COMPUTERS Flashcards
Operand
In mathematics an operand is the object of a mathematical operation, i.e., it is the object or quantity that is operated on.
The following arithmetic expression shows an example of operators and operands:
3
+
6
=
9
{\displaystyle 3+6=9}
In the above example, ‘+’ is the symbol for the operation called addition.
The operand ‘3’ is one of the inputs (quantities) followed by the addition operator, and the operand ‘6’ is the other input necessary for the operation.
The result of the operation is 9. (The number ‘9’ is also called the sum of the augend 3 and the addend 6.)
An operand, then, is also referred to as “one of the inputs (quantities) for an operation”.
https://en.wikipedia.org/wiki/Operand
Operator
In mathematics, an operator is generally a mapping or function that acts on elements of a space to produce elements of another space (possibly the same space, sometimes required to be the same space). There is no general definition of an operator, but the term is often used in place of function when the domain is a set of functions or other structured objects.
Examples of operators: \+ addition = equals - minus / division
https://en.wikipedia.org/wiki/Operator_(mathematics)
Instruction Set Architecture (ISA)
In computer science, an instruction set architecture (ISA) is an abstract model of a computer.
It is also referred to as architecture or computer architecture.
A realization of an ISA, such as a central processing unit (CPU), is called an implementation.
In general, an ISA defines the supported data types, the registers, the hardware support for managing main memory, fundamental features (such as the memory consistency, addressing modes, virtual memory), and the input/output model of a family of implementations of the ISA.
An ISA specifies the behavior of machine code running on implementations of that ISA in a fashion that does not depend on the characteristics of that implementation, providing binary compatibility between implementations. This enables multiple implementations of an ISA that differ in performance, physical size, and monetary cost (among other things), but that are capable of running the same machine code, so that a lower-performance, lower-cost machine can be replaced with a higher-cost, higher-performance machine without having to replace software. It also enables the evolution of the microarchitectures of the implementations of that ISA, so that a newer, higher-performance implementation of an ISA can run software that runs on previous generations of implementations.
https://en.wikipedia.org/wiki/Instruction_set_architecture#Instructions
Data Type
In computer science and computer programming, a data type or simply type is an attribute of data which tells the compiler or interpreter how the programmer intends to use the data. Most programming languages support basic data types of integer numbers (of varying sizes), floating-point numbers (which approximate real numbers), characters and Booleans. A data type constrains the values that an expression, such as a variable or a function, might take. This data type defines the operations that can be done on the data, the meaning of the data, and the way values of that type can be stored. A data type provides a set of values from which an expression (i.e. variable, function, etc.) may take its values.
Common data types include: Integer. Floating-point number. Character. String. Boolean.
https://en.wikipedia.org/wiki/Data_type
Central Processing Unit (CPU)
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and input/output (I/O) operations specified by the instructions in the program. This contrasts with external components such as main memory and I/O circuitry,[1] and specialized processors such as graphics processing units (GPUs).
https://en.wikipedia.org/wiki/Central_processing_unit
I / O = Input — Output
In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals or data received by the system and outputs are the signals or data sent from it. The term can also be used as part of an action; to “perform I/O” is to perform an input or output operation.
I/O devices are the pieces of hardware used by a human (or other system) to communicate with a computer. For instance, a keyboard or computer mouse is an input device for a computer, while monitors and printers are output devices. Devices for communication between computers, such as modems and network cards, typically perform both input and output operations.
https://en.wikipedia.org/wiki/Input/output
Memory-mapped I/O (MMIO)
Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer. An alternative approach is using dedicated I/O processors, commonly known as channels on mainframe computers, which execute their own instructions.
Memory-mapped I/O uses the same address space to address both memory and I/O devices. The memory and registers of the I/O devices are mapped to (associated with) address values. So when an address is accessed by the CPU, it may refer to a portion of physical RAM, or it can instead refer to memory of the I/O device. Thus, the CPU instructions used to access the memory can also be used for accessing devices. Each I/O device monitors the CPU’s address bus and responds to any CPU access of an address assigned to that device, connecting the data bus to the desired device’s hardware register.
https://en.wikipedia.org/wiki/Memory-mapped_I/O
Channel I/O
In computing, channel I/O is a high-performance input/output (I/O) architecture that is implemented in various forms on a number of computer architectures, especially on mainframe computers. In the past, channels were generally[a] implemented with custom devices, variously named channel, I/O processor, I/O controller, or DMA controller.
