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RAM

RAM. Chapter 6. Overview. In this chapter, you will learn how to Identify the different types of DRAM packaging Explain the varieties of RAM Select and install RAM Perform basic RAM troubleshooting. Program Execution.

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RAM

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  1. RAM Chapter 6

  2. Overview In this chapter, you will learn how to Identify the different types of DRAM packaging Explain the varieties of RAM Select and install RAM Perform basic RAM troubleshooting

  3. Program Execution Program code is copied from your hard drive into RAM before it is executed

  4. Understanding DRAM Dynamic random access memory (DRAM) is the most popular type of electronic memory • Special type of semiconductor that stores ones and zeroesusing microscopic capacitorsand transistors • Single chip that can hold millions of these capacitor/transistor combinations • Limited width of 1, 4, 8+ bits

  5. Understanding DRAM Chips have historically been referenced with respect to their depth and width 256 K × 1 = 256 Kb 1 M × 4 = 2 MB 64 M × 8 = 64 MB You can't tell the width of chip visually

  6. Organizing DRAM DRAM is considered the standard Low cost, high speed, and able to store data in a relatively small package Many varieties of DRAM Early DRAM stored programs and data in 8-bit (1-byte) chunks of memory Individual chips were only 1-bit wide Had to link 8 together to provide 1-byte code

  7. Memory Controller Chip The memory controller chip (MCC) handles the flow of data from the RAM to the CPU MCC takes care of the physical access CPU doesn’t care if it’s one chip or eight chips!

  8. DRAM Sticks Individual DRAM chips were difficult to maintain An alternative was needed Put them on a stick

  9. The RAM of Your Ancestors Early RAM types were called Fast Page Mode (FPM) and Extended Data Out (EDO) Speed measured in nanoseconds Example: 72-pin SIMM

  10. SDRAM Synchronous dynamic RAM (SDRAM) is tied to the system clocks Synchronized with system clock Measured in MHz Comes on DIMM sticks SO-DIMMs for laptops

  11. SDRAM Speeds PC speed rating = Clock speed Clock Speed PC Speed Rating PC66 100 MHz PC100 PC133 133 MHz 66 MHz

  12. DIMM (Dual Inline Memory Module) This is the standard for SDRAM The 168-pin DIMM was very popular for desktops 144-pin SO-DIMMs (small outline) are used in laptops

  13. RDRAM RDRAM (Rambus DRAM) is a type of RAM Speeds of up to 800 MHz Comes on sticks called RIMMs 184-pin for desktops and 160-pin SO-RIMM for laptops Dual-channel architecture All slots must be populated: unused slots must have a CRIMM (continuity RIMM)!

  14. DDR SDRAM Double Data Rate DDR SDRAM doubles the throughput of SDRAM 184-pin DIMM packages (desktops)‏ 172-pin micro-DIMM and 200-pin SO-DIMM packages (laptops)‏ Wide range of speeds and naming conventions

  15. DDR Speeds PC speed rating = Clock speed × 2 (i.e., doubled) × 8 (i.e., 64-bit data bus) Clock Speed DDR Speed Rating PC Speed Rating 100 MHz DDR200 PC1600 133 MHz DDR266 PC2100 166 MHz DDR333 PC2700 200 MHz DDR400 PC3200 217 MHz DDR433 PC3500 233 MHz DDR466 PC3700 250 MHz DDR500 PC4000 275 MHz DDR550 PC4400 300 MHz DDR600 PC4800

  16. Dual-Channel Architecture Uses two sticks of RAM together to increase throughput Works only with paired RAM sticks

  17. DDR2 SDRAM Doubled the clock, increasing buffering Does not speed up core RAM, but just the I/O 240-pin DIMM (not compatible with DDR)‏

  18. DDR2 Speeds Clock Speed DDR I/O Speed DDR Speed Rating PC Speed Rating 100 MHz 200 MHz DDR2-400 PC2-3200 133 MHz 266 MHz DDR2-533 PC2-4200 166 MHz 333 MHz DDR2-667 PC2-5300 200 MHz 400 MHz DDR2-800 PC2-6400 250 MHz 500 MHz DDR2-1000 PC2-8000 • PC speed rating = Clock speed × 2 × 2 (i.e., doubled twice) × 8 (i.e., 64-bit data bus)

  19. DDR3 Double the rate of DDR2 240-pin DIMM – not compatible with DDR2 (as shown in the graphic) DDR2 (top) and DDR3 (bottom) sticks

  20. DDR3 Speeds Clock Speed DDR I/O Speed DDR Speed Rating PC Speed Rating 100 MHz 400 MHz DDR3-800 PC3-6400 133 MHz 533 MHz DDR3-1066 PC3-8500 166 MHz 667MHz DDR3-1333 PC3-10667 200 MHz 800 MHz DDR3-1600 PC3-12800 • PC speed rating = Clock speed × 2 × 2 × 2 (i.e., doubled three times) × 8 (i.e., 64-bit data bus)

