Power-on Self-test
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Power-on Self-test
A power-on self-test (POST) is a process performed by firmware or software routines immediately after a computer or other digital electronic device is powered on. This article mainly deals with POSTs on personal computers, but many other embedded systems such as those in major appliances, avionics, communications, or medical equipment also have self-test routines which are automatically invoked at power-on. The results of the POST may be displayed on a panel that is part of the device, output to an external device, or stored for future retrieval by a diagnostic tool. Since a self-test might detect that the system's usual human-readable display is non-functional, an indicator lamp or a speaker may be provided to show error codes as a sequence of flashes or beeps. In addition to running tests, the POST process may also set the initial state of the device from firmware. In the case of a computer, the POST routines are part of a device's pre-boot sequence; if they complete succes ...
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POST P5KPL
Post or POST commonly refers to: *Mail, the postal system, especially in Commonwealth of Nations countries **An Post, the Irish national postal service **Canada Post, Canadian postal service **Deutsche Post, German postal service **Iraqi Post, Iraqi postal service **Russian Post, Russian postal service **Hotel post, a service formerly offered by remote Swiss hotels for the carriage of mail to the nearest official post office **United States Postal Service or USPS **Parcel post, a postal service for mail that is heavier than ordinary letters *Post, a job or occupation Post, POST, or posting may also refer to: Architecture and structures *Lamppost, a raised source of light on the edge of a road *Post (structural), timber framing *Post and lintel, a building system * Steel fence post *Trading post *Utility pole or utility post Military *Military base, an assigned station or a guard post **Outpost (military), a military outpost **Guardpost, or guardhouse Geography *Post, Iran, a vil ...
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Main Memory
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). This distinction was extended in the Von Neumann arch ...
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POST Card 98usd
Post or POST commonly refers to: *Mail, the postal system, especially in Commonwealth of Nations countries **An Post, the Irish national postal service **Canada Post, Canadian postal service **Deutsche Post, German postal service **Iraqi Post, Iraqi postal service **Russian Post, Russian postal service **Hotel post, a service formerly offered by remote Swiss hotels for the carriage of mail to the nearest official post office **United States Postal Service or USPS **Parcel post, a postal service for mail that is heavier than ordinary letters *Post, a job or occupation Post, POST, or posting may also refer to: Architecture and structures *Lamppost, a raised source of light on the edge of a road *Post (structural), timber framing *Post and lintel, a building system * Steel fence post *Trading post *Utility pole or utility post Military *Military base, an assigned station or a guard post **Outpost (military), a military outpost **Guardpost, or guardhouse Geography *Post, Iran, a vil ...
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POST Card 3usd
Post or POST commonly refers to: *Mail, the postal system, especially in Commonwealth of Nations countries **An Post, the Irish national postal service **Canada Post, Canadian postal service **Deutsche Post, German postal service **Iraqi Post, Iraqi postal service **Russian Post, Russian postal service **Hotel post, a service formerly offered by remote Swiss hotels for the carriage of mail to the nearest official post office **United States Postal Service or USPS **Parcel post, a postal service for mail that is heavier than ordinary letters *Post, a job or occupation Post, POST, or posting may also refer to: Architecture and structures *Lamppost, a raised source of light on the edge of a road *Post (structural), timber framing *Post and lintel, a building system * Steel fence post *Trading post *Utility pole or utility post Military *Military base, an assigned station or a guard post **Outpost (military), a military outpost **Guardpost, or guardhouse Geography *Post, Iran, a vil ...
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BIOS POST Card
In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the booting process (power-on startup). The BIOS firmware comes pre-installed on an IBM PC or IBM PC compatible's system board and exists in some UEFI-based systems to maintain compatibility with operating systems that do not support UEFI native operation. The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. The BIOS originally proprietary to the IBM PC has been reverse engineered by some companies (such as Phoenix Technologies) looking to create compatible systems. The interface of that original system serves as a ''de facto'' standard. The BIOS in modern PCs initializes and tests the system hardware components (Power-on self-test), and loads a boot loader from a mass storage device which then init ...
