Microsoft released the first version of QuickBASIC on August 18, 1985 on a single 5.25″ 360kB floppy disk. QuickBASIC version 2.0 and later contained an Integrated Development Environment (IDE), allowing users to edit directly in its on-screen text editor.
Although still supported in QuickBASIC, line numbers became optional. Program jumps also worked with named labels. Later versions also added control structures, such as multiline conditional statements and loop blocks.
Microsoft’s “PC BASIC Compiler” was included for compiling programs into DOS executables. Beginning with version 4.0, the editor included an interpreter that allowed the programmer to run the program without leaving the editor. The interpreter was used to debug a program before creating an executable file. Unfortunately, there were some subtle differences between the interpreter and the compiler, which meant that large programs that ran correctly in the interpreter might fail after compilation, or not compile at all because of differences in the memory management routines.
The last version of QuickBASIC was version 4.5 (1988), although development of the Microsoft BASIC Professional Development System (PDS) continued until its last release of version 7.1 in October 1990. At the same time, the QuickBASIC packaging was silently changed so that the disks used the same compression used for BASIC PDS 7.1. The Basic PDS 7.x version of the IDE was called QuickBASIC Extended (QBX), and it only ran on DOS, unlike the rest of Basic PDS 7.x, which also ran on OS/2. The successor to QuickBASIC and Basic PDS was Visual Basic for MS-DOS 1.0, shipped in Standard and Professional versions. Later versions of Visual Basic did not include DOS versions, as Microsoft concentrated on Windows applications.
A subset of QuickBASIC 4.5, named QBasic, was included with MS-DOS 5 and later versions, replacing the GW-BASIC included with previous versions of MS-DOS. Compared to QuickBASIC, QBasic is limited to an interpreter only, lacks a few functions, can only handle programs of a limited size, and lacks support for separate program modules. Since it lacks a compiler, it cannot be used to produce executable files, although its program source code can still be compiled by a QuickBASIC 4.5, PDS 7.x or VBDOS 1.0 compiler, if available.
QuickBASIC 1.00 for the Apple Macintosh operating system was launched in 1988. It was officially supported on machines running System 6 with at least 1 MB of RAM. QuickBASIC could also be run on System 7, as long as 32-bit addressing was disabled; this was not possible on Motorola 68040-based Macintosh machines.