2n x m n address bits = 2n (address line) m is the “width” of the data path m data bits/word/ paragraph or the

word length Typical values:

› n: 16, 17, 18, 19, 20, 21, 22,……… etc.› m: 8, 16, 32, 64 ONLY

number of words in the Memory = 2#addressline

Ex: the number of words in the memory =

1M word = 220 word the number of address line= 20 bit

address line

If the memory have 10 address line and the “width” of the data path is 32 data bit, determine the number of words and size of the memory .

How many address lines must be used to access 2048 bytes of memory if the word length is 8 bit?

Two Symptoms point to the need for more RAM in a PC:› general system sluggishness: running

programs seem to stall and move slowly.› Excessive hard drive accessing.

MyComputer Properties› Windows key &

Pause/Break

Task Manager› Ctrl & Shift & Esc

Identify capacity› What can the motherboard handle (look at the manual)

Identify empty slots› If all slots filled, you’ll have to pull some out› For example, pull out 256 MB sticks to add 512 MB

sticks

CPU-Z is a great tool tell you what you have› Also shows latency

Serial Presence Detect (SPD) chip› This reports the size, speed, data width and

voltage of the installed RAM to the BIOS› Can be read from BIOS› CPU-Z shows SPD data

The RAM Count› Part of Power On Self Test (POST)› Counts addressable RAM and reports it› Remember the subtle differences between

counting in binary and decimal 512MB does not equal 512 million

exactly.

All motherboards can handle different capacities.

You can use faster DRAM than the motherboard recommends but won’t see an increase in performance.

Mixing DRAM speeds can cause the system to lock up every few seconds or every few minutes leading to data corruption.

You can put different speeds of DRAM in different banks as long as they are both faster than the speed specified

Very sensitive to ESD(Electro-Static Discharge)

Use an anti-static wrist strap Keep your fingers off the pins If you mix DRAM speeds the system may

lock up

Swing the side tabs away from upright

Push the DIMM down somewhat hard – the two tabs should move back into place

Make sure the system is off› No AC connection› Remove all batteries

Remove the panel or lift the keyboard

Slide the pins into position, snap the SO-DIMM down into the retaining clips

IT TechnicianIT Technician

Troubleshooting RAMTroubleshooting RAM

Appears as:› Parity errors, ECC error messages, system lockups,

and page faults and BSOD There are two different types of parity error:

1.Real Memory Errors “Parity error at xxxxx” If xxxxx is consistently the same, you have a bad RAM

Stick.

2.Phantom Errors Random memory addresses Due to power issues, dust, heat

A halt before the RAM check could indicate improperly installed RAM

Hardware RAM testing devices can be used to troubleshoot errors

An economical option is to replace the existing sticks with new ones

MemTest32 is a freeware tool that can be used test RAM

After installing the new RAM, if the RAM is not recognized by your system, or if you get a long beep or sequence of beeps at startup, you'll have to do some troubleshooting.

Purchasing the wrong memory Installing it incorrectly Damaging the memory module by

handling it improperly.

The modules should be secure in their slots, lined up properly with the notches in the slot, should fit properly, and the retaining clips or ejector clips, if they exist, should be firmly secured. When this is achieved, the memory is said to be seated correctly.

If multiple modules are installed, you can also try switching their places on the motherboard. Put module 1 in slot 2, and module 2 in slot 1. Finally, try installing a single module in slot 1 (making sure it is enough RAM to successfully start the computer, at least 128 MB), restart your computer, and verify that the memory is recognized, remove it, and do the same with the other modules.

You should visit the manufacturer's Web site. Most sites have troubleshooting Web pages, articles on resolving known issues, and information about defective RAM and returning it if it doesn't work.