|
No Execute
The NX bit (no-execute bit) is a processor feature that separates areas of a virtual address space (the memory layout a program uses) into sections for storing data or program instructions. An operating system supporting the NX bit can mark certain areas of the virtual address space as non-executable, preventing the processor from running any code stored there. This technique, known as executable space protection or Write XOR Execute, protects computers from malicious software that attempts to insert harmful code into another program’s data storage area and execute it, such as in a buffer overflow attack. The term "NX bit" was introduced by Advanced Micro Devices (AMD) as a marketing term. Intel markets this feature as the XD bit (execute disable), while the MIPS architecture refers to it as the XI bit (execute inhibit). In the ARM architecture, introduced in ARMv6, it is known as XN (execute never). The term NX bit is often used broadly to describe similar executable space pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Processing Unit
A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary Processor (computing), processor in a given computer. Its electronic circuitry executes Instruction (computing), instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. This role contrasts with that of external components, such as main memory and I/O circuitry, and specialized coprocessors such as graphics processing units (GPUs). The form, CPU design, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic–logic unit (ALU) that performs arithmetic operation, arithmetic and Bitwise operation, logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates the #Fetch, fetching (from memory), #Decode, decoding and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Page (computer Memory)
A page, memory page, or virtual page is a fixed-length contiguous block of virtual memory, described by a single entry in a page table. It is the smallest unit of data for memory management in an operating system that uses virtual memory. Similarly, a page frame is the smallest fixed-length contiguous block of physical memory into which memory pages are mapped by the operating system. A transfer of pages between main memory and an auxiliary store, such as a hard disk drive, is referred to as paging or swapping. Explanation Computer memory is divided into pages so that information can be found more quickly. The concept is named by analogy to the pages of a printed book. If a reader wanted to find, for example, the 5,000th word in the book, they could count from the first word. This would be time-consuming. It would be much faster if the reader had a listing of how many words are on each page. From this listing they could determine which page the 5,000th word appears on, and h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until he was forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in the minicomputer market starting in the early 1960s. The company produced a series of machines known as the Programmed Data Processor, PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented the company's place as a leading vendor in the computer space. As microcomputers improved in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARMv8-A
ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of RISC instruction set architectures (ISAs) for computer processors. Arm Holdings develops the ISAs and licenses them to other companies, who build the physical devices that use the instruction set. It also designs and licenses cores that implement these ISAs. Due to their low costs, low power consumption, and low heat generation, ARM processors are useful for light, portable, battery-powered devices, including smartphones, laptops, and tablet computers, as well as embedded systems. However, ARM processors are also used for desktops and servers, including Fugaku, the world's fastest supercomputer from 2020 to 2022. With over 230 billion ARM chips produced, , ARM is the most widely used family of instruction set architectures. There have been several generations of the ARM design. The original ARM1 used a 32-bit internal structure but had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Execution Prevention
In computer security, executable-space protection marks memory regions as non-executable, such that an attempt to execute machine code in these regions will cause an exception. It relies on hardware features such as the NX bit (no-execute bit), or on software emulation when hardware support is unavailable. Software emulation often introduces a performance cost, or overhead (extra processing time or resources), while hardware-based NX bit implementations have no measurable performance impact. The Burroughs large systems, starting with the Burroughs 5000 introduced in 1961, implemented executable-space protection using a tagged architecture. All accesses to code and data took place through descriptors, which had memory tags preventing them from being modified; descriptors for code did not allow the code to be modified, and descriptors for data did not allow the data ta be executed as code. Today, operating systems use executable-space protection to mark writable memory areas, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Address Extension
In computing, Physical Address Extension (PAE), sometimes referred to as Page Address Extension, is a memory management feature for the x86 architecture. PAE was first introduced by Intel in the Pentium Pro, and later by AMD in the Athlon processor. It defines a page table hierarchy of three levels (instead of two), with table entries of 64 bits each instead of 32, allowing these CPUs to directly access a physical address space larger than 4 gigabytes (232 bytes). The page table structure used by x86-64 CPUs when operating in long mode further extends the page table hierarchy to four or more levels, extending the virtual address space, and uses additional physical address bits at all levels of the page table, extending the physical address space. It also uses the topmost bit of the 64-bit page table entry as a no-execute or "NX" bit, indicating that code cannot be executed from the associated page. The NX feature is also available in protected mode when these CPUs are run ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Page Table
