Systems Architecture Flashcards
(24 cards)
Define sound
A vibration in a medium/a pressure wave in air
How do speakers replicate sound?
They receive electronic signals which cause surfaces/cones to move back and forth thus compressing air and creating pressure waves that propagate through the air outside the speaker
What are the characteristics of a pure tone
Single frequency, sinusoidal shape, no harmonics
How do we represent a sound wave digitally?
Take samples of the sound at regular intervals (sampling rate) that can be combined to form a digital representation of the sound wave
What happens when we decrease sampling rate?
Decrease in quality and decrease in file size
What happens as the number of samples tends to infinity?
We have a perfect representation of the sound wave
Define bit depth
The number of bits used to represent each sample of audio
What happens as we increase bit depth
Quality and file size increase
Storage = ?
Sample rate * bit depth * time * number of channels
Define sampling rate
Number of samples per second
Define bit depth
Number of bits used to represent each sample
Define number of channels
Number of audio channels .e.g. 1 for mono and 2 for stereo
Bits -> MBs?
/8000000
Why were sound cards developed?
The demand for complex audio increased
What do audio cards consist of?
- Amplifiers
- Input and output
- Multiple channels of sound
- Dedicated chips for processing sound and mixing channels
- MIDI support
- CD drive support
- Sometimes joystick ports
What is the key role of the kernel?
The management of hardware devices and the programs that are running on the system
How does the kernel enable each program to run as if it is the only process on the system?
It uses multi-tasking, preventing direct access and arbitrating device access between process
T/F: program code can change kernel data and access it
False, program code can’t change kernel data or code to allow it access
What are system calls?
Requests sent from programs to the kernel
Why do we need system calls?
It allows communication between user programs and the OS so there is an interface for requesting OS services
Define system call
A controlled entry point into the kernel that allows user-mode operations to request privileged operations
What happens if a system call takes too long?
The process is marked as unrunnable
