. When you Press F3 for "SET PSWP" for the first time you will get a quick message stating that "the access code is available through our tech support." Once this message disappears a screen will come up to enter the code. Please contact INNOVENTIONS for the activation code.

Once the code is entered you do not need to enter it again unless you turn off the RAMCHECK. A menu will appear with two choices, pressing F1 will continue with the Write Protect command, if it goes through it will display "Success", if not it will display "Failed". The other choice is the ESC key to abort.

It is recommended that you use the "Check PSWP" command first to make sure that the SPD chip you are trying to PSWP supports it. As long as you get "Permanent Software Protection of the SPD is not Set" then the "SET PSWP" should work fine. If you want to disable the PSPW feature so someone can not accidentally Permanently Write Protect a module being tested, simply turn the RAMCHECK off then on again. This will disable the SET PSWP and you will need to enter the code again to re-enabled it.


For more information, please call us at (281) 879-6226 M-F 9:00-5:00 Central Time, or send your e-mail to support@innoventions.com, or fax your message to (281) 879-6415. Please remember to include your phone and e-mail.

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