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30 pin memory simms

Posted on 1999-01-04
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I thought I had already asked this.... But obviously not because I do not see it here.
I HAVE COME INTO A OLDER COMPUTER. IT SAYS 386 ON THE CASE BUT IT CLEARLY HAS A 486DLC CPU INSIDE IT.
IT ALSO CONTAINS 8 - 30 PIN MEMORY MODULES - WHICH AT BOOT UP AND IN WINDOWS TELL ME THE TOTAL IS 5MB. (YES 5 mb)
I HAVE READ THAT SOME 30 PIN MODULES ARE FOR 386'S AND OTHERS ARE FOR 486'S.... I AM VERY CONFUSED AS TO WHAT I NEED AND WHERE TO GET THEM. I WOULD LIKE TO RAISE THE MEMORY TO AT LEAST 16MB SO THAT I CAN RUN APPS AT A NORMAL PACE.
IF THERE IS ANY EXPERT OUT THERE THAT REALLY UNDERSTANDS THESE OLDER MEMORY CHIPS AND SET-UPS, PLEASE GIVE ME SOME ADVICE. I WOULD LIKE TO KNOW WHAT I CAN OR CAN NOT USE. AND HOW I CAN ACHEIVE THE 16MB FIGURE I WANT. WHY ARE THE'RE 8 SLOTS IN THE FIRST PLACE??? SEEMS STRANGE. HOW CAN MY FULL 8 SLOTS COME TO 5MB'S??? THANKS FOR ANY HELP.
If you do not know for sure that your answer is 100% of which I seek - Do not lock the question. I will award the points to the person with the best and most detail answer. I prefer comments instead of locked answers so I have more than one opinion to evaluate. I WILL AWARD THE POINTS AS PROMISED TO THE BEST ANSWSER!!!
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Question by:chinman
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by:heathprovost
ID: 1132430
I will address your points one at a time

>>"I HAVE COME INTO A OLDER COMPUTER. IT SAYS 386 ON THE CASE BUT IT CLEARLY HAS A 486DLC CPU INSIDE IT."

This is quite common.  The reason is that many chips built by AMD (and IBM for that matter) at that time were labeled as 486 but were actually souped up 386s (they used the 386 interface and pinout and required 386 MBs).  If I remember correctly the 486DLC was one of them, at least the earlier versions were.

>>"IT ALSO CONTAINS 8 - 30 PIN MEMORY MODULES - WHICH AT BOOT UP AND IN WINDOWS TELL ME THE TOTAL IS 5MB. (YES 5 mb)"

If it has 8 slots then it will require memory to be installed in quads (4 simms per bank, 2 banks).  As for how there can be 5MB, your board will currently have 4 1MB simms in one of the banks, and 4 256K simms in the other.
>>"I HAVE READ THAT SOME 30 PIN MODULES ARE FOR 386'S AND OTHERS ARE FOR 486'S.... I AM VERY CONFUSED AS TO WHAT I NEED AND WHERE TO GET THEM. I WOULD LIKE TO RAISE THE MEMORY TO AT LEAST 16MB SO THAT I CAN RUN APPS AT A NORMAL PACE."

In a word no.  There are basically 2 catagories of 30-pin memory.  It is either parity or non-parity.  Which is required is determined by the MB, but most at that thime period used parity.  Many could use either/or, but not at the same time.  I would try parity memory first, but that is mostly an educated guess.

>>"HOW I CAN ACHEIVE THE 16MB FIGURE I WANT."

What I would do is purchase either 8 2MB parity simms or 4 4MB parity simms.  If you purchase the 4 4MB, there is a chance your MB wont work with simms larger than 2MB (a good chance, not many did). If 8 2MB parity simms dont work, then 8 2MB non-parity simms should.  There are many other things to consider (like 3 chip vs 9 chip simms) but I dont think anyone could give you concrete answers without knowing exactly what kind of MB this is.

Hope this helps
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by:j_powers
ID: 1132431
It is not a question of 386 memory, or 486 memory, it is a question of speed.

This is how 30 pin memory works. 1 simm cannot handle the whole motherboard (call it faulty achetechture, or sellability, etc). For a 486, 4 simm slots have to be filled with working simms to have the machine recognize the memory (there is always an exception, but for the most part, this is the case).

