CS100 Study Guide - Fall 2018, Comprehensive Midterm Notes - Central Processing Unit, Random-Access Memory, Operating System
12 Oct 2018
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CS100
MIDTERM EXAM
STUDY GUIDE
Fall 2018
A computer is an interface where the mind and body can connect with the universe and move bits of it
about
Hardware Components
1. Central Processing Unit (CPU)
a. Basic operations
i. Arithmetic (addition, subtraction, division, etc.)
ii. Comparisons (greater than, less than, equal)
iii. Logic (and, or, not)
iv. Data movement
v. Control flow (what to do next)
b. A lot can be accomplished with these operations at a very fast pace
c. Each CPU has its own machine language used to give it instructions
i. Instructions for one CPU typically do not work on another
d. Similar to engine of a car
i. Important qualities include model, make and capacity
• Some may consider colour, size, and features
e. Characteristics of the CPU
i. Model and make
• Will determine characteristics of the CPU
ii. Speed
• Measured in Gigahertz (GHz)
• Billions of operations per second
iii. Number of cores
• Usually has several processors or cores
iv. Power consumption
• Number of cores affect power consumption
• Some processors can slow down or switch to a "low battery mode"
v. Cache
• Fast, short-term memory built into the CPU
• 100 times faster than primary memory
• Big cache is better
2. Primary Memory and Secondary Storage
a. Primary memory
i. Main memory, also known as RAM (random access memory)
ii. Working space of the computer, stores everything that is done (executing, displaying,
calculating)
iii. Information on secondary memory must be copied onto the primary memory before it
can be used
• Saving a file copies it back to the secondary memory
• Some computers can hibernate, allowing contents on the primary memory to be
saved on secondary storage while power is lost
iv. Not permanently saved
• Primary memory is initially empty when the computer is turned on
• Computer boots up by running a program called a "boot loader"
• Stored on the ROM (read-only memory)
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• Boot loader copies the operating system from secondary storage to primary
memory so it can be run
• Operating system and start up programs are loaded into primary memory and
computer becomes useable
b. Secondary storage
i. Long term (permanent) storage
ii. Hard drives, flash drives, CDs, DVDs
iii. Hard drive is the most common
• Physical motor that spins the magnetic disks that store information
• Measured in Terabytes (billions of bytes)
iv. Flash drive
• USB sticks and SD cards
• No moving parts, have less power than hard drives
• Lower capacities and more expensive than hard drives
c. Differences between primary memory and secondary storage
i. Capacity
• Primary storage (a few gigabytes) is smaller than secondary storage (terabytes)
ii. Speed
• Primary memory is significantly faster than secondary storage
iii. Connectivity
• CPU can communicate directly with primary memory but not secondary storage
iv. Permanency
3. Peripherals
a. Every piece of hardware and physical device other than the CPU, primary memory and
secondary storage
b. May or may not be able to interact with some of them, such as a keyboard or Graphics
Processing Unit (GPU)
c. A driver allows the hardware to communicate with the operating system
i. Piece of hardware waits for an event to occur by an input device
ii. Puts information into the primary memory
iii. Hardware wakes up the CPU
iv. Operating system stops what it's doing (interruption) and uses the driver to interpret
the information
d. Alternative to event-based peripherals are polling peripherals, such as a camera
i. Operating system wants information from the peripheral and tells it to "wake up" and
gather the information
ii. Consume less power
Hardware Convergence
• Hardware (computer chips) for several hardware components are combined together into a single
chip
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
A computer is an interface where the mind and body can connect with the universe and move bits of it about. Hardware components: central processing unit (cpu, basic operations. Control flow (what to do next: a lot can be accomplished with these operations at a very fast pace, each cpu has its own machine language used to give it instructions. Instructions for one cpu typically do not work on another: similar to engine of a car. Some may consider colour, size, and features: characteristics of the cpu, model and make, will determine characteristics of the cpu. Speed: measured in gigahertz (ghz, billions of operations per second. Number of cores: usually has several processors or cores. Power consumption: number of cores affect power consumption. Some processors can slow down or switch to a "low battery mode" Information on secondary memory must be copied onto the primary memory before it can be used.
