upgrade to 486 (edo ram)

[grant99]

please help..i'm a newie!

i have a 486 with 16mb(edo ram)
i had hoped to upgrade the ram to 32 or 64mb.

i bought 4*16mb(72 pin simm)edo ram only to find3/72 pin simms
on the cpu?
i then took the original 3 simms out(1*8mb and 2*4mb)
when i replaced these with 2*16mb i switched the computer
back on to find that my monitor would not switch on and
the computer would not boot up.
(i had been informed that the monitor would work and see the
ram increase to a wonerful upgrade of at least 32mb!)
after reading some of the pages in this guide i believe
that maybe someone with computer knowledge(and patience!)
could help me resolve this problem.
i would be very grateful for any help that you could provide
me with.

many thanks.

[ReddDogg]

Just a quick question, did you try putting the 16's in where the 4's were before, and leaving the 8 in there??? or even try all three slots with 16's??? Just curious.

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Joe Redd
MCP

[Reid]

Can you find a model number on the motherboard. Something sounds unusual to me. I can't find any 486 motherboard with three 72 pin SIMMs. Some have two 30 pin and one 72 pin, but an odd number seems to be just that, odd.

------------------
rdrummond@thesimpsons.com

[Paleo Pete]

I've never heard of a board with only 3 slots... This one only has 3???

Try the chips one at a time, only long enough to see if you get video, then shut down. One chip may be bad. Check the board, one slot should be marked bank 0 or bank 1. That's the first slot to use.

72 pin SIMM must be installed in pairs, which is why I was wondering about 3 slots...but you can try them one at a time, just long enough to see a picture.

Make sure you don't have the memory plugged in backwards. It's not easy, but can be done..

A 486 is an older machine, the memory, if newer, could easily be the wrong density and therefore incompatible, or could be the wrong access speed. If it's too fast, it might not work. That's the 6ns or 7ns speed, which should be the last number stamped on the chips.

Where did this new memory come from? Reputable source or online auction, mail order, etc? Could be you got Fast Page Mode or non-parity instead of EDO. And are you sure EDO is what your machine uses?

Also, memory is highly susceptible to ESD, or static electricity. If you handled it without being grounded first, it is possible it was fried the instant you touched it. When you touch a doorknob and get a shock, that's at least 2000 volts minimum. Computer components can be toasted by less than 100 volts, especially memory.

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Soon as I come up with all the answers...they change the questions!!

Computer Information Links (http://www.geocities.com/paleopete/)

[grant99]

thanks for the replies!

i'll try to amswer all the questions.

there is definately only 3 simm slots.
the ram i recieved ....i bought from the add mag but is definately edo.
the mother board is a "schematic:486-gac-2-04-05"i think
definately no 30 simm slots
there is one curious thing though.....the simmswhen in place)dont stand upright?they are at an angle of about 20 - 30 degrees?
i don't know why this is but just above the simm slots(which are toward the front of the unit)there is another board which has "vibra A(without the -in the letter A)16?this i believe is stopping the simms from standing upwards and may be why the design is for the slots to be at an angle?
i've just looked at the ram and on the back of 2 of them are the letters"sd7228....94v0"the others have no markings at all!
once agian thanks for the quick replies,i hope that you can shed some light onto this for me.
i'm going to try some of your suggestions and i'll be back in a while.

many thanks!

[grant99]

thanks for the replies.
i've tried all mentioned and have found that there are 3 simm slots named"banks1+2"same slot,"bank 1"and "bank 4"
the slots will register memory as follows.....banks1+1 will register upto7020meg(just under 8),banks 1 and banks 4 will each hold 3020meg ram.
does this mean that all i can hope for is 16meg max?
the board make and model is a "schematic:486-gac-2-04-05"and the compuet specs are as follows......486dx2 50mhz(i know not much!)base memory 640
with extended mem upto 16 meg at the moment.
would it be in my best interests to upgrade the mother board?

i have a 486 with 16mb(edo ram)
i had hoped to upgrade the ram to 32 or 64mb.

