on board memory - 600E - How to disable??

[octo]

I have a 600E with 32Meg RAM on the system board. On of the modules has a bad address (9F930). Byte 2 (the third from the right) is bad. Does anyone know how I can disable the on board memory? I have plenty of RAM left.

BTW, I found this with the Microsoft Memory Diagnostic. It works very well. The 600E memory diagnostic test found nothing. I used NERO to make a bootable CD using the Microsoft MTDIAG which creates a CD image.

[rkawakami]

Access the BIOS, select the Config button then press CTRL-D to access the hex editor. Byte 2B should be 80. Change it to 81 to disable the onboard memory. You can also download memtest86+ from here.

edit: Based on a similar request at TPF, I've put up a web site with pictures (!) on what's involved with making this change:

http://www.kawakami-ca.com/ibm_600x/disable_memory/

Message Edited by rkawakami on 05-22-2009 07:14 PM

[octo]

Ray, many thanks! You have saved my 600e. When  I changed the byte to '81'X, the system correctly reduced my memory from 288M to 256M, and programs are running just fine.

I notice that the Memory86+ you linked to, and the Microsoft Windiag at http://oca.microsoft.com/en/windiag.asp
appear to be identical. And both memory testers continue to find my bad address even though the BIOS has bypassed the low 32Meg.

[rkawakami]

I believe that if you happen to do a BIOS reset, the 2B byte will revert back to the default value and will re-enable your on-board memory. That would happen if you change the backup (CMOS) battery or select the option in BIOS to reset. I would have thought that either memory diagnostic would have "listened" to the BIOS and not tested the onboard bank of memory, but perhaps not. I've only done this hack once to check out a system problem (which wasn't anything to do with suspected bad memory) but I don't think that I ran any memory diagnostic to see what would happen.

[octo]

I checked the BIOS 2B byte - it was still '81'X. But these diags continue to find the bad address. It makes running the diagnostic futile - too many errors. I a;so tried reducing the memory to a single 128Meg stick in each of the socket locations --- same result.

But I am tickled with the recovery of my 600E! Thanks again, Ray.

[rodowen]

My 600x 2645 5FU freezes.   WMD (Windows Memory Diagnostics) consistently shows memory failure at 0009f930, regardless of how I set BIOS 2B.

WMD shows that setting BIOS 2B to 81x decrements total memory by 64MB, but that is high memory, not in the first 64MB.  The original memory reported for 64MB base memory plus two 256-MB chips is 589,248, in the following addresses:

00001000 - 00020000

00030000 - 0009fc00

00100000 - 00400000 

004de000 - 23fdf000

81x drops this down to 523, 712, ending at 1fdf000; 82x drops another 64MB, ending at 1bfdf000; and 83x drops another, ending at 17fdf000.  In other words, it looks like the DIMM RAM is being removed, not the onboard RAM.  (It's interesting that setting 2B to 81x on this machine drops memory 64MB, not the 32MB it does for the 600E.)

Lenovo System Toolbox memory test runs clean at whatever BIOS 2B byte setting.  (I will try that test at enough passes to see if it reports a failure eventually.) The machine runs normally, usually for an hour or more, and then freezes the cursor, keyboard, and display.  The CPU temperature remains fairly steady around 40C (per Notebook Hardware Control 2.0 Pre-Release-06).

Is it possible that the various non-Lenovo memory tests just look at memory starting at 00001000 regardless of the setting of address 2B?

Is there any documentation on the various settings possible at address 2B?  

Is there some setting that actually would bypass the onboard 64MB?  How could I confirm that?

Thank you very much. 

[tfflivemb2]

I believeI read somewhere that the BIOS mod only disables the Ram from being detected in the boot process and from OS usage, but using a Memory Diagnostic program will still detect it, because it is still attached...it just isn't being used.