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The range of numbers thatn-bit binary number can present if interpreted as a signed or an unsigned integer is helpful to you when you write a program because if you know the values that a variable in your program may take, you can make a precise decision about the type of that variable when you declare it. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
An x86-64 Intel processor uses a complex instruction set computer architecture (CISC). This type of architecture combines many simple instructions into a simple complex one. Other processor architectures use a reduced instruction set architecture (RISC) based on simpler instructions. RISC V is a relatively new RISC ISA... | https://openstax.org/books/introduction-computer-science/pages/5-summary |
Assembly language makes use of processor instructions that are part of the instruction set architecture (ISA) of the processor being used. These instructions can be converted to binary code, referred to as machine language code, using an assembler. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
Assembly language provides specific instruction to perform common operations such as addition and multiplication of signed and unsigned integers. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
We must use different technologies to build a near ideal memory because each technology has some good characteristics and a few shortcomings. Therefore, we use multiple technologies to get the best of all. Various types of memory, such as DRAM and SRAM, are available and differ in access speed and associated costs. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
Those technologies are organized as a hierarchy. Technologies that are fast but expensive are at the top of the hierarchy, but their storage capacity is not big. As we go down the hierarchy, the technology is slower, but cheaper; hence, we use a lot of storage from it. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
That is, characteristics of each technology determine its place in the hierarchy. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
By paying attention to locality in accessing the data, the programmer can get the best performance from the hierarchy. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
Processors evolved from a single cycle implementation to multicore. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
The norm now is to have a multicore processor working in tandem with one or more accelerator chips. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
The norm in software development is to write parallel code for such a heterogeneous system. Sequential programming will soon be dated. | https://openstax.org/books/introduction-computer-science/pages/5-summary |
access control list (ACL) : list of rules that specifies which users are granted the access to a specific object or resource | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
access enforcement : part of the OS that is responsible for enforcing access controls and protecting authentication and authorization information | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
address space : set of addresses generated by programs as they reference instructions and data | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
address translation : stage of virtualization that occurs when the system needs to find a physical address in the memory that matches the virtual address | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
allocation : method that defines how data is stored in the memory by providing a set of requests for resources and identifying which processes should be given which resources to make the most efficient use of the resources | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
application programming interface (API) : set of rules and tools that allows different software applications to communicate with each other | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
authentication : process of checking to see if a userâs credentials match the credentials in a database of authorized users or in a data authentication server | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
authorization : process of determining the relationship between principals, operations, and objects by defining which principals can perform which operations on which objects | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
badge : logical access system that serves as a form of authentication | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
blocked state : when a process is waiting for an event to occur | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
cache-only memory architecture (COMA) : computer memory architecture where all memory is treated as cache, which allows for the dynamic allocation of data for optimized access and performance in multiprocessor environments | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
capability list : list of objects and operations for each user that defines the user rights and capabilities | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
cloud infrastructure : virtualized and scalable hardware resources delivered over the Internet as a service | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
concurrency : multiple activities and processes happening at the same timeâin other words, the OS handling multiple tasks at once | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
concurrent processing : computing model that improves the performance when multiple processors execute instructions simultaneously | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
condition variable : synchronization mechanism that is used in conjunction with locks to allow threads to wait for certain conditions to become true | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
container : standardized unit of software that logically isolates an application enabling it to run independently of physical resources | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
context switch : procedure that a computerâs CPU follows to change from one task to another while ensuring that the tasks do not conflict | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
CPU state : consists of the program counter (PC), the stack pointer (SP), and general-purpose registers | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
critical section : piece of code that only one thread can execute at once; also, only one thread at a time will get into this section of code | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
deadlock : synchronization challenge that occurs when a set of threads are blocked forever, waiting for each other to release resources | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
demand paging : storage mechanism in which pages should only allocate in the memory if it is required from the execution process | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
device manager : layer in the layered OS architecture that handles devices and provides buffering | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
device register : interface view any device presents to a programmer where each I/O device appears in the physical address space of the machine as a few words | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
directory : set of files that contains all the required information about the files such as attributes, location, and ownership, which is managed by the OS | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
distributed file system (DFS) : file system that is distributed on multiple file servers or multiple locations that support network-wide sharing of files and devices | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
dual mode : OS structure that is responsible for separating the user mode from the system mode | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
dynamic linking : code is located and loaded when the program is first run | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
encryption : method that converts the data into secret code that hides the dataâs true meaning | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
exception : error that occurs at runtime | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
exokernel : OS architecture that simplifies the operating system by making its core (kernel) really small and letting apps have more control over the computerâs hardware | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
fault containment : feature of an OS that prevents errors in one part of an application from affecting the whole system | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
fault recovery : feature of an OS that helps the system to fix itself or revert to a previous state after an error | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
fault tolerance : feature of an OS that allows the application to keep running even when errors occur | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
file : collection of related information that is stored on secondary/virtual storage; itâs the smallest storage unit from the userâs perspective | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
file system : responsible for defining file names, storing files to a storage device, and retrieving files from storage devices | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
