1. Memory systems Unit objectives: • Describe the function of memory and differentiate among various types of memory chips • Differentiate among the various memory packages • Install RAM into a system while handling it properly and meeting your PC’s installation requirements • Monitor memory usage • Troubleshoot memory problems

2. Topic A • Topic A: Memory • Topic B: Memory packaging • Topic C: Memory installation • Topic D: Memory monitoring • Topic E: Memory troubleshooting

3. Memory • RAM: random access memory • Working area for data during processing • Need sufficient RAM for • Performance • Software support • Quality of RAM is important

4. Measuring memory • Cells • Store a single bit of data • 0 or 1 • Represents on/off or yes/no • Measurement units • Bit • Nibble = 4 bits • Byte = 8 bits • Word = based on CPU • 32-bit processor: 32-bit word • 64-bit processor: 64-bit word

5. Larger memory units • Byte (B) = 8 bits • Kilobyte (KB) = 1024 bytes = 210 bytes • Megabyte (MB) = 1024 KB = 220 bytes • Gigabyte (GB) = 1024 MB = 230 bytes • Terabyte (TB) = 1024 GB = 240 bytes

6. Memory types • Classify memory as: • Volatile vs. non-volatile • Static vs. dynamic • Asynchronous vs. synchronous

7. Volatile vs. non-volatile memory • Volatile: Loses contents without power • Non-volatile: Keeps contents without power

8. Dynamic vs. static memory • Dynamic (DRAM) • Must be continually refreshed • Inexpensive • Physically small chips • Static (SRAM) • Refreshing not required • More expensive • Larger • Faster • Typical uses • Main system memory: DRAM • Cache memory and CMOS: SRAM

9. Asynchronous vs. synchronous • Asynchronous • Not synchronized to system clock • Consistent time to access and read data • Synchronous • Synchronized to system clock • Accesses data and returns in one or more clock cycles • SDRAM faster than ADRAM

10. Memory access types continued

11. Memory access types, continued

12. Access time • Latency • Memory speed • Nanoseconds vs. megahertz • Overall speed • Doesn’t include latency • Bandwidth

13. Speed ratings

14. Activity A-1 Identifying memory characteristics

15. Topic B • Topic A: Memory • Topic B: Memory packaging • Topic C: Memory installation • Topic D: Memory monitoring • Topic E: Memory troubleshooting

16. Packaging • Early PCs used individual DRAM chips continued

17. Packaging, continued • Package • Small circuit board • More commonly called a module • Installed in slot • Module contains • Memory chips • Connecting wires • Support chips • Pins or edge contacts

18. Single- and double-sided modules • Early DRAM had chips on just one side • Double memory by placing chips on both sides • Double-sided modules have two rows of pins at bottom • Pins on front aren’t connected to pins on back • Number of chips no longer has a 1:1 chip-to-bit limit

19. Package types • SIMM 30-pin – ADRAM • SIMM 72-pin – ADRAM • DIMM 168-pin – SDR SDRAM • DIMM 184-pin – DDR SDRAM • DIMM 240-pin • DDR2 • DDR3 • RIMM • 184-pin – 16-bit • 232-pin – 32--bit continued

20. Package types, continued • MicroDIMM 144-pin • SODIMM 144-pin – SDR SDRAM • SODIMM 200-pin • DDR • DDR2 • SODIMM 204-pin – DDR3 SDRAM

21. Modules and chips • PC100 and PC133 use SDRAM • PC1600, PC2100, PC2700, and PC3200 use DDR SDRAM • PC2-3200, PC2-4200, PC2-5300, PC2-6400, and PC28500 use DDR2 SDRAM • PC3-6400, PC3-8500, PC3-10600, and PC3-12800 use DDR3 SDRAM

22. Memory error recovery • Parity — Detects an error • Even • Odd • Mark • Space • ECC — Detects and corrects an error • Desktop memory — No parity or ECC • Server memory — Often includes parity or ECC

23. Parity 8 chips, no parity 9 chips, supportsparity

24. Activity B-1 Comparing RAM packaging

25. Topic C • Topic A: Memory • Topic B: Memory packaging • Topic C: Memory installation • Topic D: Memory monitoring • Topic E: Memory troubleshooting

