ThinkPad 770 X/Z Memory matrice ?

[DK6400Brian]

Hi folks.

In order to clear things out and perhaps be able to install 768 MB RAM in the ThinkPads 770X and 770Z, I need some help to determine the memory matrice in these machines.
The is a slight chance, that a bit in a byte in the CMOS map perhaps could alter this limitation.

There's three slots, DIMM-0, DIMM-1 and DIMM-2 available.
DIMM-0 is reachable if the machine is disassembled.
DIMM-1 and -2 is the user upgradable slots.

DIMM-0 has two banks, 0 and 3
DIMM-1, has bank 1 and 4
DIMM-2, has bank 2 and 5.

Each bank can take 128 MB.
A 128 MB stick is a one-bank mamorystick.
A 256 MB 16-chip is a two-bank memorystick.

In DIMM-0 sits a 64 MB stick from the factory.
It uses one half of either bank 0 or 3.
It can be replaced with at least a 128 MB stick.

It's well known, that these machines can take 2 sticks of 256 MB RAM, giving a total of 512 MB usable RAM, but what truly happens ?

Using 256 MB in either DIMM-1 or DIMM-2 swaps out all the memory in DIMM-0.
I have 512 MB in mine, but using SiSoft's Sandra, it told me, that DIMM-0 was free, even though that there still were a 64 MB stick in it.

Which of the DIMM-1/-2 is it, that swaps out the access to DIMM-0 ?

What works, what doesn't ?

DIMM-0, DIMM-1, DIMM-2

64 MB 64 MB 64 MB = OK
64 MB 64 MB 128 MB = OK
64 MB 128 MB 128 MB = OK
64 MB 128 MB 256 MB = ?/OK
64 MB 256 MB 128 MB = ?/OK

128 MB 128 MB 256 MB = ?/OK
128 MB 256 MB 128 MB = ?/OK

256 MB 128 MB 128 MB = ?
256 MB 256 MB 128 MB = ?
256 MB 128 MB 256 MB = ?
256 MB 256 MB 256 MB = Not OK.

256 MB 0 MB 0 MB = ?
256 MB 128 MB 0 MB = ?

0 MB 256 MB 256 MB = OK.

It's important to clear out what the machine does, in order to narrow down the possibility of the one bit in CMOS, that points to the specific bank/banks and probably just needs another value.

In reverse it seems to be the case, that the CMOS in the very similar machine, 600E, has a bit in a byte, that can be changed, so the soldered onboard base-memory (66 MHz) in 600E can be ignored, in order to avoid trouble, when upgrading the 600E to 100 MHz FSB/P-III.

I hope I make myself understandable

Which combination of RAM worked for you in the 770X/Z ?
Which didn't ?
What happens when using a 256 MB stick in the basememory alone ?

Kindest regards
Brian

[JHEM]

Brian,

I've put 256MB PC100 sticks in the 0 memory slot of the 770Z in an attempt to break the 512MB memory limit, but it didn't work. I've only been able to get a stable machine with 128MB sticks in slot 0 and slot 1 and a 256MB stick in slot 2 for 512MB total.

128MB in slot 0 and 256MB sticks in slot 1 and slot 2 still results in 512MB RAM, as does leaving the standard 64MB in slot 0 and adding 256MB sticks to slots 1 and 2, or removing the memory completely from slot 0 and adding 256MB sticks to slots 1 and 2.

In the past I have been told that slots 0 and 1 are shared and this is the reason that the slot 0 memory is mapped out when 256MB sticks are installed in slots 1 and 2.

Regards,

James

[DK6400Brian]

Thank you James.

My own working max-combination were until now:

DIMM-0 : 64 MB [Ignored]
DIMM-1 : 256 MB
DIMM-2 : 256 MB

Exchanging the P-II366 with the P-III850 gave me the opportunity to take out the 64 MB, so now it's:

DIMM-0 : 0 MB
DIMM-1 : 256 MB
DIMM-2 : 256 MB

It took me three hours to follow the HMM for the first time in 1½ year, so in the first place, it'll be fine if the used combinations among ThinkPad-users can be recalled from the hidden depths of the past.

Otherwise I'm forced to have my machine taken apart for research.
Perhaps I'll just do that.
I have the appropriate sticks laying around, 64/128 and 256 MB.

With these, a handful or two of reboots and SiSoft Sandra, the true use of banks/DIMMs can be recovered.
That'll have to wait until next week or at least until tonight

Thanks again James.