file versioning : system that allows a file to exist in several versions at the same time, which gives the user complete control over file creation | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
first come, first served (FCFS) : scheduling algorithm that operates on a simple queue mechanism where the first process to request the CPU is the first to receive it (or the first element added to the queue is the first one to be removed); commonly used in resource scheduling and data buffering and also known as FIFO ... | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
fragmentation : problem where the memory blocks cannot be allocated to the processes due to their small size and the blocks remain unused | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
frame buffer : portion of random access memory (RAM) containing a bitmap that drives a video display | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
full virtualization : memory virtualization approach that allows multiple operating systems to run concurrently on a single physical machine, fully isolated from each other, by emulating hardware resources through a hypervisor | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
general-purpose register (GPR) : extra register that is used for storing operands and pointers | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
graphical user interface (GUI) : visual interface that allows users to interact with electronic devices through graphical icons and visual indicators | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
guest modification : in the context of virtualization, altering the guest operating system or its configuration to improve compatibility, performance, or integration with the virtualization environment or hypervisor | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
guest operating system : complete operating system inside a virtual machine | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
hardware abstraction layer (HAL) : example of layering in modern OS that allows an OS to interact with a hardware device at a general or abstract level rather than going deep into a detailed hardware level; this improves readability | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
heap allocation : dynamic storage management approach that allocates the data in a tree-based data structure | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
heap data : tree-based data in process management | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
hypervisor : software layer between machine hardware and the operating systems that run on it | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
i-number : unique number given to an inode whenever an OS that uses inodes creates a new file, which, in effect, functions as the fileâs name | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
inconsistency : situation that causes the system to produce errors or hardware failure | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
incremental backup : backup image containing the pages that have been updated from the time of the previous backup | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
inode : structure used by file system that contains metadata about a file or directory but not its name | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
inter-process communication (IPC) : mechanism that enables processes to exchange data among different processes running on an operating system | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
interrupt : signal to the processor from either software or hardware that indicate events that need immediate attention | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
isolation : ensures that the multiple programs that are running concurrently on the same CPU and memory operate independently without interfering with each otherâs execution or data | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
layered OS architecture : OS architecture where the OS is implemented as a set of layers where each layer exposes an enhanced virtual machine to the layer above | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
lock : synchronization mechanism that is used to enforce mutual exclusion | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
mechanism : activities that enforce policies and often depend on the hardware on which the operating system runs | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
memory allocation : process of setting aside sections of memory in a program to be used to store variables and instances of structures and classes | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
memory deallocation : process of freeing the space corresponding to finished processes when that space is needed by the rest of the system | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
memory multiplexing : dividing the capacity of the communication channel into multiple logical channels | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
microkernel : OS architecture where the functionality and capabilities are added to a minimal core OS as plug-ins | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
monolithic design : OS architecture where the entire OS is working in kernel space | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
multitasking : approach toward achieving concurrency that makes it possible for the OS to run multiple processes at the same time using time slicing | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
mutual exclusion : program that prevents simultaneous access to a shared resource | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
non-privileged system program : program that can run only in the user mode | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
non-uniform memory access (NUMA) : computer memory architecture where memory access time varies depending on the memoryâs location relative to a processor | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
operating system (OS) : core piece of software that typically manages the interconnection of hardware and software on a given computer | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
page fault : when the CPU demands a page, and this page is not present in the main memory | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
page fetching : process of bringing pages into memory | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
page manager : layer in the layered OS architecture that implements virtual memories for each process | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
page replacement : when one page in the DRAM is swapped to disk while the requested page is brought into DRAM | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
paging : storage mechanism that uses a page form in retrieving process from secondary or virtual memory to main memory | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
pipe : data communication method between two processes that uses a specific name and standard I/O operations, and thus allows for data transfer within a file system; sometimes called named pipe | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
policy : controls how to use a mechanism in specific situations, that is, choose what activities need to be done | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
primary memory : type of computer memory that is the initial point of access for a processor and serves as direct storage for the CPU | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
primary storage : holds data that can be directly accessed by the CPU with minimum or no delay and does not survive a power failure | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
privileged instruction : instruction provided by the CPU that can be executed only by the OS | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
privileged system program : program that can run only in the system mode | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
process : any program that is running on top of the OS | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
process control block (PCB) : data structure used by the operating system to store information about a process, including its state, process ID, registers, scheduling information, memory management details, and I/O status | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
process ID (PID) : unique identifier assigned by the operating system to each process running on a computer, used to track and manage process activities | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
process synchronization : when an OS manages the sharing of a systemâs resources to avoid interference and errors | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
properties : characteristics that are considered when designing an OS | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
protection : general mechanism that is used throughout the OS for all resources that need to be protected, such as memory, processes, files, devices, CPU time, and network bandwidth | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
quota : amount of space to store files based on the available memory space | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
ready state : when a process is waiting for the CPU | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
recovery : process of resolving or receiving treatment to solve OS faults or errors | https://openstax.org/books/introduction-computer-science/pages/6-key-terms |
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