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Conventional Memory
In DOS memory management, conventional memory, also called base memory, is the first 640 kilobytes of the memory on IBM PC or compatible systems. It is the read-write memory directly addressable by the processor for use by the operating system and application programs. As memory prices rapidly declined, this design decision became a limitation in the use of large memory capacities until the introduction of operating systems and processors that made it irrelevant. 640 KB barrier The 640 KB barrier is an architectural limitation of IBM PC compatible PCs. The Intel 8088 CPU, used in the original IBM PC, was able to address 1 MB (220 bytes), since the chip offered 20 address lines. In the design of the PC, the memory below 640 KB was for random-access memory on the motherboard or on expansion boards, and it was called the conventional memory area. The first memory segment (64 KB) of the conventional memory area is named lower memory or low memory area. ...
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Random-access Memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to be read (computer), 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 tape data storage, magnetic tapes and drum memory), where 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 multiplexer, 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 ...
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Warm Boot
In computing, rebooting is the process by which a running computer system is restarted, either intentionally or unintentionally. Reboots can be either a cold reboot (alternatively known as a hard reboot) in which the power to the system is physically turned off and back on again (causing an initial boot of the machine); or a warm reboot (or soft reboot) in which the system restarts while still powered up. The term restart (as a system command) is used to refer to a reboot when the operating system closes all programs and finalizes all pending input and output operations before initiating a soft reboot. Terminology Etymology Early electronic computers (like the IBM 1401) had no operating system and little internal memory. The input was often a stack of punch cards or via a Switch Register. On systems with cards, the computer was initiated by pressing a start button that performed a single command - "read a card". This first card then instructed the machine to read more cards ...
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Flash Memory
Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both use the same cell design, consisting of floating gate MOSFETs. They differ at the circuit level depending on whether the state of the bit line or word lines is pulled high or low: in NAND flash, the relationship between the bit line and the word lines resembles a NAND gate; in NOR flash, it resembles a NOR gate. Flash memory, a type of floating-gate memory, was invented at Toshiba in 1980 and is based on EEPROM technology. Toshiba began marketing flash memory in 1987. EPROMs had to be erased completely before they could be rewritten. NAND flash memory, however, may be erased, written, and read in blocks (or pages), which generally are much smaller than the entire device. NOR flash memory allows a single machine word to be written to an era ...
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Northbridge (computing)
In computing, a northbridge (also host bridge, or memory controller hub) is one of two chips comprising the core logic chipset architecture on a PC motherboard. A northbridge is connected directly to a CPU via the front-side bus (FSB) to handle high-performance tasks, and is usually used in conjunction with a slower southbridge to manage communication between the CPU and other parts of the motherboard. Since the 2010s, die shrink and improved transistor density have allowed for increasing chipset integration, and the functions performed by northbridges are now often incorporated into other components (like southbridges or CPUs themselves). As of 2019, Intel and AMD had both released chipsets in which all northbridge functions had been integrated into the CPU. Modern Intel Core processors have the northbridge integrated on the CPU die, where it is known as the uncore or system agent. On older Intel based PCs, the northbridge was also named external memory controller hub ('' ...
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Hard Reboot
In computing, rebooting is the process by which a running computer system is restarted, either intentionally or unintentionally. Reboots can be either a cold reboot (alternatively known as a hard reboot) in which the power to the system is physically turned off and back on again (causing an initial boot of the machine); or a warm reboot (or soft reboot) in which the system restarts while still powered up. The term restart (as a system command) is used to refer to a reboot when the operating system closes all programs and finalizes all pending input and output operations before initiating a soft reboot. Terminology Etymology Early electronic computers (like the IBM 1401) had no operating system and little internal memory. The input was often a stack of punch cards or via a Switch Register. On systems with cards, the computer was initiated by pressing a start button that performed a single command - "read a card". This first card then instructed the machine to read more cards ...
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Reset Vector
In computing, the reset vector is the default location a central processing unit will go to find the first instruction it will execute after a reset. The reset vector is a pointer or address, where the CPU should always begin as soon as it is able to execute instructions. The address is in a section of non-volatile memory initialized to contain instructions to start the operation of the CPU, as the first step in the process of booting the system containing the CPU. Processors * The reset vector for the 8086 processor is at physical address FFFF0h (16 bytes below 1 MB). The value of the CS register at reset is FFFFh and the value of the IP register at reset is 0000h to form the segmented address FFFFh:0000h, which maps to physical address FFFF0h. * The reset vector for the 80286 processor is at physical address FFFFF0h (16 bytes below 16 MB). The value of the CS register at reset is F000h with the descriptor base set to FF0000h and the value of the IP register at reset ...
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