![IBM PC ROM BIOS and IBM PC ROM BASIC (1981) b](https://upload.wikimedia.org/wikipedia/commons/a/a3/IBM_PC_ROM_BIOS_and_IBM_PC_ROM_BASIC_%281981%29_b.jpg)
The IBM Personal Computer Basic, commonly shortened to IBM BASIC, is a
programming language
A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
The description of a programming ...
first released by
IBM with the
IBM Personal Computer, Model 5150 (IBM PC) in 1981. IBM released four different versions of the
Microsoft BASIC interpreter, licensed from
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...
for the PC and
PCjr. They are known as Cassette BASIC, Disk BASIC, Advanced BASIC (BASICA), and Cartridge BASIC. Versions of Disk BASIC and Advanced BASIC were included with
IBM PC DOS up to PC DOS 4. In addition to the features of an
ANSI standard
BASIC
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
, the IBM versions offered support for the graphics and sound hardware of the IBM PC line. Source code could be typed in with a full-screen editor, and very limited facilities were provided for rudimentary program
debugging
In computer programming and software development, debugging is the process of finding and resolving '' bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems.
Debugging tactics can involve in ...
. IBM also released a version of the Microsoft BASIC
compiler
In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that ...
for the PC, concurrently with the release of PC DOS 1.10 in 1982.
Background
IBM licensed Microsoft BASIC for the IBM Personal Computer, despite already having its own version of BASIC for the company's mainframes.
Don Estridge
Philip Donald Estridge (June 23, 1937 – August 2, 1985), known as Don Estridge, was an American computer engineer who led development of the original IBM Personal Computer (PC), and thus is known as the "father of the IBM PC". His decisions dra ...
said, "Microsoft BASIC had hundreds of thousands of users around the world. How are you going to argue with that?"
IBM Cassette BASIC
''IBM Cassette BASIC'' came in 32
kilobyte
The kilobyte is a multiple of the unit byte for digital information.
The International System of Units (SI) defines the prefix ''kilo'' as 1000 (103); per this definition, one kilobyte is 1000 bytes.International Standard IEC 80000-13 Quantiti ...
s (KB) of
read-only memory
Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing sof ...
(ROM), separate from the 8 KB
BIOS
In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the ...
ROM of the original IBM PC, and did not require an
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
to run. Cassette BASIC provided the default user interface invoked by the BIOS through
INT 18h if there was no floppy disk drive installed, or if the
boot code did not find a bootable floppy disk at power up. The name Cassette BASIC came from its use of
cassette tape
The Compact Cassette or Musicassette (MC), also commonly called the tape cassette, cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. Invented by Lou Ottens ...
s rather than floppy disks to store programs and data. Cassette BASIC was built into the ROMs of the original PC and
XT, and early models in the
PS/2
The Personal System/2 or PS/2 is IBM's second generation of personal computers. Released in 1987, it officially replaced the IBM PC, XT, AT, and PC Convertible in IBM's lineup. Many of the PS/2's innovations, such as the 16550 UART (serial po ...
line. It only supports loading and saving programs to the
IBM cassette tape interface, which is unavailable on models after the original Model 5150. The entry-level version of the 5150 came with just 16 KB of
random-access memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to b ...
(RAM), which was sufficient to run Cassette BASIC. However, Cassette BASIC was rarely used because few PCs were sold without a disk drive, and most were sold with PC DOS and sufficient RAM to at least run Disk BASIC—many could run Advanced BASIC as well. There are three versions of Cassette BASIC: C1.00 (found on the early IBM PCs with 16–64K motherboards), C1.10 (found on all later IBM PCs, XTs, ATs, and PS/2s), and C1.20 (found on the PCjr).
IBM Disk BASIC
''IBM Disk BASIC (BASIC.COM)'' was included in the original
IBM PC DOS. Because it uses the 32 KB Cassette BASIC ROM,
BASIC.COM did not run on even highly compatible
PC clones
IBM PC compatible computers are similar to the original IBM PC, XT, and AT, all from computer giant IBM, that are able to use the same software and expansion cards. Such computers were referred to as PC clones, IBM clones or IBM PC clones. ...
