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In article <3155@amsaa-cleo.brl.mil> cgaeth@amsaa-cleo.brl.mil (Christopher Gaeth) writes:

 > I would like to know the difference between SIMM chips and DRAM 
 > chips.  I'm planning on adding more memory to my machine and it takes SIMMS
 > and I was wondering why they are so much more expensive (10X's as much).

SIMM's cost much more than DRAM chips in terms of dollars per unit, but
that's because SIMM's provide more RAM per unit.  A SIMM (Single Inline
Memory Module) bank contains either eight or nine (depending on whether
your machine wants parity) DRAM chips.

Something which is rather confusing is the abbreviation "b".  For DRAM
chips, the abbreviation stands for bits, but for SIMM's the abbreviation
stands for bytes.  A machine with eight 1Mb SIMM's has eight times the
memory of a machine with eight 1Mb DRAM chips.

Commonly seen labels for RAM expansion parts:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1Mbx9 SIMM	provides one megabytes of memory
1Mbx8 SIMM	one megabyte
256Kbx9 SIMM	two hundred fifty-six kilobytes
256Kbx8 SIMM	two hundred fifty-six kilobytes
1Mb DRAM	one megabit = one hundred twenty-eight kilobytes
256Kb DRAM	two hundred fifty-six kilobits = thirty-two kilobytes

[Additional numbers which are multiples of ten running from about 60 to
120 are likely to indicate the access speed in nanoseconds.]

Hope that helps clear up any confusion.

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