  21. RAM Variations Double-sided sticks Latency Parity and error correction code Buffered/Registered Let's take a look at each one

  22. Double-Sided DIMMS Almost all sticks come as single-sided or double- sided Your motherboard may or may not be able to accept double-sided sticks

  23. Latency Latency Measure of RAM response time Shown as CLx (x =2 - 9) Higher the number, the higher the latency Check motherboard manual for latency limits

  24. Parity and ECC Parity is a rudimentary method of checking the data to see if errors exist No error correction, just detection ECC (error correction code) is a special type of RAM used by high-end systems Major advance in error checking on DRAM Can also correct many errors RAM sticks of any size can use the ECC DRAM, but it is most common as 168-pin DIMMs A motherboard must be designed to use ECC to take advantage of the ECC RAM

  25. Buffered/Registered DRAM Most motherboards support only four sticks of RAM More than four sticks present challenges for memory controllers To overcome these problems, buffering chips are added Buffering chips as intermediary between RAM and MCC

  26. Working with RAM What’s wrong with this picture?

  27. Working with RAM (continued) Avoid ESD damage Don’t touch pins or connectors directly

  28. Do You Need RAM? Two symptoms point to needing more RAM General system sluggishness, especially as more programs are opened Disk thrashing or excessive hard drive accessing,caused by excessive paging Note: Disk thrashing can also be caused by disk fragmentation

  29. System RAM Recommendations Operating System Reasonable Minimum Solid Performance Power User Windows 2000 128 MB 256 MB 512 MB Windows XP 256 MB 1 GB 2 GB Windows Vista 2 GB 4 GB 8 GB • Actual minimum requirements are much lower • Usually leads to slower computer and unhappy user

  30. Determining Current RAM in Windows XP My Computer Properties WINDOWS KEY-PAUSE/BREAK key Task Manager CTRL-SHIFT-ESC

  31. Determining Current RAM in Windows Vista Same as XP Computer Properties WINDOWS KEY-PAUSE/BREAK key Task Manager CTRL-SHIFT-ESC

  32. Getting the Right RAM Identify capacity What can the motherboard handle (look at the manual)‏? Identify empty slots If all slots are 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 to determine what you have Also shows latency

  33. Lab – Finding the Right RAM Upgrading RAM is the most common hardware upgrade that people do—and the easiest! You’ll need a motherboard manual and access to the Internet to complete this lab

  34. Lab – RAM for the PC Consult the motherboard manual to determine type and amount of RAM the system will support Go to one or more of the following Web sites to find the right RAM www.newegg.com www.tigerdirect.com www.frys.com www.bestbuy.com If you were going to upgrade the RAM, who has the best price?

  35. Mix and Match at Your Peril Mixing DRAM speeds can cause the system to lock up, leading to data corruption You can use faster DRAM than the motherboard recommends, but you won’t see an increase in performance You can put different speeds of DRAM in different banks as long as they are both faster than the speed specified

  36. Installing DIMMs Swing the side tabs away from upright Push the DIMM down somewhat hard… the two tabs should move back into place

  37. Installing RAM Checklist Get the proper RAM Handle on edges only Don’t touch contacts Power down the PC and unplug it Flip latches open Align RAM groove with slot Insert RAM straight into slot

  38. Inserting a DIMM

  39. Lab – Your Turn (Installing RAM) On your motherboard, remove and install the RAM The act of removing and putting back the RAM is called re-seating the RAM Unplug the PC Take appropriate ESD precautions Flip latches open Remove RAM Handle edges only Don’t touch contacts Align RAM groove with slot Insert RAM straight into slot

  40. Serial Presence Detect Serial presence detect (SPD)‏ Reports the size, speed, data width, and voltage of the installed RAM MCC knows what to do CPU-Z shows SPD data

  41. The RAM Count Shows at boot Counts addressable RAM and reports it Remember the subtle differences between counting in binary and decimal-- 512 MB does not equal 512 million exactly

  42. Installing SO-DIMMs in Laptops Make sure the system is off No AC connection Remove all batteries Remove the panel or lift the keyboard Slide the pins into position and then snap the SO-DIMM down into the retaining clips

  43. Memory Errors Appear as Parity errors, ECC error messages, system lockups, page faults, and BSoD Real memory errors “Parity error at xxxxx” If xxxxx is consistently the same, you have a bad RAM stick. Phantom errors Random memory addresses Due to power issues, dust, and heat Page fault

  44. Non-Maskable Interrupt Blue Screen of Death (BSoD)

  45. Testing RAM Hardware RAM testing devices can be used to troubleshoot errors Memtest86 is a freeware tool that can be used to test RAM Vista comes with a memory testing utility on the install disc

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