, such as the
Compaq Portable
The Compaq Portable was an early portable computer which was one of the first IBM PC compatible systems. It was Compaq Computer Corporation's first product, to be followed by others in the Compaq Portable series and later Compaq Deskpro series. ...
.
The name Disk BASIC came from its use of
floppy disk
A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined w ...
s as well as
cassette tape
The Compact Cassette or Musicassette (MC), also commonly called the tape cassette, cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. Invented by Lou Ottens ...
s to store programs and data. Disk-based code corrected
errata
An erratum or corrigendum (plurals: errata, corrigenda) (comes from la, errata corrige) is a correction of a published text. As a general rule, publishers issue an erratum for a production error (i.e., an error introduced during the publishing pro ...
in the ROM-resident code and added floppy disk and
serial port support.
Disk BASIC can be identified by its use of the letter D preceding the version number. It adds disk support and some features lacking in Cassette BASIC, but does not include the extended sound/graphics functions of BASICA. The primary purpose of Disk BASIC was as a "light" version for IBM PCs with only 48 KB of memory: BASIC.COM would then have about 23 KB free for user code, whereas BASICA would only have about 17 KB. By 1986, all new PCs shipped with at least 256k and DOS versions after 3.00 reduced Disk BASIC to only a small stub that called BASICA.COM for compatibility with batch files. Even with all this excess RAM, BASIC would still only allocate and manage just under 61 KB for user programs, whether it was Cassette BASIC, BASIC.COM or BASICA.
IBM Advanced BASIC
''IBM Advanced BASIC (BASICA.COM)'' was also included in the original IBM PC DOS, and required the ROM-resident code of Cassette BASIC. It adds functions such as diskette file access, storing programs on disk, monophonic sound using the PC's built-in speaker, graphics functions to set and clear pixels, draw lines and circles, and set colors, and event handling for communications and joystick presses. BASICA will not run on non-IBM computers (even so-called "100% compatible" machines) or later IBM models, since those lack the needed ROM BASIC.
BASICA versions are the same as their respective DOS, beginning with v1.00 and ending with v3.30. The early versions of BASICA do not support subdirectories and some graphics commands functioned slightly differently. As an example, if the LINE statement was used to draw lines that trailed off-screen, BASIC merely intersects them with the nearest adjacent line while in BASIC 2.x and up, they go off the screen and do not intersect. The PAINT command in BASIC 1.x begins filling at the coordinate specified and expands outward in alternating up and down directions while in BASIC 2.x it fills everything below the starting coordinate and then after finishing, everything above it. BASIC 1.x's PAINT command also makes use of the system stack for storage and when filling in complex areas, it is possible to produce an OVERFLOW error. To remedy this, the CLEAR statement can be used to expand BASIC's stack (128 bytes is the default size). BASIC 2.x does not use the stack when PAINTing and thus is free of this problem.
Compaq BASIC 1.13 was the first standalone BASIC for the PC (that did not require Cassette BASIC to run) as well as the only version of BASIC besides IBM BASICA 1.00 and 1.10 to use FCBs and include the original LINE statement with intersecting lines (the PAINT statement in Compaq BASIC 1.13 worked like in all later versions of BASICA/GW-BASIC, using the new fill algorithm and no stack).
Early versions of PC DOS include several sample BASIC programs demonstrating the capabilities of the PC, including the BASICA game ''
DONKEY.BAS
''Donkey'', often known by its filename ''DONKEY.BAS'', is a video game written in 1981, and included with early versions of the IBM PC DOS operating system distributed with the original IBM PC. It is a top-down driving game in which the player mu ...
''.
GW-BASIC is identical to BASICA, with the exception of including the Cassette BASIC code in the program, thus allowing it to run on non-IBM computers and later IBM models that lack Cassette BASIC in ROM.
