IBM BASICA is a disk-based BASIC

BASIC

BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....

 interpreter written by Microsoft

Microsoft

Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 for PC-DOS

PC-DOS

IBM PC DOS is a DOS system for the IBM Personal Computer and compatibles, manufactured and sold by IBM from the 1980s to the 2000s....

. BASICA used the ROM

Read-only memory

Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...

-resident code of "IBM Cassette BASIC

IBM Cassette BASIC

IBM Cassette BASIC was a version of the Microsoft BASIC programming language licensed by IBM for the IBM PC. It was included in the BIOS ROM of the original IBM PC. Cassette BASIC provided the default user interface if there was no floppy disk drive installed, or if the boot code did not find a...

" which was included with early models of IBM's PC. It added functions such as diskette file access, storing programs on disk, and monophonic music through the PC's built-in speaker. BASICA would not run on non-IBM computers (even so-called "100% compatible" machines) or later IBM models, since those lack the needed ROM BASIC.

Operation

BASICA was loaded when its name was typed at a DOS command prompt, with some optional parameters to control allocation of memory. When loaded, it displayed a sign-on identification message. The programmer could then enter in an entire program line by line, by entering the line number before the statement. Statements entered without a line number were executed in immediate mode. The function keys were assigned common commands, which were displayed at the bottom of the screen. Program source was stored internally in a compact tokenized form, where keywords were replaced with a single byte token, to save space and save execution time. Programs could be saved in tokenized form, or optionally saved as DOS text ASCII files that could be viewed and edited with other programs. Like most other MS-DOS/PC-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 5150. Disk BASIC

IBM Disk BASIC

IBM Disk BASIC was a version of the Microsoft BASIC programming language licensed by IBM for the IBM PC DOS. It was included in the original IBM PC DOS and required the original IBM PC BIOS to run. The name Disk BASIC came from its use of floppy disks rather than cassette tapes to store programs...

 (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.

External links

• A brief history of the development of BASIC