Memory 6 1 Section Objectives After completing this section you will be able to Differentiate between different memory technologies Plan for a memory installation or upgrade Install and remove memory chips Describe how memory works with the operating system Optimize memory for Windows based platforms Troubleshoot memory problems 6 2 Memory Overview Types of Memory RAM Random Access Memory is volatile memory found on the motherboard and stores the operating system the software applications and the data being used by all of the software ROM Read Only Memory is a non volatile type of memory that keeps data in chips even when the computer is shut off Types of RAM DRAM Dynamic RAM is less expensive but slower than SRAM It requires periodic refreshing of the electrical charges holding the 1s and 0s SRAM Static RAM is faster but more expensive than DRAM It is also known as cache memory or L2 cache 6 3 Memory Overview Memory Terms Refreshing Periodically rewriting information to the memory chip Nanosecond A billionth of a second Pipelining The process by which microprocessors and memory obtain computer software instructions in a timely fashion Cache Memory Can be found on the motherboard but normally is found inside the CPU Cache memory holds the most frequently used data so the CPU does not return to the slower DRAM chips to obtain the data 6 4 Memory Physical Packaging Types of Memory Packaging DIP Dual In line Package A chip that has a row of legs running down each side SIMM Single In line Memory Module Available in 30 pin and 72pin configurations DIMM Dual In line Memory Module 168 pin 184 pin and 240 pin configurations DDR DIMM 184 pin configuration and single notch on bottom RIMM Type of memory module used on Pentium 4 computers 6 5 Memory Physical Packaging Memory chips Memory Figure 6 1 6 6 Memory Physical Packaging 184 Pin DDR DIMM and RIMM Memory Figure 6 2 6 7 Planning the Memory Installation Key points for planning a memory installation Refer to motherboard documentation to determine what type of memory is supported Determine what features are supported Determine how much memory and how much of each module is needed Research prices Purchase memory modules 6 8 Planning the Memory Installation Memory Chip Technologies Technology to provide faster DRAM speeds FPM Fast Page Mode EDO Extended Data Out BEDO Burst EDO 6 9 Planning the Memory Installation Memory Features Methods of Error Checking Parity A method for checking the accuracy of data going in or out of the memory chips Non parity Memory chips that do not use any error checking ECC Error Correcting Code Uses a mathematical algorithm to detect up to four bit memory errors and correct one bit memory errors A computer system that uses parity must have parity memory installed 6 10 Planning the Memory Installation The Amount of Memory to Install Memory is one of the easiest upgrades to increase computer performance Amount of memory needed depends on Operating System Types of applications used How many applications the user wishes to have open at the same time Type of computer Maximum allowed by motherboard 6 11 Planning the Memory Installation The Amount of Memory to Install Common Memory Capacities DIMM Modules 256MB 512MB 1GB 2GB 4GB and 8GB RIMM Modules 64MB 128MB 256MB and 512MB Memory chips can have varying numbers Example 256 memory module showing 32Mx64 6 12 Planning the Memory Installation The Amount of Memory to Install The starting point for memory is determined by your operating system The number of application the user wishes to run simultaneously and the application function also affect the amount of memory needed In Windows XP access the System Information window to determine the amount of memory you have It is necessary to take the cover off of the computer and look at the motherboard to determine the number of slots available 6 13 Planning the Memory Installation The Amount of Memory to Install Common Computer Ports Table 6 5 6 14 Planning the Memory Installation How Much of Each Memory Type The motherboard manufacturer determines the number of memory slots what type of memory modules fit in each slot and the features the memory modules can have Single sided memory A memory module that the CPU accesses one at a time Double sided memory A memory module manufactured in a way that it has two memory modules in one container Dual channel memory The memory processing is handled more efficiently by the memory controller chip by handling two memory paths simultaneously 6 15 Planning for Memory Research and Buy Research and buying is one of the most confusing steps of memory installation upgrade A confusing aspect of purchasing memory is memory speed which can be represented in nanoseconds MHz or the DDR PC Rating Access time How fast information goes into a memory chip or is removed from the chip measured in nanoseconds CL rating column address strobe CAS latency The amount of time as measured in clock cycles that passes before the processor moves to the next memory address 6 16 Laptop Memory Types of Laptop Memory SO DIMM Small Outline DIMM or microDIMM Special smaller DIMM used in laptop computers SO RIMM Small Outline RIMM Special smaller RIMM used in laptop computers 6 17 Installing Memory Overview Installation Steps Determine which chip capacities can be used for the system Determine how much memory is needed Determine what capacity chips go in each bank 6 18 Installing Memory Overview Before removing or installing memory chips always refer to the documentation for you computer Use an anti static wrist strap when removing or installing memory chips 6 19 Removing Installing a DIP Chip Some ROM chips and memory chips found on devices are socked DIP chips Use a DIP chip extractor to remove a DIP chip from a motherboard but be careful not to bend the DIP chip legs A small flat screwdriver may also be used to remove DIP chips from a motherboard 6 20 Removing Installing a DIP Chip DIP Chip Removal Memory Figure 6 9 6 21 Removing Installing a DIP Chip To install a DIP chip align the notch on the DIP chip with the notch on the motherboard After ensuring that the legs are aligned with the socket press down into place on the motherboard 6 22 Installing a DIP Chip DIP chip installation Memory Figure 6 10 6 23 Removing Installing a DIMM RIMM To remove a DIMM or a RIMM push down on the outside edges of the DIMM s retaining tabs The DIMM RIMM lifts slightly out of the socket 6 24 Removing Installing a DIMM RIMM DIMM RIMM