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Machine Code
In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Although decimal computers were once common, the contemporary marketplace is dominated by binary computers; for those computers, machine code is "the binary representation of a computer program which is actually read and interpreted by the computer. A program in machine code consists of a sequence of machine instructions (possibly interspersed with data)." Each instruction causes the CPU to perform a very specific task, such as a load, a store, a jump, or an arithmetic logic unit (ALU) operation on one or more units of data in the CPU's registers or memory. Early CPUs had specific machine code that might break backward compatibility with each new CPU released. The notion of an instruction set architecture (ISA) defines and specifies the behavior and encoding in memory of the instruction set of the sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
W65C816S Machine Code Monitor
The W65C816S (also 65C816 or 65816) is an 8/16-bit microprocessor (MPU) developed and sold by the Western Design Center (WDC). Introduced in 1985, the W65C816S is an enhanced version of the WDC 65C02 8-bit MPU, itself a CMOS enhancement of the venerable MOS Technology 6502 NMOS MPU. The 65C816 was the CPU for the Apple IIGS and, in modified form, the Super Nintendo Entertainment System. The ''65'' in the part's designation comes from its 65C02 compatibility mode, and the ''816'' signifies that the MPU has selectable 8- and 16-bit computing, 16-bit processor register, register sizes. In addition to the availability of 16-bit registers, the W65C816S features extended memory addressing to 24-bit computing, 24 bits, supporting up to 16 megabytes of random-access memory, an enhanced instruction set, and a 16 bit Stack (data structure), stack pointer, as well as several new electrical signals for improved system hardware management. At reset (computing), reset, the W65C816S starts i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assembly Language
In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported. The first assembly code in which a language is used to represent machine code instructions is found in Kathleen and Andrew Donald Booth's 1947 work, ''Coding for A.R.C.''. Assembly code is converted into executable machine code by a utility program referred to as an ''assembler''. The term "assembler" is generally attributed to Wilkes, Wheeler and Gill in their 1951 book ''The Preparation of Programs for an Electronic Digital Com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Set
In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ''implementation''. In general, an ISA defines the supported instructions, data types, 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 characteristics such as performance, physical size, and monetary cost (among other things), but that are capable of running the same machine code, so that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micro-operation
In computer central processing units, micro-operations (also known as micro-ops or μops, historically also as micro-actions) are detailed low-level instructions used in some designs to implement complex machine instructions (sometimes termed macro-instructions in this context). Usually, micro-operations perform basic operations on data stored in one or more registers, including transferring data between registers or between registers and external buses of the central processing unit (CPU), and performing arithmetic or logical operations on registers. In a typical fetch-decode-execute cycle, each step of a macro-instruction is decomposed during its execution so the CPU determines and steps through a series of micro-operations. The execution of micro-operations is performed under control of the CPU's control unit, which decides on their execution while performing various optimizations such as reordering, fusion and caching. Optimizations Various forms of μops have long bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcode
In processor design, microcode (μcode) is a technique that interposes a layer of computer organization between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. Microcode is a layer of hardware-level instructions that implement higher-level machine code instructions or internal finite-state machine sequencing in many digital processing elements. Microcode is used in general-purpose central processing units, although in current desktop CPUs, it is only a fallback path for cases that the faster hardwired control unit cannot handle. Microcode typically resides in special high-speed memory and translates machine instructions, state machine data, or other input into sequences of detailed circuit-level operations. It separates the machine instructions from the underlying electronics so that instructions can be designed and altered more freely. It also facilitates the building of complex multi-step instructions, while red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bytecode
Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references (normally numeric addresses) that encode the result of compiler parsing and performing semantic analysis of things like type, scope, and nesting depths of program objects. The name bytecode stems from instruction sets that have one-byte opcodes followed by optional parameters. Intermediate representations such as bytecode may be output by programming language implementations to ease interpretation, or it may be used to reduce hardware and operating system dependence by allowing the same code to run cross-platform, on different devices. Bytecode may often be either directly executed on a virtual machine (a p-code machine, i.e., interpreter), or it may be further compiled into machine code for better performance. Since bytecode instructions ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interpreter (computing)
