Please help me identify what kind of RAM is in these photos?

[microfloppydik]

Ok,

First post here, so please be gentle.

Also, I'm not sure if I posted this in the wrong forum or not - moderator, please help.

I'm trying to figure out what kind of RAM or modules are in these photos because I have no idea.
Can you help?

There are three rows. I also took pictures of the backsides in the second photo.

Thank you very much in advance.

 

[per]

Chip with 4 sets of 5 legs: 1Mx1 bit. May also be 256Kx4 bit or even 256Kx1 bit on older 30-pin SIMM modules.
Chip with 4 sets of 6 legs: 1Mx4 bit.
Chip with 4 sets of 7 legs: 4Mx4 bit, only used on later 72-pin SIMMs.

Just add the bits from all the chips together, and divide by 8 bits per byte for non-parity or 9 bits per byte for parity. For the speed rating, the chip ID often ends with something like "-70" or "-80", indicating access time in nanoseconds. For Fast-Page vs EDO, you can typically make a good guess from the chip ID again. The capacity part of the ID usually ends with zero for Fast-Page, but might often (but not guaranteed always) end on a non-zero digit for EDO. How to read the chip ID varies a bit from company to company, but is generally about the same for most of them. Usually something along the lines of:

[Manufacturer identification letters][DRAM product identification number][Maybe a letter for technology used][Capacity number][Packaging identification]-[Speed rating]

Example: KM44C1000BJ-6

Manufacturer ID: KM (Samsung)
Product code: 44 (x4 bit DRAM)
Technology: C (CMOS)
Capacity: 1000 (1M, Fast-Page. There is no EDO, and I can say this with absolute certainty since the datasheet for this chip is available online.)
Package: BJ (300 mill, 20-pin SOJ)
Speed: 6 (60ns)

Hope this helps!

 

[jmetal88]

As for what kind of modules, it looks like you have some 30-pin SIMMs, some 72-pin SIMMs, and some 168-pin DIMMs.

 

[ropersonline]

Were there even 286-class PC-compatible boards with these kinds of SIMMs?
(Since this subforum is technically for "Older PC architectures from IBM and others - 8088 to 286 only". No worries though.)
I'm just saying, because my 286 had DRAMs. My guess would be that these SIMMs might be 386/486-generation, maybe early Pentium, but I'm not sure.

 

[per]

Were there even 286-class PC-compatible boards with these kinds of SIMMs?
(Since this subforum is technically for "Older PC architectures from IBM and others - 8088 to 286 only". No worries though.)
I'm just saying, because my 286 had DRAMs. My guess would be that these SIMMs might be 386/486-generation, maybe early Pentium, but I'm not sure.

30-pin SIMMs came around just around the time the 386 became popular, so some of the last 286 machines quickly adapted to using them as well. The IBM XT/286 is one example of a 286 machine with SIMMs (allthough only for 512KB fixed in conventional RAM space).

A problem with the use of SIMMs in 286 machines is that the 286 lacks the dynamic memory mapping features introduced with the 386. This limits what you can do with additional RAM on the motherboard unless the board designers put in some extra memory mannagment hardware. With the 386 all of the memory mannaging is in software so the onboard RAM just becomes a pool of memory you can use however you want.

 

[lowen]

Were there even 286-class PC-compatible boards with these kinds of SIMMs?
(Since this subforum is technically for "Older PC architectures from IBM and others - 8088 to 286 only". No worries though.)
I'm just saying, because my 286 had DRAMs. My guess would be that these SIMMs might be 386/486-generation, maybe early Pentium, but I'm not sure.

This subforum's scope includes PS/2 Models 25 and 30, and they used 30-pin SIMMs (they were, if I remember correctly, the first users of SIMMs, but I reserve the right to be wrong).

While I don't know of a non-PS/2 8088-class machine using SIMMs (or SIPP's for that matter) it doesn't mean that none are around. Likewise for 286 machines.

 

[Stone]

My 286 uses only SIMMs:

http://stason.org/TULARC/pc/motherboards/W/WESTERN-DIGITAL-CORPORATION-286-WD286-WDM20.html

 

[Krille]

This subforum's scope includes PS/2 Models 25 and 30, and they used 30-pin SIMMs (they were, if I remember correctly, the first users of SIMMs, but I reserve the right to be wrong).

While I don't know of a non-PS/2 8088-class machine using SIMMs (or SIPP's for that matter) it doesn't mean that none are around. Likewise for 286 machines.

According to Wikipedia, Wang Laboratories invented the SIMM. And my Wang PC 250/16 uses SIMMs only.

 

[krebizfan]

Many memory expansion cards that supported EMS 4.0 used SIMMs. So an XT or AT equivalent system could well need 30-pin SIMMs even if the motherboard had only socketed chips.
Don't forget that 30-pin SIMM sockets were also common with higher end sound cards and caching disk controllers.

 

[microfloppydik]

Thanks for replies everyone - it was much more detailed than I expected.

Anyone have an idea of how much they all might be worth if I were to sell them?
Thanks again.

 

[Wildman]

there's two modules in the middle row on the left that aren't any kind of memory I have ever seen, looks more like some kind of apple ROM sticks or something.

 

[Anonymous Coward]

I think I saw a 64-pin SIMM in there as well.

 

[GiGaBiTe]

there's two modules in the middle row on the left that aren't any kind of memory I have ever seen, looks more like some kind of apple ROM sticks or something.

They look like Power Macintosh cache modules. I have a 6360 and 6400 that have cache modules that look like that.

It'd be interesting to know what size they were.