Files are not the only way to organize and store information. Databases are a common alternative.

Question 3 options:

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Streams are sequences of bytes without separate metadata and without a specific sequence length.

Question 4 options:

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Executable computer programs are composed of data (information) and instructions/code (also information) understood by computer hardware.

Question 5 options:

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A machine instruction tells computer hardware to perform some simple operation on some data and therefore cannot be stored in memory.

Question 6 options:

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Hardware reads an instruction from memory, performs the specified operation on the specified data, and then reads another instruction from memory. Instructions are always read from consecutive memory locations.

Question 7 options:

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The Von Neumann hardware architecture consists in part of a Processing Unit [often called Central Processing Unit (CPU)] containing an Arithmetic Logic Unit (ALU), processor registers including a Program Counter and a Control Unit and a memory to store both data and instructions.

Question 8 options:

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Instructions are numbers that are decoded by a processor.

Question 9 options:

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Assembly Language is human readable text that typically has a 1::1 correspondence with machine code.

Question 10 options:

	True
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Programs are typically loaded from files in persistent memory into slower volatile memory prior to execution by hardware.

Question 11 options:

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Applications use services/features provided by operating systems and exposed through Application Programming Interfaces (APIs).

Question 12 options:

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An operating system context switch is an operation that pauses execution of a thread of instructions in order to begin execution of a different thread of instructions. The frequency of context switches between applications and the operating system impacts aggregate system performance in ways interrupts do not.

Question 13 options:

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A "thread" is a sequence of instructions to be executed by a processor.

Question 14 options:

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BIOS and EFI are not examples of firmware.

Question 15 options:

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A process is a running (or ready to run if conditions are met) instance of a computer program.

Question 16 options:

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A process is an operating system data structure that stores information about a running program.

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In most modern operating systems, processes are subdivided into one or more threads of execution. Computers with more than one processor or processor cores can execute more than one thread at a time.

Question 18 options:

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Processes store information about security and permissions.

Question 19 options:

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Operating systems can halt processes and resume them later.

Question 20 options:

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OS Definition by Functionality

From Silbershatz: typical functionality includes

(i) To provide an environment for a computer user to execute programs on computer hardware in a convenient and efficient manner.

(ii) To allocate the separate resources of the computer as needed to solve the problem given. The allocation process should be as fair and efficient as possible.

(iii) As a control program it serves two major functions: (a) supervision of the execution of user programs to prevent errors and improper use of the computer, and (b) management of the operation and control of I/O devices."

Question 21 options:

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OS as a Collection of Components - All the instructions/code that constitutes an operating system can be organized into the following components: OS = VM + FileM + ProcM + Net + IO + UserM + (Boot) + [SysPrg] The components can also be combined and then re-divided into a kernel + initial ram disk components + drivers + interrupt handlers.

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OS as a Collection of System Calls - Linux and Windows have around 350 system calls each. From a programmers perspective, an operating system can be defined by its supported system calls.

Question 23 options:

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A "shell" in computing is an interface between the user and the operating system. Shells provide a way for users to select and execute other programs: A Shell is a program used to start other programs. The term shell usually refers to a Command-Line Interface (CLI), but Graphical User Interface (GUI) based shells are common. The Windows Desktop and Start button comprise a shell.

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Many Unix shells exist to meet different needs and personal preferences.

Question 25 options:

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An interpreter is a program that reads and executes other programs.

Question 26 options:

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Computer hardware only executes its own native machine instructions Humans find it tedious, error prone, and unproductive to write machine instructions directly (but we can). High level programming languages exist to simplify programming. High level programming languages must be converted into native machine instruction to execute.

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A compiler translates high level language inputs into machine instructions and typically stores the machine instructions in a file for later execution.

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An interpreter translates high level language inputs into machine instructions and typically executes them immediately.

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Unix shells are interpreters.

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Various Unix shells interpret slightly different languages.

Question 31 options:

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Most shell scripting languages enable programmers to write loops.

Question 32 options:

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Java is a hybrid of Compiler and Interpreter. Java compiles high level language statements into standard byte code. Byte codes are like machine instructions for a virtual machine virtual means not real. The Java Virtual Machine (JVM) translates byte codes into native machine code on the fly just in time and then executes the native machine code. Just in Time (JIT) compiling produces faster program execution than traditional interpretation in many cases.

Question 33 options:

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The Unix philosophy, originated by Ken Thompson, is a set of cultural norms and philosophical approaches to minimalist, modular software development. Unix programs have always been expected to follow the concept of DOTADIW, or "Do One Thing and Do It Well."

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A File System defines how information is stored and retrieved. Filesystems separate collections of related information into "files".

Question 35 options:

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File systems manage access to both the content of files (data) and information about files (metadata).

Question 36 options:

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File systems arrange storage space. Reliability, efficiency, and physical storage medium limitations influence file system design.

Question 37 options:

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There are many different kinds of file systems. Each has a different structure and logic with different properties of speed, flexibility, security, size, fragmentation and more. For example the ISO 9660 file system is designed specifically for magnetic tape.

Question 38 options:

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File systems can be used on many different kinds of storage devices. Some examples include spinning magnetic media, spinning optical media, magnetic tape, paper tape, film, volatile memory, and Network Attached Storage (NAS).

Question 39 options:

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File systems can operate over networks with file storage connected to computers at different locations than the computer accessing the data in files. Examples include Network File System (NFS) - developed by Sun Microsystems in 1984, Server Message Block (SMB) a.k.a. Common Internet File System (CIFS) developed by IBM and Microsoft 1990-1992.

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File systems organize bytes. Bytes can be stored in files. It is therefore impossible to implement an entire file system within a single file stored by a different file system.

Question 41 options:

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A RAM disk/drive is a block of RAM (Random Access Memory - volatile memory) containing data organized by a file system. One upon a time, this approach improved performance for temporary file system operations such as creating intermediate files while compiling. Modern virtual memory systems do a better job. A RAM disk in a modern system is usually a pointless extra layer of protocols above virtual memory.

Question 42 options:

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