August 5, 2003

BITS & BYTES

Here is a little technical information for the masses.  Do you ever wonder what the differences are in the way RAM is assembled?  Does 2x8, 4x16, and 16x64 make you glaze over and start drooling on your desk?  It is really very simple if you can stay awake long enough to read this.

 DRAM chip densities are described by their cell organization.  (A DRAM chip is a single one of the black chips found on a RAM stick)  The first number in the expression indicates the depth of the chip (in locations) and the second number indicates the width of the chip (in bits).  If you multiply the depth by the width, you get the density of the chip.  16x64=1,024.  Divide by 8 (there are 8 bits in a byte) and you get 128 Megabytes.

 A 2x8 configuration means the chip has 2 million locations deep and it has 8 bits in its width.  Therefore, it has 16 million cells that can hold 1 bit of data in each location.  Four of these chips totals 64 million memory cells (16+16+16+16=64) or 64 Megabits ( 8 Megabytes).

 If there are eight 64Mbit chips, it’s a 512Mbit module (64+64+64+64+64+64+64+64=512).  To determine how many Megabytes, divide the number of bits by 8.  In the case of the 512Mbit module, 512Mbits/8bits per byte =64MB.

 Eight bits equal 1 Byte

1 Megabit = 1 million bits

1 Megabyte is one million bytes or 8 million bits

Mb=Megabit or one million bits

MB=Megabyte, one million bytes or 8 million bits

 I have a chart that shows specific layouts of RAM modules and how densities can differ between the same size modules.  This situation arises daily at S&K.  There are so many people trying to do upgrades on older machines that don’t recognize higher density modules.  Our first recommendation is always update the bios.  It can make a big difference.  Secondly, determine what the density is of the existing RAM.  That always helps us in determining what to sell you.  If you don’t know how to figure it out we have equipment that will identify the configuration.  That doesn’t help most of you because you are out of town or out of state.  However, we can usually identify it with enough information from you as long as you have the module in hand when you call us.

 If this newsletter made you snooze, thank us for the nap time.  Otherwise, thanks for your attentiveness

 S&K