V 2012.13. 2 Avon High School Tech Crew Agenda Old Business New Business Week 2 Meeting Review Week 3 Topics: –Intro to Memory –Continue to trouble shoot

V2012.13

2Avon High School Tech Crew

Agenda

• Old Business• New Business• Week ‘2’ Meeting Review• Week 3 Topics:

– Intro to Memory– Continue to trouble shoot our PC


Old Business

• Sub-groups– Graphics– Web Design– App Development– Other?

• Scorer’s table job• Email me with interest!• Fundraising• Remember … participate!

– Read email, polls, requests, etc.


New Business

• District Tech Department Help– Install Office 2010– Repair Computers

• Contact Info– Request your name/year

• Comments on Twitter• T-Shirts

– Limited sizes/colors


Week 2 Meeting Review

• Intro to Computer Repair– What did you think?– Any follow-up questions?

• Our non-working PC …– Did you answer the poll question?


Intro to Memory


Intro to Memory

• Common Terms• Common Types• How it works• Resources


First, Some Common Terms

Term Definition Purpose

Volatile Computer memory that requires power to maintain the stored information

RAM

Non-Volatile Computer memory that can retain the stored information even when not powered

ROM

DIMM Dual in-line memory module Difference between SIMMs and DIMMs is that DIMMs have separate electrical contacts on each side of the module


Common Types of Memory

Type Definition Purpose

BIOS Basic Input/Output System Boots firmware, POST

ROM Read-only memory Used to store firmware

Cache Smaller, faster memory Reduce average time to access main memory (L1, L2, L3)

RAM Random-access memory Data accessed quickly in random order, in same amount of time

DRAM Dynamic random-access memory Data fades unless the capacitor charge is refreshed, very high densities

SRAM Static random-access memory Holds charge, typically faster, less dense, more expensive

SDRAM/DDR Synchronous dynamic random-access memory

Synchronized with the computer's system bus (DDR1, DDR2, DDR3)


DDR (SDRAM) Memory

• Double Data Rate• Two data transfers

per cycle• Higher bandwidth

– DDR3 has the ability to transfer data at twice the rate of DDR2

• Uses less power (30%)


Common Types of Memory

Type Definition Purpose

Flash Non-volatile computer storage chip that can be erased and reprogrammed

Used in USB drives, memory cards, solid-state drives

SGRAM/GDDR Synchronous graphics random-access memory, Graphics Double Data Rate

Specialized form of SDRAM for graphics adaptors (GDDR3, GDDR4, GDDR5)

Solid State/SSD Solid-state drive, no moving mechanical components, retains data without power

Data storage device


DDR vs GDDR

• GDDR is built for much higher bandwidth, thanks to a wider memory bus

• GDDR has lower power and heat dispersal requirements compared to DDR, allowing for higher performance modules, with simpler cooling systems

• DDR1, DDR2, and DDR3 have a 64 bit bus (or 128 bit in dual channel). GDDR3, comparatively, commonly uses between a 256 bit bus and 512 bit bus, or interface (across 4-8 channels)


DRAM vs SSDs

• DRAM is used to run stuff• SSDs are where you store stuff


Memory Hierarchy


Memory Hierarchy


Why so many types of memory?

• Different pieces of a computer system have different requirements for speed, size and cost

• Computer designers have solved the cost problem by "tiering" memory

• Using expensive memory in small quantities and then backing it up with larger quantities of less expensive memory


So, how does memory work?

• The basics …• Each memory ‘cell’ is comprised of:

– Transistor– Capacitor

• Each cell can hold 1 bit of information• Cell contains a data input line, a data output line,

a Read/Write line and a select line – The select line activates the cell and Read/Write line

tells it either to output its contents or store what is at its input



• Cells are organized in a grid pattern, rows columns

• Data (‘line’) inputs and outputs for each cell are connected together to form an ‘array’

• Data is written to a specific row and column of the array, defined as the ‘binary address’

• CPU can access the data from that specific address



• Data lines from multiple memory chips are grouped to form a ‘data bus’

• Data bus has the following characteristics:– Bus width refers to the number of bits that can be

sent to the CPU simultaneously– Bus speed refers to the number of times a group of

bits can be sent each second– Bus cycle occurs every time data travels from

memory to the CPU



• Memory Controller– Manages the flow of data going to and from the main

memory– Contain logic necessary to read and write to DRAM,

and to "refresh" the DRAM– It can be a separate chip or integrated into another

chip (like the CPU)– Part of the ‘Northbridge’

• Located closest to the CPU (or on the CPU) and controls the fastest components on the motherboard: the CPU, video card slot and RAM


When/Why would you install memory?

• To improve performance– O/S, apps getting larger

• To prevent disk ‘swapping’– Windows creates ‘virtual RAM’ – In the form of ‘pagefile.sys’ on your hard drive

• But there are other factors that impact performance …


Summary

• Different types of memory address different needs

• Used in almost every phase of a computer system

• At a high level, memory is comprised of cells, arrays, data bus

• Operated by a memory controller which communicates with the CPU

• Generally helps improve performance


Questions/Comments?

Scott [email protected]


Troubleshooting


Our Non-Working PC …

• Dell 2400• No output to screen• Blinking amber light (power)• Fans are not spinning

• What would you do next?• Ideas …?

Documents

V 2012.13. 2 Avon High School Tech Crew Agenda Old Business New Business Week 2 Meeting Review Week 3 Topics: –Intro to Memory –Continue to trouble shoot