SCC131: weeks 19-24
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
what does Hz reference in sound sampling?
-how many times a sample is taken of the sound per second
what happens when the number of samples are increased/frequency is increased?
-more accurate sound -bigger file size
what is the bit depth?
-number of bits used to represent a sound value
what is the impact of increased bit depth?
-more accurate sound -bigger file size
what is the formula for file size?
file size in bits = sample rate (Hz) x bit depth x number of audio channels (mono = 1, stereo = 2) x duration
what is an operating system?
-manages hardware and software -controls components
what are the main tasks of an operating system?
-file management -memory management -process management -I/O handling -security: access and control -multitasking and scheduling
what are some example operating systems?
-windows -apple -unix -macOS -Blackberry -Android
what is the difference between a process and a thread?
-processes can have one or multiple threads -threads within a process share the same resources but execute independently
what are some properties of threads?
-lightweight: uses fewer system resources -shared memory and global variables -fast context switching: threads switch without memory mapping
how does the operating system control the execution of processes?
keeps track of: —executing code —memory and system resources belonging to processes —security permissions
what is the kernel?
-core of OS -a program at core of OS that has control over everything in the system
what are some common kernel designs?
-monolithic kernels -micro-kernels
what is a monolithic kernal?
single programs that contain all kernel functions. used in most devices
what is a micro-kernel?
areas of functionality split into multiple different programs
how does the kernel work?
-loaded into memory during computer setup. remains there until shut down -kernel mode/user mode: execution mode in OS to differentiate application level/system level operations
what is the difference between kernel mode and user mode?
-un/restricted access to computer resources -un/limited memory access -hardware access -mode switching
what does scheduling refer to?
-moving processes in and out of the CPU depending on which processes need to be executed -dictated by OS
why is scheduling important?
-utilizing CPU power efficiently and executing processes fairly, not neglecting certain processes
what are two types of multitasking?
-pre-emptive multi-tasking -cooperative multi-tasking
what is pre-emptive multi-tasking?
-memory determines an allocated time for each process to run -windows/linux/macOS
what is cooperative multi-tasking?
-tasks give up CPU control voluntarily, well behaved -older OSs
what are some scheduling algorithms used by the OS?
-first come, first served -shortest job next -round robin -priority scheduling -multi-level queue scheduling
what is the technique used to simulate multitasking from the OS?
-time slicing -processes are frequently switched in and out of the processor to simulate parallelism