RAM what a difference....

J

John Evans

New Member
#1
I have a 486 system that has 8-1MB 32Pin Simms. The system was working fine until one day during POST it came up with an error "on board parity error add(hex)=(0000:0002) System halted". The address I think is where bios is being loaded onto RAM.

I checked in CMOS to see if there is a RAM parity setting and couldn't find any. The label on the 32 pin simms "GM71C1000J80" seems to indicate non-parity simms.

Here's the kicker! Just for ha ha I installed a set of 30 pin 1mbx9P which I believe that the "P" indicates parity. IT WORKS!!!!

I don't get it, can someone tell me the difference between 30 and 32 pin and how to read RAM chip labels to tell weather or not these chips are Parity or non-parity.

I appreciate it BIG TIME guys.....
John
 
N

NUKE

New Member
#2
RAM WITH REAL PARITY HAVE ONE MORE CHIP (EXAMPLE: 9:pARITY, 8:NO PARITY).
OTHER WAY IS READING THE SERIAL # ON THE CHIPS,THE LAST # AFTER THE - IS RAM SPEED(EXAMPLE:324566-6),6 ARE 60ns ,7 ARE 70ns.
RAM WITH PARITY HAVE 60 ns SPEED.
 
A

Avatar

New Member
#3
Nuke is mostly correct.

The number of chips on a parity module is evenly divisable by 9. Exception: 3 chip 30pin SIMMs.

The number of chips on a non parity module is evenly divisable by 8. Exception: 2 chip 30min SIMMs.

Reading the density of a module is a real trick, and would require alot more explanation. If yuo REALLY want to know, email me.
 
A

Avatar

New Member
#4
Opps, forgot one thing. There is no such thing as a 32pin SIMM.

Standard Memory Vatiations:

30pin SIMM
64pin SIMM (RARE, AST usually)
72pin SIMM
72pin DIMM (SODIMM)
112pin SIMM (RARE, Apple usually)
144pin DIMM (SODIMM)
168pin DIMM
200pin DIMM
 

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