Introduction to Computers

Factors in processor Performance Clock speed Most vital, dictates instructions executed per second Word Size Dictates number of bits per instruction & usable RAM Front side bus (FSB) speed Speed of data pathway between memory & processor Cache size Ability to hold latest instructions/data in fast memory Number of processor cores Allows multiple tasks to execute simultaneously

Clock speed A microprocessor is a single integrated circuit or chip designed to process instructions Clock speed determines number of instructions executed each second by processor One instruction executes at each “tick” of the clock Clock speeds expressed in gigahertz (GHz) 1 GHz is a billion ticks in a second Higher clock speeds mean faster execution

Word size Word size determines how many bits the processor can accept with each instruction PC’s went from 32 to 64 bit processors recently Allows addressing of RAM in excess of 4GB But many older 32 bit processors remain in use Larger word size means faster execution Minor performance increase, not twice 32 bit speed Lots of 32 bit application software still in use But Windows is a fully 64 bit operating system

Front side bus Front side bus is the pathway that moves data and instructions from memory to processor Like clock speed, FSB speeds are typically expressed in gigahertz (GHz) A smaller FSB speed means data takes longer to get from memory to processor A slow FSB can drag down processor performance

Cache size Cache refers to very fast memory integrated into the processor chip The larger the cache size the better Data and instructions transferred from RAM to the processor are stored in cache When the processor needs data or instructions it always checks for it in cache first If already in cache, there’s no need to retrieve the data from RAM, increasing performance

Multicore Processors Multi-core processors are a recent development Designers hit several physical limitations in trying to improve processor performance Designing multiple processors on one chip is a way to circumvent these limitations Software must be redesigned for multi-core Operating systems take advantage of multi-core Much application software does not at this time Multi-core processor gains mostly in multi-tasking

The instruction set Every processor has an instruction set The list of instructions that processor can perform This is built in or hardwired into the chip Processors are grouped into families Processors in a family are compatible with other processors in that family Members of a family use the same instruction set The processor executes instructions found in a computer program

Processor families The X86 family The ARM family Includes processors from two competing firms, Intel and Advanced Micro Devices (AMD) Mac & Windows PC’s use this family of processors Originally based on Intel processor architecture The ARM family Reduced instruction set approach uses less power Designed from the start to be highly power efficient Intended for and used with mobile Android devices PowerPC family not used in personal computers

The Intel & AMD processor Lines High end personal computer processors Intel – Core i series… Core i3, Core i5, Core i7, and Core i9 AMD – Ryzen and FX series Midrange priced processors Intel – Pentium AMD – Athlon and A series Budget processors Intel – Celeron AMD – Sempron High end server/high performance computing Intel – Xeon or Itanium AMD - Opteron

ARM Processors for mobile devices Some widely used processors found in Android smart phones and tablets are: Qualcomm – Snapdragon processor Intel – Atom processor Samsung – Exynos processor Nvidia – Tegra processor Apple makes its own proprietary processors solely for use in the iPhone & iPad But uses the X86 family for its Mac computers

High-end versus budget Budget processor lines are great for most users Most users have fairly basic needs Web browsing, email, music, etc. The more sophisticated your needs, the more the need for the high-end processor Gaming in particular needs a high end processor Celeron is based on high-end processors but: Runs at a lower clock speed Has less cache memory Has a slower front side bus (FSB)

Random Access memory Random access memory (RAM) is main storage Holds anything needed for current processing This includes both data and instructions As you enter text into a Word document, the characters you type are stored in RAM Operating system instructions held in RAM as well RAM is volatile, requires power to hold data Each RAM address consists of 8 sets of on/off switches called capacitors

Current RAM requirements Most new computers have 4 to 12 GB of RAM Very low end computers may have 2GB Computers designed for gaming often have 16GB Amount of RAM needed depends on software used and number of programs run concurrently Easy to purchase and install additional RAM Can’t run out of RAM If RAM fills, computer will use virtual memory

Virtual memory Virtual memory is main storage space formatted to “look” like RAM If RAM fills, the least frequently used task is swapped out to virtual memory There’s a noticeable time delay when this happens Main storage is incredibly slow compared to RAM Task automatically swapped back in if reactivated Another noticeable time delay when swapping in Minimize use of virtual memory

Different types of RAM Computers use SDRAM almost exclusively Different types of SDRAM include DDR3 and DDR4 RAM has different access speeds Sometimes measured in nanoseconds A nanosecond (1 ns) is a billionth of a second If nanoseconds used, a lower number is faster More commonly measured in GHz If GHz used, a higher number is faster

Purchasing memory Be sure to buy RAM compatible with your PC It’s often best to check with the manufacturer Manufactured as individual chips called DIPs DIPs soldered on a circuit board called a DIMM Stands for Dual In-line Memory Module Memory is sold and installed as a DIMM Easy to install, plugs into a slot on the motherboard

A common RAM Upgrade issue Say you have 4GB of RAM with an 8GB capacity So to upgrade, you need another 4GB, right? Not necessarily PC with 8GB capacity may have 2 DIMM slots If you already have 4GB of RAM, often times it’s installed as two 2 GB DIMMs, taking up both slots So you must buy two 4GB DIMMs to maximize RAM You end up throwing out 4GB of memory because it came as two 2GB DIMMs instead of one 4GB DIMM

Read only memory ROM is permanent and non-volatile Holds instructions required in boot up process RAM empty when computer is started, so ROM is the source of initial boot up instructions Provides instructions for computer to find and begin loading operating system from hard disk Only way to change the instructions on a ROM chip is to replace the chip

Storing configuration settings Due to the volatile nature of RAM, cannot store configuration settings there These settings must be maintained with power off ROM not an option, must be able to change configuration settings change Configuration settings stored in an EEPROM Electrically erasable programmable read-only memory EEPROM an early version of today’s flash memory

What do these computers cost? Computer #1 - 15.6 inch display, non-touch Intel Celeron processor, 2.48 GHz, 2MB Cache 4GB DDR3 at 1.6 GHz, Up to 8GB 500GB Hard Drive, 5400 rpm Computer #2 – 15.6 inch 2-in1 touch display Intel Core i7, 3.5 GHz, 4MB Cache 12GB DDR4 at 2.4 GHz, Up to 16GB 512GB Solid State Drive $299 $979