A page table is a data structure used by a virtual memory system in a computer to store mappings between virtual addresses and physical addresses. Virtual addresses are used by the program executed by the accessing process, while physical addresses are used by the hardware, or more specifically, by the random-access memory (RAM) subsystem. The page table is a key component of virtual address translation that is necessary to access data in memory. The page table is set up by the computer's operating system, and may be read and written during the virtual address translation process by the memory management unit or by low-level system software or firmware. Role of the page table In operating systems that use virtual memory, every process is given the impression that it is working with large, contiguous sections of memory. Physically, the memory of each process may be dispersed across different areas of physical memory, or may have been moved ( paged out) to secondary storage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentium 4
Pentium 4 is a series of single-core central processing unit, CPUs for Desktop computer, desktops, laptops and entry-level Server (computing), servers manufactured by Intel. The processors were shipped from November 20, 2000 until August 8, 2008. All Pentium 4 CPUs are based on the NetBurst microarchitecture, the successor to the P6 (microarchitecture), P6. The Pentium 4 #Willamette, Willamette (180 nm) introduced SSE2, while the #Prescott, Prescott (90 nm) introduced SSE3 and later 64-bit technology. Later versions introduced Hyper-threading, Hyper-Threading Technology (HTT). The first Pentium 4-branded processor to implement x86-64, 64-bit was the Prescott (90 nm) (February 2004), but this feature was not enabled. Intel subsequently began selling 64-bit Pentium 4s using the ''"E0" revision'' of the Prescotts, being sold on the OEM market as the Pentium 4, model F. The E0 revision also adds eXecute Disable (XD) (Intel's name for the NX bit) to Intel 64. Int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opteron
Opteron is AMD's x86 former server and workstation Microprocessor, processor line, and was the first processor which supported the AMD64 instruction set architecture (known generically as x86-64). It was released on April 22, 2003, with the ''SledgeHammer'' core (K8) and was intended to compete in the Server (computing), server and workstation markets, particularly in the same segment as the Intel Xeon processor. Processors based on the AMD K10 microarchitecture (codenamed ''Barcelona'') were announced on September 10, 2007, featuring a new Multi-core processor, quad-core configuration. The last released Opteron CPUs are the Piledriver (microarchitecture), Piledriver-based Opteron 4300 and 6300 series processors, codenamed "Seoul" and "Abu Dhabi" respectively. In January 2016, the first ARM architecture#64.2F32-bit architecture, ARMv8-A based Opteron-branded SoC was released, though it is unclear what, if any, heritage this Opteron-branded product line shares with the original Op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athlon 64
The Athlon 64 is a ninth-generation, AMD64-architecture microprocessor produced by Advanced Micro Devices (AMD), released on September 23, 2003. It is the third processor to bear the name ''Athlon'', and the immediate successor to the Athlon XP. The Athlon 64 was the second processor to implement the AMD64 architecture (after the Opteron) and the first 64-bit processor targeted at the average consumer. Variants of the Athlon 64 have been produced for Socket 754, Socket 939, Socket 940, and Socket AM2. It was AMD's primary consumer CPU, and primarily competed with Intel's Pentium 4, especially the ''Prescott'' and ''Cedar Mill'' core revisions. The Athlon 64 is AMD's first K8, eighth-generation processor core for desktop and mobile computers. Despite being natively 64-bit, the AMD64 architecture is backward-compatible with 32-bit x86 instructions. The Athlon 64 line was succeeded by the dual-core Athlon 64 X2 and Athlon X2 lines. Background The Athlon 64 was originally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xeon
Xeon (; ) is a brand of x86 microprocessors designed, manufactured, and marketed by Intel, targeted at the non-consumer workstation, server, and embedded markets. It was introduced in June 1998. Xeon processors are based on the same architecture as regular desktop-grade CPUs, but have advanced features such as support for error correction code (ECC) memory, higher core counts, more PCI Express lanes, support for larger amounts of RAM, larger cache memory and extra provision for enterprise-grade reliability, availability and serviceability (RAS) features responsible for handling hardware exceptions through the Machine Check Architecture (MCA). They are often capable of safely continuing execution where a normal processor cannot due to these extra RAS features, depending on the type and severity of the machine-check exception (MCE). Some also support multi-socket systems with two, four, or eight sockets through use of the Ultra Path Interconnect (UPI) bus, which replaced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Celeron
Celeron is a series of IA-32 and x86-64 computer microprocessor, microprocessors targeted at low-cost Personal computer, personal computers, manufactured by Intel from 1998 until 2023. The first Celeron-branded CPU was introduced on April 15, 1998, and was based on the Pentium II. Celeron-branded processors released from 2009 to 2023 are compatible with IA-32 software. They typically offer less performance per clock speed compared to flagship Intel CPU lines, such as the Pentium or Intel Core, Core brands. They often have less CPU cache, cache or intentionally disabled advanced features, with variable impact on performance. While some Celeron designs have achieved strong performance for their segment, the majority of the Celeron line has exhibited noticeably degraded performance. This has been the primary Market segmentation, justification for the higher cost of other Intel CPU brands versus the Celeron range. In September 2022, Intel announced that the Celeron brand, along wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