IBM PCjr Cartridge BASIC
A
ROM cartridge
A ROM cartridge, usually referred to in context simply as a cartridge, cart, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, electroni ...
version of BASIC was only available on the
IBM PCjr
The IBM PCjr (pronounced "PC junior") was a home computer produced and marketed by IBM from March 1984 to May 1985, intended as a lower-cost variant of the IBM PC with hardware capabilities better suited for video games, in order to compete mor ...
, shipped in 1984, and supports the additional graphics modes and sound capabilities possible on that machine. It is a superset of advanced BASIC. Cartridge BASIC can only operate within the first 128 KB of memory on the PCjr and will not work with expansion RAM, ''i.e.'', the DEF SEG function cannot be used to point to memory segments above &H1FF0.
Cartridge BASIC is activated by typing BASICA at the DOS prompt. Conversely, IBM BASICA versions 2.1 and up will refuse to run if it detects a PCjr, but can be patched to work around this.
Operation
Cassette BASIC loads when a PC or PCjr is booted without a bootable disk or cartridge. Disk BASIC and Advanced BASIC load when their
command
Command may refer to:
Computing
* Command (computing), a statement in a computer language
* COMMAND.COM, the default operating system shell and command-line interpreter for DOS
* Command key, a modifier key on Apple Macintosh computer keyboards
* ...
name (BASIC and BASICA respectively) is typed at a DOS command prompt (except PCjr, which activates Cartridge BASIC instead), with some optional parameters to control allocation of memory. When loaded, a sign-on identification message displays the program version number, and a full-screen text editor starts (see images, right). The function keys are assigned common commands, which display at the bottom of the screen. Commands may be typed in to load or save programs, and expressions can be typed in and executed in
direct (immediate) mode. If a line of input starts with a number, the language system stores the following line of text as part of program source, allowing a programmer to enter in an entire program line by line, entering line numbers before each statement. When listed on screen, lines are displayed in order of increasing line number. Changes can 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 is stored internally in a
tokenized form, where
reserved words are replaced with a single
byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
token, to save space and execution time. Programs may be saved in compact tokenized form, or optionally saved as DOS
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
text files
[DOS text files terminate each line with a CR (carriage return, ASCII 13) and LF (linefeed, ASCII 10) character pair, in that order.] that can be viewed and edited with other programs. Like most other DOS applications, IBM BASIC is a
text-mode program and has no features for windows, icons, mouse support, or cut-and-paste editing.
Legacy
GW-BASIC, launched in 1983, is a disk-based Microsoft product that was distributed with non-IBM
MS-DOS
MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...
computers, and supports all the graphics modes and features of BASICA on computers that do not have IBM Cassette BASIC.
The successor to BASICA for MS-DOS and PC DOS versions, now discontinued, is
QBasic
QBasic is an integrated development environment (IDE) and interpreter for a variety of dialects of BASIC which are based on QuickBASIC. Code entered into the IDE is compiled to an intermediate representation (IR), and this IR is immediately ex ...
, launched in 1991. It is a stripped-down version of the Microsoft
QuickBASIC compiler: QBasic is an interpreter and cannot compile source files, while QuickBASIC can compile and save the programs in the .EXE executable file format. QuickBASIC also includes certain advanced language statements and functions (mostly involving OS interfacing and low-level machine language programming), supports multi-module programs, and includes advanced debugging features, all of which are absent from QBASIC.
References
External links
A brief history of the development of BASICwww.phys.uu.nl/~bergmann/history.html (archived)
PCE IBM PC Emulatornbsp;— emulates IBM Cassette BASIC and IBM Cassette Interface with connected third party cassette drive
which invokes & copies IBM Cassette BASIC
{{Authority control
BASIC interpreters
Discontinued Microsoft BASICs
Programming languages created in 1981
BASIC
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
BASIC
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
BASIC programming language family
Microsoft programming languages