Computer Systems Flashcards
What is software?
Programs that the computer system runs
What is hardware?
The physical components that make up the computer
What is the function of system software?
system software manages the computer system resources and acts as a platform to run application software
What is the function of the application software?
application software is software that performs end-user tasks
What is the function of the operating system?
A collection of programs that manage and control the computer. Connects the hardware with the software
What are the main roles of the OS?
- oranising the CPU and it’s processing tasks
- memory managment and allocation
- communicating with input/output (I/O) devices
- providing a platform for applications to run on
- managing security security and user accounts
Describe what a processing manager does?
It allocates the times each program has with the CPU, it allows multi tasking
Describe what a memory manager does?
Paging - allocation of memory, what goes in the RAM or secondary storage
Describe what a device driver does?
Allows instructions to be exchanged within peripherals (input output devices) , the have different languages.
Describe what a security manager does?
Individual users can be created and deleted,
Access levels to users
Passwords and usernames
What is the function of the utility systems?
Helps to maintain the systems
Utility programs help maintain or configure a computer
What does the utility system software include?
🟣encryption (security) 🟣defragmentation 🟣virus scanner 🟣back ups 🟣compression
Describe defragmentation
Takes fragmented files in the hard drives and puts them together, so that when the file is needed time won’t be wasted finding it. (Decreases time read/write head spends moving back and forth across the disk))
Describe the function of back ups
Made to high capacity secondary storage devices or the cloud, in case data is lost to hacker
Describe the control unit
It fetches , decides and executes instructions
Controls hardware and moves data around the computer
Describe the ALU
The arithmetic logic unit does arithmetic and logical calculations
Describe the registers
Small amounts of High speed memory contained within the CPU. PC MAR MDR CIR
Cache
Small amount of high speed RAM. Temporarily holds data and instructions that the processor is likely to reuse
Clock
Co- ordinates all of the computer components by sending out regular electrical pulses which synchronises all the components.
The frequency is known as the clock speed
What is the Von Neuman Architecture?
Data and instructions are stored together and have memory addresses
How does clock speed affect CPU performance
The more pulses per second , the more FED cycles can be performed. This could lead to over heating tho
How does cache size affects CPU performance?
The larger the chance is , the less time a processor has to wait for instructions to be fetched
How does the number of cores affect the CPU performance?
Then more instructions can process in a given space of time, but some instructions rely on the previous so is not proportional to speed.
The fetch decode execute cycle
🟣the CU reads the memory address of the next instruction
🟣this instruction is copied to the registers
🟣the address is incremented by 1
🟣the instruction is decoded by the CU
🟣the instruction is performed
Eg: ALU performing a calculation, data being stored into memory
Embedded system
Dedicated systems within a larger system
Only have ROM,
Cheaper
Less power required- batteries
What is a computer system.
The software and hardware of a computer
what is a high level language?
a language easier for humans to understand .
Therefore, requires translation into machine code , by compiler, translator or assembler
*high level code = source code
eg: python / java
what are low level languages?
closely represents machine language
difficult to understand , but execute faster
eg: machine code , assembley language
Pros and cons of high and low level languages
*low language is efficient use of hardware available
what is a translator?
something that translates the source code into machine code
= interpreter or compiler
something that translates assembly langue into machine code
=assembler
What is a compiler?
takes the source code and translates it into machine code all in on go
What is an interpreter?
translates source code into machine code, one instruction at a time.
when error is found , the translation process will stop and the location of error is highlighted
What is an assembler?
translates assembly language into machine code
Compiler pros and cons
✅programs run quickly , as have already been translated
✅only needed once to create an executable file , which is then portable
❌source code must be re-compiled every time the programmer changes the
program
❌code must be completely error free to compile
Interpreter pros and cons
✅once an error is found , the program is stopped, debugging is easier
✅✅
❌no executable file is made , so an interpreter is needed each time the program want to be run
❌program run more slowly , as code is being translated ❌
Low Level languages pros and cons
LL ✅= more control over program , program can be made with less memory use (more efficient)
Greater control over CPU, program may bee needed to run quicker
Maintain old code / hardware
❌=
Harder to read and learn ,
Only works for one type of machine and architecture
High levels pros and cons
✅ easier to learn read and write , debugging i is easier ,
Can be translated into multiple machine architectures
❌ not much control over the CPU so the program may be slower ,
Not much control over the program , program may have a higher memory memory use
Will need to be translated by an interpreter or a compiler
What are embedded systems?
computers system built into other devices
what are some advantages of embedded systems ?
✅Use ROM instead of RAM for main memory , which is cheaper
✅more reliable, require less maintamce and lasts longer
Why might assembler language be used ?
More readable than machine code, Easter to write and edit programs
assembly language has a 1:1 correspondence with machine code
what is the Von Neumann architecture?
a type of CPU architecture , where only one memory is used for both the data and instructions.
The CPU runs programs stored in mmory , programs consist
What is the difference between secondary and primary memory ?
Primary: CPU has direct access to (registers, cache, ROM & RAM)
Volatile ( only on with power)
Fast read/write speed
Secondary: not directly accessible
Non-volatile
Where data is stored when not in use
Slow read/ write speed
Magnetic Hard Disks
Made up of magnetised metal disks spinning .
1 &0 for magnetised and demagnetised
Data is stored in sectors , on tracks.
Read write head on a movable arm accesses these sectors.
Long lasting( but moving parts), cheap, large capacity
Solid state (flash)
Drive: Data stored in electrical circuits, by tapping electrons. (Transistors) Fast read write time. Don’t need defragmentation More long lasting, no heat no moving parts, Silent
Optical discs
Eg: CD, DVD, blue Ray
Pits/ (0)holes are made, the reflected beam from laser read is the data
Low capacity, cheap, portable , slow read/write
What is Cloud storage
Data is uploaded via the internet to a remote server (stored on HDD/SSD) . You pay with a subscription.
Roles of the OS
Communicating with input output devices/ via device driver
Process manager- CPU and it’s time with programs
Providing a platform for applications to run
Memory management- how much RAM a program has access to
File management-read/write/delete
System management- user passwords
Why is secondary storage required?
To store long term
Retains data when no power (non-volatile)
High capacity
What is durability?
How much physical damage it can take without breaking
Put in order , in terms of how quickly data is transferred (speed)
Solid
Magnetic
Optical
What are the shapes for AND, OR,NOT and XOR
And- D
Not-triangle &circle
Or- arrow head
XOR- arrowhead with line, does not accept two trues
How do you calculate the total number of combinations for a truth table?
2 * * number of inputs
Eg:
2* * 3 =8
2**2= 4
Symbols for NOT, OR, AND, NOT OR
Not= line overhead
And = .
Or= +
Not or = circle over +
What are advantages and disadvantages of cloud storage?
:)can be accessed from anywhere,
data can be shared ,
cheap,
provides back up/security
:( need Wi-Fi,
data vulnerable to hackers,
Why choose a high level language?
🟡High level have built in subroutines
🟡Provides programming structures such as iteration and selection
🟡Easier to debug
🟡Easier to understand (more easier to read)
what are some examples of application software?
- games
- web browsers
- word processors
- database software
what are some examples for system software?
- operating system
- utilities
