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shanchya
Joined: 10 Jul 2007
Posts: 40
Location: Bahgladesh
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 Posted: Mon Sep 23, 2019 11:58 pm Post subject: Info request regarding a SIMM RAM |
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| Guys, can you please help me to identify this RAM ? |
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CPUShack
Joined: 16 Jun 2003
Posts: 34259
Location: State of Jefferson, USA
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shanchya
Joined: 10 Jul 2007
Posts: 40
Location: Bahgladesh
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| Posted: Tue Sep 24, 2019 2:30 am Post subject: |
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| CPUShack wrote: | | IBM 30-pin 512K with parity |
Many thanks ... but is there any way to read them ? coz i have about 400 RAMs, and now i need to make a catalog. it is very difficult to search on internet with all the part number / IC number / Model # (sometimes they do no have any  .... ) .... So could you please share some documents (if there is any) for 30 and 72 pins SIMM RAM, like how to read the capacity ?
Thanks a lot again ... by the way the RAM in the picture, is my second RAM that i collected. first one was 1MB IBM's 30 pin SIMM RAM (brown PCB) ... |
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H3nrik V!
Joined: 15 Apr 2014
Posts: 1246
Location: Denmark
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| Posted: Tue Sep 24, 2019 2:50 am Post subject: |
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If that RAM works, it is awsome for a vintage computer!  |
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cuttingedgecs
Joined: 08 Oct 2017
Posts: 1764
Location: Australia
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| Posted: Tue Sep 24, 2019 3:09 am Post subject: |
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| There's no 100% way to be sure without looking up the part numbers, but with older/smaller RAM, the part number sometimes makes the capacity obvious. So for example if you have a 30 pin simm with 3 chips, and two of the chips have a part number that contains 4256, and the other chip has a part number with 1256 in it, you can fairly safely assume this is a 256KB module without looking up the chips. Here the 256 is the kbits, and the 4+4+1 is the bus width = 8 bits plus parity, for a total of 256KB. Many chips will have this pattern or something like it. |
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cuttingedgecs
Joined: 08 Oct 2017
Posts: 1764
Location: Australia
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| Posted: Tue Sep 24, 2019 3:14 am Post subject: |
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| The other quick way that often works is to look at the spec of the 30/72 pin edge connector and see what address lines are connected on the simm you want to check. If an address line isn't connected to anything, then there can't be addressable memory there, so you know the capacity is less than that. |
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shanchya
Joined: 10 Jul 2007
Posts: 40
Location: Bahgladesh
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| Posted: Tue Sep 24, 2019 3:17 am Post subject: |
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| thanks a lot @cuttingedgecs ... i will try to do as you said |
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