i have a socket 7 motherboard gigabyte 5SMM
it has 3 dim slots. i have a bunch of different dims (like 50 of differet brand) and most of the 256 are detected as 128
only 2 stick of ram were detected as 256....bOth in reality were 512mb sticks pc133
is that normal or gigabyte had poor memory suport back in the day
Nope, problem is, that your motherboard takes low density ram, but your modules are high density.
Everithing works, but it only sees half of the memory.
I am aroused about any X86 motherboard that has full functional ISA slot. I think i have problem. Not really into that original (Turbo) XT,286,386 and CGA/EGA stuff. So just a DOS nut.
PS. If I upload RAR, it is a 16-bit DOS RAR Version 2.50.
The problem with terms like "low density" and "high density" are entirely relative so not very useful.
The GA-5SMM has a SiS 530 chipset. This chipset supports a maximum memory density of 128Mb (same as the i440BX). In 1998 this was 'high density' (as opposed to 64Mb chips), by 2000 this was 'low denisty' (as opposed to 256Mb chips) That means that the maximum supported chips are 16Mx8 and 8Mx16. I don't know if it supports 32Mx4 chips (i440BX certainly doesn't but Via ApolloPro133(A) does).
A single memory bank is 64b wide, so the highest supported bank size is 128Mbx8=128MB. With double-sided DIMMs (128b wide) you can do 128Mbx16=256MB.
If your 256MB DIMMs are detected as 128MB, that means that they have 256Mb chips, either single sided modules with 8 32Mx8 chips, or double sided with 8 16Mx16. The 512MB DIMMs are double-sided with 16 32Mx8 chips. As the SiS530 can only address 128Mb per chip, you get half capacity on all these.
So, for maximum RAM you need double-sided 256MB DIMMs with 16 chips with 16Mx8 structure, same as for i440BX. That way you can certainly get 512MB, and possibly 768MB (depending on max total number of banks supported, either 4 or 6).
wrote:The problem with terms like "low density" and "high density" are entirely relative so not very useful. […]
The problem with terms like "low density" and "high density" are entirely relative so not very useful.
The GA-5SMM has a SiS 530 chipset. This chipset supports a maximum memory density of 128Mb (same as the i440BX). In 1998 this was 'high density' (as opposed to 64Mb chips), by 2000 this was 'low denisty' (as opposed to 256Mb chips) That means that the maximum supported chips are 16Mx8 and 8Mx16. I don't know if it supports 32Mx4 chips (i440BX certainly doesn't but Via ApolloPro133(A) does).
A single memory bank is 64b wide, so the highest supported bank size is 128Mbx8=128MB. With double-sided DIMMs (128b wide) you can do 128Mbx16=256MB.
If your 256MB DIMMs are detected as 128MB, that means that they have 256Mb chips, either single sided modules with 8 32Mx8 chips, or double sided with 8 16Mx16. The 512MB DIMMs are double-sided with 16 32Mx8 chips. As the SiS530 can only address 128Mb per chip, you get half capacity on all these.
So, for maximum RAM you need double-sided 256MB DIMMs with 16 chips with 16Mx8 structure, same as for i440BX. That way you can certainly get 512MB, and possibly 768MB (depending on max total number of banks supported, either 4 or 6).
i think that is not always the case with this SIS 530, i think it has some kind of memory compatibility issue also
For example i tried 256 sticks that had memory on both sides, 16 chips total, and it also got detected as 128 only.
out of these for example, which ones would you choose? the ones that say 16CH on the sticker?
Socket 7 is really old back then intel did have only PCI set chipsets, later on on Slot 1 it was AGP set and did support a bit better memory.
So i think it will be from hard to impossible to use 256MB modules, in best case you will have no problems using 128MB modules. After all back in the days of S7 they did mostly use EDO 70 pin SIMM memory, not SDram so much, so total of 256MB memory for Pentium CPU, or even K6-II is overkill......
But if is possible, you need to look for some chipset, that is newer then intel PCI set, and you will need also some special SDram modules in order to run 512MB on S7 if you have only x2 SDram slots. Still i prefer using EDO SIMM then SDram, as the SDram on S7 is cheating...
Mah systems retro, old, newer (Radical stuff)
W3680 4.5/ GA-x58 UD7/ R9 280x
K7 2.6/ NF7-S/ HD3850
IBM x2 P3 933/ GA-6VXD7/ Voodoo V 5.5K
Cmq P2 450/ GA-BX2000/ V2 SLI
IBM PC365
Cmq DeskPRO 486/33
IBM PS/2 Model 56
SPS IntelleXT 8088
I have GA-5SMM and some 256MB sticks that can be fully recognized by the board. If I were given a new bunch of 256MB sticks, I would look up the datasheets of the chips on the memory sticks and try the sticks with 16M x 8bit chips. 256MB sticks with 32M x 4bit chips may also have 16 chips and appear double-sided but the board can only recognize half of the capacity. I guess the board can only address up to 16M per chip. 256MB sticks with 8 chips often use 32M x 8bit chips and again only 16M per chip is recognizable.