In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program. An interpreter generally uses one of the following strategies for program execution: # Parse the source code and perform its behavior directly; # Translate source code into some efficient intermediate representation or object code and immediately execute that; # Explicitly execute stored precompiled bytecode made by a compiler and matched with the interpreter Virtual Machine. Early versions of Lisp programming language and minicomputer and microcomputer BASIC dialects would be examples of the first type. Perl, Raku, Python, MATLAB, and Ruby are examples of the second, while UCSD Pascal is an example of the third type. Source programs are compiled ahead of time and stored as machine independent code, which is then linked at run-time and executed by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compiler
In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program. Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Ravi Sethi, Jeffrey D. Ullman - Second Edition, 2007 There are many different types of compilers which produce output in different useful forms. A ''cross-compiler'' produces code for a different CPU or operating system than the one on which the cross-compiler itself runs. A ''bootstrap compiler'' is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software include, a program that translates from a low-level language to a h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-level Programming Language
In computer science, a high-level programming language is a programming language with strong Abstraction (computer science), abstraction from the details of the computer. In contrast to low-level programming languages, it may use natural language ''elements'', be easier to use, or may automate (or even hide entirely) significant areas of computing systems (e.g. memory management), making the process of developing a program simpler and more understandable than when using a lower-level language. The amount of abstraction provided defines how "high-level" a programming language is. In the 1960s, a high-level programming language using a compiler was commonly called an ''autocode''. Examples of autocodes are COBOL and Fortran. The first high-level programming language designed for computers was Plankalkül, created by Konrad Zuse. However, it was not implemented in his time, and his original contributions were largely isolated from other developments due to World War II, aside from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disassembly
A disassembler is a computer program that translates machine language into assembly language—the inverse operation to that of an assembler. A disassembler differs from a decompiler, which targets a high-level language rather than an assembly language. Disassembly, the output of a disassembler, is often formatted for human-readability rather than suitability for input to an assembler, making it principally a reverse-engineering tool. Assembly language source code generally permits the use of constants and programmer comments. These are usually removed from the assembled machine code by the assembler. If so, a disassembler operating on the machine code would produce disassembly lacking these constants and comments; the disassembled output becomes more difficult for a human to interpret than the original annotated source code. Some disassemblers provide a built-in code commenting feature where the generated output gets enriched with comments regarding called API functions or parame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patch (computing)
A patch is a set of changes to a computer program or its supporting data designed to update, fix, or improve it. This includes fixing security vulnerabilities and other bugs, with such patches usually being called bugfixes or bug fixes. Patches are often written to improve the functionality, usability, or performance of a program. The majority of patches are provided by software vendors for operating system and application updates. Patches may be installed either under programmed control or by a human programmer using an editing tool or a debugger. They may be applied to program files on a storage device, or in computer memory. Patches may be permanent (until patched again) or temporary. Patching makes possible the modification of compiled and machine language object programs when the source code is unavailable. This demands a thorough understanding of the inner workings of the object code by the person creating the patch, which is difficult without close study of the sourc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debugging
In computer programming and software development, debugging is the process of finding and resolving '' bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve interactive debugging, control flow analysis, unit testing, integration testing, log file analysis, monitoring at the application or system level, memory dumps, and profiling. Many programming languages and software development tools also offer programs to aid in debugging, known as ''debuggers''. Etymology The terms "bug" and "debugging" are popularly attributed to Admiral Grace Hopper in the 1940s. While she was working on a Mark II computer at Harvard University, her associates discovered a moth stuck in a relay and thereby impeding operation, whereupon she remarked that they were "debugging" the system. However, the term "bug", in the sense of "technical error", dates back at least to 1878 and Thomas Edison who describes the "litt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