i bought 4*16mb(72 pin simm)edo ram only to find3/72 pin simms
on the cpu?
i then took the original 3 simms out(1*8mb and 2*4mb)
when i replaced these with 2*16mb i switched the computer
back on to find that my monitor would not switch on and
the computer would not boot up.
(i had been informed that the monitor would work and see the
ram increase to a wonerful upgrade of at least 32mb!)
after reading some of the pages in this guide i believe
that maybe someone with computer knowledge(and patience!)
could help me resolve this problem.
i would be very grateful for any help that you could provide
me with.

many thanks.[/QUOTE]

[grant99]

its a schematic:486-gac-2-04-05?banks2=3 are i in the same simm slot(same simm)and hold at the moment 8meg.slots 1 +2 are seperate slots and hold no more that 4 meg each.
many thanks for quick reply.
Originally posted by Reid:
Can you find a model number on the motherboard. Something sounds unusual to me. I can't find any 486 motherboard with three 72 pin SIMMs. Some have two 30 pin and one 72 pin, but an odd number seems to be just that, odd.

[grant99]

yep....seems that banks 1+2 (which are seperate simm slots)hold 4 meg max.i think this is true as i put the 8 meg ram into these slots and they only booted up to 3020meg in both slots.
bank 2+3(which are the same simm slot holds at the moment 8meg and boots this up fine.i'm just wondering if this is the only slot available for expansion?
Originally posted by ReddDogg:
Just a quick question, did you try putting the 16's in where the 4's were before, and leaving the 8 in there??? or even try all three slots with 16's??? Just curious.

[grant99]

thanks for the quick response.
the ram seems fine apart from two having"sd7228" and "94vo" on them.none boot up but i did find out (by using the existing simms that bank2+3(which are the same simm slot can hold at least 8meb but slots 1+4 can hold only 4meg each.i know cos i put the 8meg simm into both slots and it only booted up 3020meg.does this mean i can only expand memory in slot 2+3 which is the same slot.if so what should i do?
Originally posted by Paleo Pete:
I've never heard of a board with only 3 slots... This one only has 3???

Try the chips one at a time, only long enough to see if you get video, then shut down. One chip may be bad. Check the board, one slot should be marked bank 0 or bank 1. That's the first slot to use.

72 pin SIMM must be installed in pairs, which is why I was wondering about 3 slots...but you can try them one at a time, just long enough to see a picture.

Make sure you don't have the memory plugged in backwards. It's not easy, but can be done..

A 486 is an older machine, the memory, if newer, could easily be the wrong density and therefore incompatible, or could be the wrong access speed. If it's too fast, it might not work. That's the 6ns or 7ns speed, which should be the last number stamped on the chips.

Where did this new memory come from? Reputable source or online auction, mail order, etc? Could be you got Fast Page Mode or non-parity instead of EDO. And are you sure EDO is what your machine uses?

Also, memory is highly susceptible to ESD, or static electricity. If you handled it without being grounded first, it is possible it was fried the instant you touched it. When you touch a doorknob and get a shock, that's at least 2000 volts minimum. Computer components can be toasted by less than 100 volts, especially memory.

[Reid]

I could not find a manual for the 486-GAC-2, but the following link does have some limited info. It does indeed have three 72 pin sockets (It was more suprising to see the single 16 bit ISA slot). The board supports a maximum of 48M. http://www.mmtr.or.jp/~shcgf/fic/486/486-gac2.htm

More memory info came from: http://www.fic.com.tw/techsupport/faq/faqs486.htm#EDO
8. Can I use EDO DRAM or parity DRAM on a 486 motherboard?

486 motherboards are not capable of supporting EDO DRAM and parity DRAM due to chipset limitation. Use ordinary DRAM memory on your system. (E.g
non-parity DRAM).
******************
I hope this is what you need.



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rdrummond@thesimpsons.com

[grant99]

many thanks for all your help.

i really appreciate it.

i'll keep you informed as to the outcome when i gat the correct ram

once again....many thanks.

[xor_chad]

Howdy
Having 3 SIMM slots is not that odd for 486's.
The reason being is because they use a 32bit bus, not a 64bit like the Pentiums.
Pentiums had to couple two 32bit buses to get one 64bit transfer. Understand?
Depending on how old the MB i wold more than likely believe it to use EDO.
Parity memory was common on older MBs as so for FPM.
Hope this does some help. Laters...

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Chad Wilson
C++/ASM Programmer
PC Support Technician