Many I/O tasks can be complex and require logic to be applied to the data to convert formats and other similar duties. In these situations, the simplest solution is to ask the CPU to handle the logic, but because I/O devices are relatively slow, a CPU could waste time (in computer perspective) waiting for the data from the device. This situation is called ‘I/O bound’.
Channel architecture avoids this problem by using a logically independent, low-cost facility. Channel processors are simple, but self-contained, with minimal logic and sufficient scratchpad memory (working storage) to handle I/O tasks. They are typically not powerful or flexible enough to be used as a computer on their own and can be construed as a form of coprocessor. On some systems the channels use memory or registers addressable by the central processor as their scratchpad memory, while on other systems it is present in the channel hardware.
A CPU designates a block of storage or sends a relatively small channel programs to the channel in order to handle I/O tasks, which the channel and controller can, in many cases, complete without further intervention from the CPU (exception: those channel programs which utilize ‘program controlled interrupts’, PCIs, to facilitate program loading, demand paging and other essential system tasks).
https://en.wikipedia.org/wiki/Channel_I/O
Direct Access Memory (DMA)
Direct memory access (DMA) is a feature of computer systems that allows certain hardware subsystems to access main system memory (random-access memory) independent of the central processing unit (CPU).
Without DMA, when the CPU is using programmed input/output, it is typically fully occupied for the entire duration of the read or write operation, and is thus unavailable to perform other work. With DMA, the CPU first initiates the transfer, then it does other operations while the transfer is in progress, and it finally receives an interrupt from the DMA controller (DMAC) when the operation is done. This feature is useful at any time that the CPU cannot keep up with the rate of data transfer, or when the CPU needs to perform work while waiting for a relatively slow I/O data transfer. Many hardware systems use DMA, including disk drive controllers, graphics cards, network cards and sound cards.
https://en.wikipedia.org/wiki/Direct_memory_access
Random-access memory (RAM)
Random-access memory (RAM /ræm/) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code.[1][2] A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory. In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.
RAM contains multiplexing and demultiplexing circuitry, to connect the data lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, and RAM devices often have multiple data lines and are said to be “8-bit” or “16-bit”, etc. devices.
https://en.wikipedia.org/wiki/Random-access_memory
Read-only memory (ROM)
Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing software that is rarely changed during the life of the system, also known as firmware. Software applications (like video games) for programmable devices can be distributed as plug-in cartridges containing ROM.
https://en.wikipedia.org/wiki/Read-only_memory
Diode matrix
A diode matrix is a two-dimensional grid of wires: each “intersection” wherein one row crosses over another has either a diode connecting them, or the wires are isolated from each other.
It is one of the most popular techniques[citation needed] for implementing a read-only memory. A diode matrix is used as the control store or microprogram in many early computers. A logically equivalent transistor matrix is still used as the control store or microprogram or ‘decode ROM’ in many modern microprocessors.
At any one instant, a single row of the diode matrix (or transistor matrix) is activated. Charge flows through each diode connected to that row. That activates the column corresponding to each row. The only activated control signals during that instant were those whose corresponding column wire was connected with a diode to that row.
https://en.wikipedia.org/wiki/Diode_matrix
Diode logic (DL)
Diode logic (DL), or diode-resistor logic (DRL), is the construction of Boolean logic gates from diodes. Diode logic was used extensively in the construction of early computers, where semiconductor diodes could replace bulky and costly active vacuum tube elements. The most common use for diode logic is in diode–transistor logic (DTL) integrated circuits that, in addition to diodes, include inverter logic to provide a NOT function and signal restoration. While diode logic has the advantage of simplicity, the lack of an amplifying stage in each gate limits its application. Not all logical functions can be implemented in diode logic alone; only the non-inverting logical AND and logical OR functions can be realized by diode gates. If several diode logic gates are cascaded, the voltage levels at each stage are significantly changed, so diode logic is normally limited to a single stage, though, in special designs, two-stage systems are sometimes achieved.
https://en.wikipedia.org/wiki/Diode_logic
AI (Artificial Intelligence)
https://en.wikipedia.org/wiki/Glossary_of_artificial_intelligence
