chapter 1 heehoo systems architecture memory n storage Flashcards
Def. hardware
any physical component that makes up the computer
def. software and firmware)
software - any program that runs on the computer
firmware - software that comes predownloaded and cannot be deleted
purpose of CPU
- performs the FDE cycle
- manages the rest of the hardware
what is the CPU made up of?
main memory (RAM), the processor(s), cache memory
purpose of address bus
carries addresses from the processor to memory and input/output devices
purpose of data bus
sends data between the processor, memory and input/output devices
purpose of control bus
carries signals to coordinate all the computer activities
purpose of control unit (4 points)
- controls the execution of instructions in the correct order
- decodes instructions
- regulates and controls processor timing using regular pulses from the system clock
- sends and receives control signals to and from other devices within the computer
functions of ALU
- logical operations ( and, or, not)
- shift operations (binary shift)
- arithmetic operations
MAR purpose
holds the address of the instruction/piece of data to be fetched or stored
MDR purpose
where the data/program instruction is temporarily held after being fetched from memory
program counter purpose
holds the memory address of the next instruction to be processed
increments every time the FDE cycle is carried out
CIR purpose
holds the current instruction to be executed, which has been fetched from memory and is temporarily held in the MDR before being copied to the CIR
accumulator purpose
a general purpose register where all calculations are carried out
what is clock speed? units?
the number of instructions/data processed per second
hertz
define cache memory
the small amount of very fast memory where frequently used instructions and data can be stored temporarily
what is an embedded system?
a computer system that has a dedicated function as a part of a larger device
5 examples of embedded systems
microwave dishwasher dvd player MP3 car engine management systems
factors affecting CPU performance
clock speed
number of cores
amount of cache memory
amount of ram
3 advantages of embedded systems
- low power devices so they can operate effectively from a small power source
- small in size to fit inside a wrist worn device (e.g. a fitness bracelet)
- rugged so they can be used in a wide range of appliances e.g. car engine management systems
- low cost making them suitable for mass produced products
- dedicated to just one task with dedicated interfaces and software
define volatile
needs power to be maintained - if the power is turned off, RAM loses its contents
what is stored in RAM?
- loaded operating system
- any instructions, data or programs currently being executed/in use
difference between DRAM and SRAM
DRAM is cheaper and stores more
SRAM is faster
ROM- volatile? contents?
not volatile
BIOS/bootstrap loader (small program that loads the OS)
features to consider when choosing a secondary storage medium
capacity speed reliability durability cost portability
pros of magnetic disk drives (HDD)
pros
- massive fuckin capacity
- low cost per GB
pros of solid state drives
pros
- less susceptible to shock and damage because there are no moving parts
- lighter - more suitable for portable device
- faster access time than HDDs
- lower power consumption than HDDs
- run much cooler than HDDs
- thin because no moving parts
pros of cloud storage
pros
- you can access data from anywhere with an internet connection
- you can share data with people in different locations
- backup isn’t an issue as it is the responsibility of the provider to keep the data safe
- automatic updates
what is virtual memory
memory management procedure needed when RAM is full
the OS creates a temporary section of volatile memory that acts as RAM in secondary storage
data currently not in us is sent here
cons of cloud storage
cons
- you can’t access your data without an internet connection
- some users are concerned about security in the cloud and whether their data could be accessed by a hacker
cons of magnetic disk drives (HDD)
cons
-moving parts so
• slow to read from/write to
• more susceptible to damage
- vulnerable to magnetic fieldscons of solid state drives
cons
- more expensive per GB
- less dense
