Making Utilities for MS-DOS :: Microsoft Computers System Software Essays

Making Utilities for MS-DOSThese days, when calculators play an important role in virtually all aspects ofour life, the issue of concern to many programmers is Microsofts hiding oftechnical documentation. Microsoft is by far the most important carcass softwaredeveloper. on that point sack up be no argument rough that. Microsofts MS-DOS operate form has f etc. a de facto standard (IBMs PC-DOS is actually a licensedversion of MS-DOS). And this should be so, because these systems are very well indite. The people who designed them are maybe the best software engineers inthe world.But making a computer platform that is a de facto standard should imply a good trade of responsibility before the developers who make applications for thatplatform. In particular, proper documentation is requisite for much(prenominal) a platform.Not providing enough documentation for a system that everyone uses can havedisastrous results. Think of it, an operating system is unimportant by itself, its sole purpose is to provide services to applications. And who would be qualified todevelop applications for an operating system if the documentation for thatsystem is confidential and unattached only to the company that developed it?Obviously, only the company that has developed that operating system will beable to develop software for it. And this is a violation of the Antitrust Law.And now I start having a hesitancy that this is happening with Microsoftsoperating systems. It should be no secret to anyone that MS-DOS contains a bevyof undocumented system calls, data structures and other features. Numerous bookshave been written on this subject (see bibliography). Many of them are vital tosystem programming. There is no way to write a piece of system software, such asa multitasker, a local area network, or another(prenominal) operating system extension,without knowing this undocumented functionality in MS-DOS. And, sure enough,Microsoft is utilise this functionality extensively when developing operatingsystem extensions. For example, Microsoft Windows, Microsoft Network, andMicrosoft CD-ROM Extensions (MSCDEX) rely heavy on the undocumented internalsof MS-DOS.The reader can ask, Why do they permit functionality undocumented? To answerthat question, we should look at what this functionality actually is. In MS-DOS, the undocumented functionality is actually the internal structures thatMS-DOS uses to implement its documented INT 21h API. Any operating system musthave some internal structures in which it keeps information about disk drives,open files, network connections, alien file systems, running tasks, etc. And MS-DOS (later Ill call it simply DOS) has internal structures too. Thesestructures form the core of undocumented functionality in MS-DOS. Thisoperating system also has some undocumented INT 21h API functions, unless they