486

[sidney]

A friend of mine has a 486,which he is trying to upgrade the memory. He has 4mb on board,4 one mb strips & 4 four mb strips but it is only registering 12mb. In the manual it says about entering the values for extended memory but we do not know what these are. We have checked all the strips one at a time and they all register at there correct size but when all together 12mb is as far as it goes. Any help would be very much appreciated.

[KillerBug]

Are you sure the 4 4mb sticks are not 1mb, 8 1mb sticks and 4mb on board=12mb.

[Gene C.]

Most 486 machines that use 72 pin simms come with 4 MB standard memory. (One 4 MB 72 pin simm), and usually come with (2) 72 pin simm banks of one socket each (2 sockets total), or (4) 72 pin simm banks of one socket each (4 sockets total). You can install one 72 pin simm at a time on a 486 machine. Many 486 systems use parity 4 megabyte (1x36), 8 megabyte (2x36), or 16 megabyte (4x36) simms. If you install non-parity 4 megabyte (1x32), 8 megabyte (2x32), or 16 megabyte (4x32) simms in a system that needs parity it will not function properly. Most 486 motherboards are only capable of handling 1, 4 and 16 meg modules. Gateway 486's, Dell 486's and AST 486's are among the machines with these limitations. These machines will not read 8 meg modules at all, or at best will only read 4 megabytes. Consult your motherboard documentation or contact your manufacturer to find out if your 486 can use 8 meg modules.

* Parity is a feature that is built into parity SIMM modules, which most IBM 386 and 486 machines use to check the memory for errors. All Apple machines use non-parity memory. If you install non-parity simms in a system that needs parity it will not function properly.

*Most 386 and 486 machines require 80 nanosecond or faster modules. You can't use anything slower in these machines (e.g. 90ns or 100ns). These machines can usually accept 80, 70, or 60ns chips. You can check the speed of your current chips by checking the model number on the DRAM chips. At the end of the model number there should be a -80 for 80ns, -70 for 70ns, or -60 for 60ns.

or you might want to check here. but, I think killerbug is right on that one. http://www.pcguide.com/ts/x/comp/ram/index.htm

[welsh wizard]

tell him to try swapping the 4 meg sticks to simm 0 and 1 meg to simm 1 if this doesn't work you will find either they are not 4meg sticks, one of the 4 meg sticks could have fault (unlikly as it would nor pull down bank) or they are not 4meg sticks http://www.sysopt.com/forum/frown.gif
WW

[GVolosky]

Post some mobo numbers and BIOS ID and we can narrow it down further...