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COP4610 Exam 1 with verified solutions graded A+
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COP4610 Exam 1 with verified solutions graded A+
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COP4610 Exam 1, COP4610, COP 4610Exam 1, COP4610
Operating system - correct answer ✔✔- Acts as an intermediary between the user and the computer
hardware.
- Software that manages the computer hardware.
- Purpose is to provide an environment in which a user can execute programs in a convenient and
efficient manner.
- A virtual machine that hides the complexity and limitation of hardware from application programmers
History Phase I: Expensive Hardware, Cheap Humans - correct answer ✔✔Hardware: mainframes
OS: human operators
- Handle one job (a unit of processing at a time.
- Computer time wasted while operators walk around the machine room.
Batch system - correct answer ✔✔Collects a batch of jobs before processing them and printing out
results.
- collection, processing, and printing out results can occur concurrently.
Job - correct answer ✔✔A unit of programming
Batch System - correct answer ✔✔Collects a batch of jobs before processing them and printing out
results
Timeshares - correct answer ✔✔Each user can afford to user terminals to interact with machines
OS Design goals: - correct answer ✔✔Efficient use of the hardware
More efficient use of human resources
,Allow a user to perform many tasks at one time
Ease of resource sharing between machines
Four phases of OS history - correct answer ✔✔Hardware expensive, humans cheap
Hardware cheap, humans expensive
Hardware very cheap, humans very expensive
Distributed systems
Multiprocessing - correct answer ✔✔The ability to use multiple processors on the same machine
Multitasking - correct answer ✔✔Ability to run multiple programs on the same machine
Multiprogramming - correct answer ✔✔Multiple programs can run concurrently
Benefits of concurrency - correct answer ✔✔Can run multiple programs simultaneously
Better resource utilization
Better average response time
Better performance
Thread - correct answer ✔✔A sequential execution stream
,Address space - correct answer ✔✔Contains all necessary states to run a program
Process - correct answer ✔✔An address space and at least one thread of execution
Difference between process and program - correct answer ✔✔A program is just a collection of
statements, a process is a running instance of a program.
Uniprogramming - correct answer ✔✔Running one process at a time
Multithreading - correct answer ✔✔having multiple threads per address space
Dispatching loop - correct answer ✔✔Run thread
Save States
Choose new thread
Load states from new thread
Context switch - correct answer ✔✔Switching the CPU from one thread/process to another
Thread state diagram - correct answer ✔✔Ready -> Running -> Blocked ->Ready etc.
Ready-> Running: Scheduled
Running-> Ready: yield, timer
Running -> Blocked: I/O request
Blocked -> Ready: IO complete
Amdahl's Law - correct answer ✔✔S = %of sequential computations
N = cores
x = 1/(S + (1-S/N))
, Booting sequence - correct answer ✔✔Jump
Load from BIOS
POST
Load MBR
Load OS loader
Load kernel image
sets kernel mode
Jump
System call - correct answer ✔✔Allows processes running in user mode to access kernel functions that
run under kernel mode
Kernel Mode - correct answer ✔✔Used for lowest level functions of operating system. Executing code
has unrestricted access to hardware
User mode - correct answer ✔✔Executing code has no way to directly access or modify hardware or
reference memory
Master Boot Record - correct answer ✔✔Information in the first sector of memory that identifies how
and where to boot the OS
System call sequence - correct answer ✔✔User level: Trap
Kernel Level: Set kernel mode
Branch table
Run trusted code
Process creation - correct answer ✔✔fork(): Clones the process
exec: overwrites current process
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