Editing Paradox (database) (section)

==Paradox for DOS==
'''Paradox for DOS''' was a [[relational database management system]] originally written by Richard Schwartz and [[Robert Shostak]], and released by their Belmont, California-based<ref name=AnsaSold.NYT87/> company Ansa Software in 1985.<ref name=Ansa695.NYT85/>

''The New York Times'' described it as "among the first of an emerging generation of software making extensive use of artificial intelligence techniques," and noted that ''Paradox'' could read the competing Ashton Tate's dBase files.<ref name=Ansa695.NYT85/>

In September 1987, [[Borland]] purchased Ansa Software, including their Paradox/DOS 2.0 software.<ref name=AnsaSold.NYT87>{{cite news |newspaper=[[The New York Times]]
   |url=https://www.nytimes.com/1987/07/10/business/company-news-ansa-is-acquired.html
   |title=Ansa is acquired  |date=July 10, 1987}}</ref> Notable classic versions were 3.5 and 4.5. Versions up to 3.5 were evolutions from 1.0. Version 4.0 and 4.5 were retooled in the Borland C++ windowing toolkit and used a different [[extended memory]] access scheme.

Paradox/DOS was a successful DOS-based database of the late 1980s and early 1990s. At that time, [[dBase]] and its [[xBase]] clones ([[Visual FoxPro|Foxpro]], [[Clipper (programming language)|Clipper]]) dominated the market. Other notable competitors were [[Clarion (programming language)|Clarion]], [[DataEase]], [[R:Base]], and [[DataFlex]].

The features that distinguished Paradox/DOS were:
* An enhanced design and implementation of visual [[Query by Example]] that was supported by an [[artificial intelligence|AI]] engine for [[heuristic (computer science)|heuristic]], dynamic [[query optimization]].
* Effective use of conventional, [[extended memory|extended]], and [[expanded memory|expanded]] memory – caching data tables and particularly indexes, which caused Paradox to execute tasks very quickly in contrast to the explicit skills required for xBase performance optimisation.<ref group="n">Unfortunately, the memory management of Paradox 3.5 and earlier is based on the early [[VCPI|Virtual Control Program Interface]] standard, so they will not run in modern DOS emulators, nor in pseudo-DOS environments like Windows 95. Paradox DOS 4.0 and 4.5 run fine under all 32-bit versions of Windows except Windows 2000, which causes a choice of two uncorrectable abort failures.  It does not run under 64-bit systems.</ref>
* An innovative programming language, the Paradox Application Language (PAL), that was readable, powerful, and could be recorded from keyboard actions (rather like [[Lotus 1-2-3]] macro recording).
*[[Lotus 1-2-3|Lotus]]-like text menus and windows, which was the native interface (in contrast to dBase, which had a command-line interface with menus layered on top).
* Particularly in Paradox 1.0 and 2.0, the user and programming manuals won [[readability]] awards <ref name=Para95.NYT/> – they were copiously illustrated, well laid out, and explanations were written in common English.

There are a few MSDOS emulators, among which are [[dbDOS]] (a paid-for product) and <nowiki>https://www.vdos.info/</nowiki> (which has a freeware option), both of which provide the ability to run Paradox for DOS applications (such as Paradox 4.5 for DOS) on Windows Vista and above 64-bit operating systems.