Kindest regards as usual
Brian

[DK6400Brian]

Okay....

I've been told by Sharedoc, that byte 2B in CMOS Base 128 controls the SDRAM banks..

I quote:
"in 600E byte 2B of CMOS controls the SDRAM banks. Bit b0 disables internal 32M memory. By changing the content from 80 -> 81 the 32M is disabled.

Bits b1 ... b7 control other memory banks.

Here is my trial log (I don't remember how much memory I had installed, propably 32 + 128 + 128)

Initial value 80
81 (disables internal 32M)
82 and 83 ?130M
84 228!
88
90 294
A0 228M!
C0
7F no post"

Now, two jobs

One: I would like everyone who read this, to tell what she or he see in CMOS, byte 2B.

Hold F1 down at cold boot, until EZ-setup appears.
Go into "Config" - hit CTRL-D

Look at the position marked with this **.
0 1 2 3 4 5 6 7 8 9 0 A B C D E F
00
10
20...............................**
30
40
50
60
70


What does it say ? 80 ?
In order to get out, hit ESC, EXIT and Restart.

Report also how much RAM you have installed, and in which DIMMs/slots they sit.
Ex. DIMM-0: 64 MB, DIMM-1: 128 MB, DIMM-2: 128 MB

This applies to the 600, 600E, 770X, 770Z
Report also which machine you have.

Job two:
I will try to avoid burning my hands, when I take my machine apart tonight and fiddle with different combinations of RAM and different settings in CMOS.
There just *have* to be a way
Anyone knows this feeling ?

I hope someone will report back.
Every piece of information is welcomed with a blessing and kind thoughts.

Thank you

Brian

[DK6400Brian]

Okay.
Here's the result.

ThinkPad 770, P-233MMX, TX-chipset.
Onboard-DIMM-0: 32 MB, Bank-0
DIMM-1: 128 MB, Bank 1-3
DIMM-2: 128 MB, Bank 0-2

Installed RAM: 294.912 KB
Maximum usable RAM: 228.800 KB

The 64 MB in DIMM-2/Bank-0 were ignored.
Bank-0 in DIMM-0 had highest priority.

Bit b0=1 disables Bank-0, but don't liberate Bank-0 in DIMM-2.
Result: 196.032 KB

Bit b1, b2, b3 =1 disables something on Bank 1,2,3 and leads to error.
Result: 163.264 KB

Bit b0+b1 or b2 or b3 disables 2 Banks in a row.
Result: app. 130.000 KB

Bit b4+b5+b6+b7 = 0 or 1 have no effect.

Byte 2B, initial value: 80, RAM 228.800 KB

81: 196.032 KB. Onboard RAM ignored.

82: 163.264 KB, Sandra couldn't launch. Error.

83: 130.000 KB.

84: 163.264 KB, Sandra couldn't launch. Error.

85: 130.000 KB.

88: 163.264 KB, Sandra couldn't launch. Error.

89: 130.000 KB.

90: 228.800 KB.

A0: 228.800 KB.

C0: 228.800 KB.

Odd combinations:

91: 196.032 KB. Onboard RAM ignored.

A1: 196.032 KB. Onboard RAM ignored.

C1: 196.032 KB. Onboard RAM ignored.

F1: 196.032 KB. Onboard RAM ignored.

F0: 228.800 KB

8F: ERROR. No boot.
I guess all banks are ignored, and not even BIOS can copy itself in order to boot.

8E: Didn't try, but I guess it'll show about 32.000 KB, since only Bank-0 is open.

Hmm...too bad. No luck in Byte 2B

I did try with my daugthers ThinkPad 600 with P-II 300 MHz, 440BX-chipset.
Same thing goes. No luck.
Same results.

Now......I'm dead tired and I'm off for tonight

Tomorrow is another day

[Crossposted in Wim's BIOS forum]
_________________________________
Post Scriptum:

Please notice, that SiSoft Sandra reports 4 banks in an old Thinkpad 770.

DIMM-0, bank 0
DIMM-1, bank 1-3
DIMM-2, bank 0-2

In an 770, the bank are shared.

But....in the 770Z....*all* DIMMs have seperate/individual banks.
DIMM-0, bank 0-3
DIMM-1, bank 1-4
DIMM-2, bank 2-5

Now...something just *gotta* determine, swapping out the DIMM-0 in the Thinkpad 770X/Z.....grrrrr.

Goodnight. See 'ya all later.
_________________________________

Kindest regards
Brian