26. Memory installation considerations • Banking requirements • Proper handling techniques • Slot insertion techniques • Safe storage • BIOS configuration

27. Banking requirements • Install memory in groups called banks • Bank might include 1, 2, or 4 slots • Must fill every slot in a bank • Might have to use same type and speed of memory in every slot • Leave extra banks empty • With DRDRAM, install continuity modules • Dual-channel architecture

28. Proper handling • Unplug computer before opening it • Dissipate static • Move around as little as possible • Always handle modules by their edges

29. Inserting memory modules SIMM • Insert module at 45-degree angle • While pushing into slot, move module to fully vertical or horizontal position. Clips should engage automatically when module is fully seated DIMM • Spread retaining clips before insertion • Insert the module straight into the slot, perpendicular to the motherboard • Push firmly until the retaining clips snap into place on either side

30. Removing a module SIMM • Gently release the retaining clips at both ends of the module • Move the module to a 45-degree angle if it doesn’t do so automatically • Remove the module DIMM • Release the retaining clips on both ends of the module • Remove the module by pulling it straight up from the slot

31. CMOS configuration • BIOS checks memory at boot • Compares actual memory with CMOS entry • Follow prompt to update CMOS entry

32. Activity C-1 Adding memory to a desktop computer

33. Notebook memory • Location varies from notebook to notebook • Refer to documentation • Shut down notebook, unplug cord, and remove battery

34. Shared video memory • Main system memory shared with video circuitry • No dedicated video memory • Reduces cost • Uses less power; generates less heat • Not all RAM is available to OS and applications (does not show as present) • Slower than dedicated video memory • Add more system memory to increase performance

35. Activity C-2 Adding memory to a notebook computer

36. Memory in handheld computers • Expandable memory, a feature of more expensive handhelds • Some use modules similar to those in notebooks • Most use memory cards similar to those in digital cameras • Have a slot for inserting a flash memory card • Consult the manual

37. Activity C-3 Adding memory to a handheld computer

38. Topic D • Topic A: Memory • Topic B: Memory packaging • Topic C: Memory installation • Topic D: Memory monitoring • Topic E: Memory troubleshooting

39. Task Manager • Windows GUI utility • Provides information on processes running • Version available in all Windows OSs • Windows 9x/Me Program List • Windows NT/2000/XP/Vista/7 Task Manager • Access: • Ctrl + Alt + Delete • Right-click empty space in the taskbar and choose Task Manager • Ctrl + Shift + Esc

40. Performance tab indicators • CPU Usage • CPU Usage History • Memory (7/Vista) • Physical Memory Usage History (7/Vista) • PF Usage (XP/2000) • Page File Usage History (XP/ 2000) continued

41. Performance tab indicators, continued • System (7/Vista) • Totals (XP/2000) • Physical Memory • Commit Charge • Kernel Memory • Summary data

42. The Performance tab

43. Activity D-1 Monitoring memory usage

44. Virtual memory

45. Optimizing the page file • On boot partition by default • Determined by amount of RAM • Size automatically increases or decreases for best performance • Can manually override the settings • Page file size range: • RAM × 1.5 to 3.0 • System’s peak commit value • Can move file to different hard disk

46. Changing page file size • In Windows 7/Vista, click Start, right-click Computer, and choose PropertiesIn Windows 2000 /XP, right-click My Computer and choose Properties • In Windows 7/Vista, click Advanced system settingsIn Windows 2000/XP, activate the Advanced tab 3. In the Performance section, click Settings, and then activate the Advanced tab 4 In the Virtual memory section, click Change 5 Clear Automatically manage paging file size for all drives 6 Select Custom Size, and set the initial and maximum size

47. Activity D-2 Changing the size of the Windows page file

48. Topic E • Topic A: Memory • Topic B: Memory packaging • Topic C: Memory installation • Topic D: Memory monitoring • Topic E: Memory troubleshooting

49. Memory testing • POST not sufficient • Use testing utility • Memtest86 — Free, open source • Microsoft Windows Memory Diagnostic — Free, unsupported • Boot from floppy or CD

50. Memory-related problems • 201 BIOS error code at boot time • Parity error message • Computer randomly freezes (locks up) or crashes • Wrong amount of memory reported by the BIOS • Windows reports Page Fault or Exception errors • Random crashes, corrupted data, strange application behavior