IBM Disk BASIC was a version of the Microsoft BASIC

Microsoft BASIC

Microsoft BASIC was the foundation product of the Microsoft company. It first appeared in 1975 as Altair BASIC, which was the first BASIC, and the first high level programming language available for the MITS Altair 8800 hobbyist microcomputer....

 programming language licensed by IBM

IBM

International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 for the IBM PC DOS. It was included in the original IBM PC DOS and required the original IBM PC BIOS

BIOS

In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....

 to run. The name Disk BASIC came from its use of floppy disk

Floppy disk

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

s rather than cassette tapes to store programs and data. GW BASIC is a standalone compatible successor of IBM Disk BASIC that doesn't require the original IBM PC BIOS to run. A later version IBM BASICA (short for "Advanced BASIC") added features to support graphics, sound (on the built-in speaker), and event handling for communications and joystick presses. Neither version of IBM BASIC would run on on non-IBM computers or later IBM models, since those lack the needed ROM BASIC; the equivalent to BASICA for non-IBM MS DOS compatible computers was GW-BASIC

GW-BASIC

GW-BASIC was a dialect of the programming language BASIC developed by Microsoft from BASICA, originally for Compaq. It is compatible with Microsoft/IBM BASICA, but was disk based and did not need the ROM BASIC. It was bundled with MS-DOS operating systems on IBM PC compatibles by Microsoft...

.

Operation

BASIC was loaded when its name was typed at a command prompt, with some optional parameters to control allocation of memory. When loaded, it displayed a sign-on identification message and started a full-screen text editor. The function keys were assigned common commands, which were displayed at the bottom of the screen. Commands could be typed in to load and save programs, and expressions could be typed in and executed in immediate mode. If a line of input started with a number, the language system stored the following line of text as part of program source. When listed on screen, lines were displayed in order of increasing line number. Changes could be made to a displayed line of program source code by moving the cursor to the line with the cursor keys, and typing over the on-screen text. Program source was stored internally in a tokenized form, where keywords were replaced with a single byte token, to save space and save execution time. Programs could be saved in compact tokenized form, or optionally saved as DOS text ASCII files that could be viewed and edited with other programs. Like most other MS DOS applications, BASICA was a text-mode program and had no features for windows, icons, mouse support, or cut and paste editing.

Versions

IBM personal computers came with several versions of BASIC. Cassette BASIC was built into the BIOS ROMs of the original PC and XT, and early models in the PS/2 line. It only supported a cassette tape interface for loading and saving programs, which was unavailable on models after the original Model 5150. Disk BASIC (BASIC.COM) added functions to use files on diskette, and also supported the serial port

Serial port

In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...

. It made use of the cassette BASIC ROM software and so would not run on machines not equipped with the IBM ROMs. Advanced BASIC (BASICA.COM) provided event trapping, extended support for monophonic sound (using the PC's built-in speaker), and graphics functions to set and clear pixels, draw lines and circles, and set colors. Advanced BASIC also required the casssette ROMs to function. A cartridge version of BASIC was only available on the IBM PCjr

IBM PCjr

The IBM PCjr was IBM's first attempt to enter the home computer market. The PCjr, IBM model number 4860, retained the IBM PC's 8088 CPU and BIOS interface for compatibility, but various design and implementation decisions led the PCjr to be a commercial failure.- Features :Announced November 1,...

 and supported the additional graphics modes and sounds possible on that platform.

GW-BASIC

GW-BASIC

GW-BASIC was a dialect of the programming language BASIC developed by Microsoft from BASICA, originally for Compaq. It is compatible with Microsoft/IBM BASICA, but was disk based and did not need the ROM BASIC. It was bundled with MS-DOS operating systems on IBM PC compatibles by Microsoft...

 was a Microsoft product distributed with non-IBM MS DOS computers, and supported all the graphics modes and features of BASICA on computers that did not have the IBM cassette BASIC.

The successor to BASICA for MS-DOS and PC-DOS versions was QBasic

QBasic

QBasic is an IDE and interpreter for a variant of the BASIC programming language which is based on QuickBASIC. Code entered into the IDE is compiled to an intermediate form, and this intermediate form is immediately interpreted on demand within the IDE. It can run under nearly all versions of DOS...

, which was a stripped-down version of the Microsoft QuickBASIC

QuickBASIC

Microsoft QuickBASIC is an Integrated Development Environment and compiler for the BASIC programming language that was developed by Microsoft. QuickBASIC runs mainly on DOS, though there was a short-lived version for Mac OS...

compiler that could not save executable files.