There are MANY DIFFERENT VERSIONS OF MEMORY. Let's start with 1 meg 100n(n=nano-second) memory. They usually have gold colored connectors. Then there is 70n and 60n memory. They run faster, and are silver plated. Finally, with 30 pin simms, you can have a 128k simm, a 256k simm, a 512k simm, a 1M (1024k) simm, a 2M (2048k)simm, and a 4M (4096k) simm.

Here is where it gets tricky. IBM made a different type of 30 pin memory, because they made a MCA type machine (MCA= Micro channel archetechture, IBM, and Memorex - Telex made these machines, MCA did not survive, due to selective marketing). Compaq, on the otherhand did not make a MCA machine, but they had what is called "proprietary memory", which meant that you could not use their memory in other machines.

Now you said that you have 8 simms read 5 megs. These simms may not be 1 meg simms. In fact, from what I just said here, you PROBOBLY HAVE 4 - 1 meg simms, and 4 - 256k simms, Totaling 5MEGs.

Try this: take out 4 of the simms, and turn on the computer. Note what it counts to. Remove those simms (NOTE: BE CAREFULL with 30 pin simms. Ground yourself by touching metal, and do not move around too much when handling simms. Static electricity can ruin a 30 pin simm), then put the other 4 in. Note what that counts to. If 4 of the simms counts up to 1 meg, then these are 256k simms.

Let me know what happens.
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by:kayton
ID: 1132432
Rather than spending money buying 4 MB 30-pin SIMMs, it is cheaper to buy a new Pentium motherboard with 72-pin memory and a slow Pentium (say 166 MHz).  It will run faster, too!
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by:istal112898
ID: 1132433
To start, it is expensive to upgrade what you are asking to. the motherboard has 8 slots.
now if you want to use 16 megs. you will need to buy 4  4 meg chip 30 pin, also speed problem, we can not know if it is 90 or 80 NS, mostly the mem sold today is 70 to 60ns for 30 pins. if we do the math. new chip for 4 meg cost about 13$ a piece in USA.
that means that you need to invest at least 52$ plus shipping. maybe 60$.
now, a motherboard that uses 72pins and in some cases 168pin. can cost you as low as 29$ bucks.MB 559 VXProII 4 PCI 2
        ISA 4 SIMM 2 DIMM
        50~75 BUS, 75to233
        CPU ON BOARD
        SOUND
888-225-4277 http://www.buypcparts.com

now some old motherboard requires you to use the 8 slots. so that would be over 100$ cost. if you, upgrade, for almost the same amount of money you get better performance and a new system.
check www.pricewatch.com for prices. even combos for CPU with MEM, and Motherboard.
you will be better upgrading.
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vidrine earned 50 total points
ID: 1132434
It appears that you have 1 Meg Onboard memory (Cannot be removed) with (8) 256k simms.  The older MBs seem to allow specific memory upgrades arbitrarily.  Without the original guide, it would be trial and error.  Odds are, however, you could fill a bank of 4 4MB simms to get a total of 17MB ram.  If trying this in one bank fails, be sure to try the other bank.
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by:vidrine
ID: 1132435
Oops ... I meant # megs onboard, so you should get 19 megs by putting in 4x4MB
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by:istal112898
ID: 1132436
Other OPPS, you should not have locked the question yet. you should have read his question completely VIDRINE.
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by:ili121098
ID: 1132437
The difference between 386 SIMMs and 486 SIMMs is between 386sx and 486/386 (other than sx).
The 386sx works, like a 286, with a 16bit databus.
Better than 386sx (386 - Pentium) CPU`s, are working with 32bit databus and need the double amount of RAMs.
 - The construction is the same!

Perhaps you have 1MB fixed on board. Than to get 5MB you have installed 4 x 1MB modules or 8 x 512kB modules.
You wouldn`t get 16MB, but 17MB with 4 x 4MB modules (4 x 4 + 1).
Otherwise your banks (4 modules = 1 Bank) are filled with 4 x 1MB and 4 x 256kB. To get 16MB install 4 x 4MB and 4 x 256kB (4 x 4 + 4 x 0,25).

And the insanity with the RAMs goes on...
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by:j_powers
ID: 1132438
we need some input from you chinman. If you do not respond, then EE will award the points to vidrine by default.


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