Original author(s) | Tim Paterson |
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Developer(s) | Microsoft |
Operating system | DOS, MS-DOS, OS/2, Microsoft Windows |
Type | Debugger |
Website | Debug |
debug
is a command in DOS, MS-DOS, OS/2 and Microsoft Windows (only x86 versions, not x64[1]) which runs the program debug.exe (or DEBUG.COM in older versions of DOS).[2] Debug can act as an assembler, disassembler, or hex dump program allowing users to interactively examine memory contents (in assembly language, hexadecimal or ASCII), make changes, and selectively execute COM, EXE and other file types. It also has several subcommands which are used to access specific disk sectors, I/O ports and memory addresses.[3] MS-DOS Debug runs at a 16-bit process level and therefore it is limited to 16-bit computer programs.[2] FreeDOS Debug has a "DEBUGX" version supporting 32-bit DPMI programs as well.[4]
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Traditionally, all computers and operating systems have included a maintenance function, used to determine whether a program is working correctly. Debug was written by Tim Paterson to serve this purpose in QDOS. When Paterson began working for Microsoft in the early 1980s he brought the program with him. Debug was part of DOS 1.00 and has been included in MS-DOS and Microsoft Windows. MS-DOS debug has several limitations:
32-bit Debug clones, such as FreeDOS Debug, have been written.[4]
debug [[Drive:][Path] FileName [parameters]]
When Debug is started without any parameters the Debug prompt, a "-", appears. The user can then enter one of several one or two-letter subcommands, including "a" to enter the assembler mode, "d" to perform a hexadecimal dump, "t" to trace and "u" to unassemble (disassemble) a program in memory.[5] Debug can also be used as a "debug script" interpreter using the following syntax.
debug < FileName
A script file may contain Debug subcommands and assembly language instructions.[3] This method can be used to create or edit binary files from batch files.[2]
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