Course ILT Memory systems Unit objectives Describe the function of memory and differentiate between different types of memory chips Differentiate between different memory packages Test memory with a memory testing application and troubleshoot memory problems

Course ILT Topic A Topic A: Memory Topic B: Memory packaging Topic C: Memory troubleshooting

Course ILT Memory RAM = Random Access Memory Working area for data during processing Having sufficient RAM is critical –Performance –Software support Quality RAM is critical

Course ILT Measurement units Bit Nibble = 4 bits Byte = 8 bits Word = based on CPU –Pentium 4: 32-bit processor : 32 bit word

Course ILT Larger units Byte (B) = 8 bits Kilobyte (KB) = 1024 bytes Megabyte (MB) = 1024 KB = 1,048,576 bytes Gigabyte (GB) = 1024 MB = 1,073,741,824 bytes Terabyte (TB) = 1024 GB or 1,099,511,627,776 bytes

Course ILT Memory types Classify memory as: –Volatile vs. non-volatile –Static vs. dynamic –Asynchronous vs. synchronous

Course ILT Volatile vs. non-volatile memory RAMVolatile Random access memory CMOSVolatile Complementary metal oxide semiconductor ROMNon-volatile Read only memory PROMNon-volatile Programmable read only memory EPROMNon-volatile Erasable programmable read only memory EEPROMNon-volatile Electronically erasable programmable read only memory FlashNon-volatile

Course ILT Dynamic vs. static memory Dynamic (DRAM) –Must be continually refreshed –Inexpensive –Small Static (SRAM) –Refreshing not required –More expensive –Larger –Faster

Course ILT Asynchronous and synchronous Asynchronous –Not synchronized to system clock –Consistent time to access and read data Synchronous –Synchronized to system clock –Access data and return in one or more clock cycles SDRAM faster than ADRAM

Course ILT Memory access types DRAMDynamic RAM Older technology FPMFast Page Mode Improved over DRAM VRAMVideo RAM Dual port, optimized for video EDOExtended Data Out Improved over FPM BEDOBurst Extended Data Out Adds pipelining to EDO ADRAMAsynchronous DRAM Not synchronized to the system clock SDRAMSynchronous DRAM Interleaving permits overlapped requests DRDRAMDirect Rambus DRAM 16-bit memory bus and two transfers per clock cycle DDRDouble Data Rate Double transfer rate of SDRAM with two transfers per clock cycle DDR2Double Data Rate 64 bits per transfer to double DDR performance

Course ILT Access time Latency Memory speed –Nanoseconds vs. megahertz Overall speed –Doesn’t include latency –Doesn’t consider bus speed Bandwidth

Course ILT Speed ratings

Course ILT Activity A-1 Identifying memory characteristics

Course ILT Topic B Topic A: Memory Topic B: Memory packaging Topic C: Memory troubleshooting

Course ILT Packaging Individual chips Package –Memory chips –Connecting wires –Support chips –Pins or edge contacts

Course ILT Individual chips

Course ILT SIMM

Course ILT Package types

Course ILT Memory error recovery Parity—detects an error ECC—detects and corrects an error Desktop memory—no parity or ECC Server memory—often includes parity or ECC

Course ILT Parity 9 chips, supports parity 8 chips, no parity

Course ILT Activity B-1 Comparing RAM packaging

Course ILT Topic C Topic A: Memory Topic B: Memory packaging Topic C: Memory troubleshooting

Course ILT Task Manager Windows GUI utility Provides information on currently running processes Version available on all Windows operating systems –Windows 9x/Me Program List –Windows NT/2000/XP Task Manager

Course ILT Performance tab indicators CPU Usage CPU Usage History PF Usage Page File Usage History Totals Physical Memory (K) Commit Charge (K) Kernel Memory (K) Summary data

Course ILT The Performance tab

Course ILT Activity C-1 Monitoring memory usage

Course ILT Activity C-2 Adjusting the Windows page file size

Course ILT Memory symptoms 201 BIOS error code at boot time Parity error message Computer randomly freezes or crashes Wrong amount of memory reported by the BIOS Windows reports General Protection Fault, Page Fault, or Exception errors Random crashes, corrupted data, strange application behavior

Course ILT Activity C-3 Troubleshooting memory

Course ILT Unit summary Described the function of memory and differentiated between different types of memory chips Differentiated between different memory packages Tested memory with a memory testing application and resolved memory problems