BASIC

BASIC (Beginners' All-purpose Symbolic Instruction Code)^[1] 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 in 1963. They wanted to enable students in non-scientific fields to use computers. At the time, nearly all computers required writing custom software, which only scientists and mathematicians tended to learn.

In addition to the programming language, Kemeny and Kurtz developed the

The emergence of

BASIC declined in popularity in the 1990s, as more powerful microcomputers came to market and programming languages with advanced features (such as Pascal and C) became tenable on such computers. By then, most nontechnical personal computer users relied on pre-written applications rather than writing their own programs. In 1991, Microsoft released Visual Basic, combining an updated version of BASIC with a visual forms builder. This reignited use of the language and "VB" remains a major programming language^[2][3] in the form of VB.NET, while a hobbyist scene for BASIC more broadly continues to exist.^[4][5]

Origin

John G. Kemeny was the chairman of the Dartmouth College Mathematics Department. Based largely on his reputation as an innovator in math teaching, in 1959 the College won an Alfred P. Sloan Foundation award for $500,000 to build a new department building.^[6] Thomas E. Kurtz had joined the department in 1956, and from the 1960s Kemeny and Kurtz agreed on the need for programming literacy among students outside the traditional STEM fields. Kemeny later noted that "Our vision was that every student on campus should have access to a computer, and any faculty member should be able to use a computer in the classroom whenever appropriate. It was as simple as that."^[7]

Kemeny and Kurtz had made two previous experiments with simplified languages,

Kemeny wrote the first version of BASIC. The acronym BASIC comes from the name of an unpublished paper by Thomas Kurtz.^[9] The new language was heavily patterned on FORTRAN II; statements were one-to-a-line, numbers were used to indicate the target of loops and branches, and many of the commands were similar or identical to Fortran. However, the syntax was changed wherever it could be improved. For instance, the difficult to remember DO loop was replaced by the much easier to remember FOR I = 1 TO 10 STEP 2, and the line number used in the DO was instead indicated by the NEXT I.^[a] Likewise, the cryptic IF statement of Fortran, whose syntax matched a particular instruction of the machine on which it was originally written, became the simpler IF I=5 THEN GOTO 100. These changes made the language much less idiosyncratic while still having an overall structure and feel similar to the original FORTRAN.^[7]

The project received a $300,000 grant from the

Wanting use of the language to become widespread, its designers made the compiler available free of charge. In the 1960s, software became a chargeable commodity; until then, it was provided without charge as a service with expensive computers, usually available only to lease. They also made it available to high schools in the Hanover, New Hampshire, area and regionally throughout New England on Teletype Model 33 and Model 35 teleprinter terminals connected to Dartmouth via dial-up phone lines, and they put considerable effort into promoting the language. In the following years, as other dialects of BASIC appeared, Kemeny and Kurtz's original BASIC dialect became known as Dartmouth BASIC.

New Hampshire recognized the accomplishment in 2019 when it erected a highway historical marker in Hanover describing the creation of "the first user-friendly programming language".^[12]

Spread on time-sharing services

The emergence of BASIC took place as part of a wider movement toward time-sharing systems. First conceptualized during the late 1950s, the idea became so dominant in the computer industry by the early 1960s that its proponents were speaking of a future in which users would "buy time on the computer much the same way that the average household buys power and water from utility companies".^[13]

General Electric, having worked on the Dartmouth project, wrote their own underlying operating system and launched an online time-sharing system known as Mark I. It featured BASIC as one of its primary selling points. Other companies in the emerging field quickly followed suit;

Although time-sharing services with BASIC were successful for a time, the widespread success predicted earlier was not to be. The emergence of minicomputers during the same period, and especially low-cost microcomputers in the mid-1970s, allowed anyone to purchase and run their own systems rather than buy online time which was typically billed at dollars per minute.[b]^[15]

Spread on minicomputers

BASIC, by its very nature of being small, was naturally suited to porting to the

A particularly important example was HP Time-Shared BASIC, which, like the original Dartmouth system, used two computers working together to implement a time-sharing system. The first, a low-end machine in the HP 2100 series, was used to control user input and save and load their programs to tape or disk. The other, a high-end version of the same underlying machine, ran the programs and generated output. For a cost of about $100,000, one could own a machine capable of running between 16 and 32 users at the same time.^[16] The system, bundled as the HP 2000, was the first mini platform to offer time-sharing and was an immediate runaway success, catapulting HP to become the third-largest vendor in the minicomputer space, behind DEC and Data General (DG).^[17]

DEC, the leader in the minicomputer space since the mid-1960s, had initially ignored BASIC. This was due to their work with RAND Corporation, who had purchased a PDP-6 to run their JOSS language, which was conceptually very similar to BASIC.^[18] This led DEC to introduce a smaller, cleaned up version of JOSS known as FOCAL, which they heavily promoted in the late 1960s. However, with timesharing systems widely offering BASIC, and all of their competition in the minicomputer space doing the same, DEC's customers were clamoring for BASIC. After management repeatedly ignored their pleas, David H. Ahl took it upon himself to buy a BASIC for the PDP-8, which was a major success in the education market. By the early 1970s, FOCAL and JOSS had been forgotten and BASIC had become almost universal in the minicomputer market.^[19] DEC would go on to introduce their updated version, BASIC-PLUS, for use on the RSTS/E time-sharing operating system.

During this period a number of simple

The introduction of the first microcomputers in the mid-1970s was the start of explosive growth for BASIC. It had the advantage that it was fairly well known to the young designers and computer hobbyists who took an interest in microcomputers, many of whom had seen BASIC on minis or mainframes. Despite Dijkstra's famous judgement in 1975, "It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration",^[22] BASIC was one of the few languages that was both high-level enough to be usable by those without training and small enough to fit into the microcomputers of the day, making it the de facto standard programming language on early microcomputers.

The first

Partially in response to Gates's letter, and partially to make an even smaller BASIC that would run usefully on 4 KB machines,

As the popularity of BASIC grew in this period, computer magazines published complete source code in BASIC for video games, utilities, and other programs. Given BASIC's straightforward nature, it was a simple matter to type in the code from the magazine and execute the program. Different magazines were published featuring programs for specific computers, though some BASIC programs were considered universal and could be used in machines running any variant of BASIC (sometimes with minor adaptations). Many books of type-in programs were also available, and in particular, Ahl published versions of the original 101 BASIC games converted into the Microsoft dialect and published it from Creative Computing as BASIC Computer Games. This book, and its sequels, provided hundreds of ready-to-go programs that could be easily converted to practically any BASIC-running platform.^[20][26][27] The book reached the stores in 1978, just as the home computer market was starting off, and it became the first million-selling computer book. Later packages, such as Learn to Program BASIC would also have gaming as an introductory focus. On the business-focused CP/M computers which soon became widespread in small business environments, Microsoft BASIC (MBASIC) was one of the leading applications.^[28]

In 1978, David Lien published the first edition of The BASIC Handbook: An Encyclopedia of the BASIC Computer Language, documenting keywords across over 78 different computers. By 1981, the second edition documented keywords from over 250 different computers, showcasing the explosive growth of the microcomputer era.^[29]

IBM PC and compatibles

When IBM was designing the

In 1991, Microsoft introduced

Mainstream support for the final version 6.0 of the original Visual Basic ended on March 31, 2005, followed by extended support in March 2008.[58] Owing to its persistent remaining popularity,^[59] third-party attempts to further support it, such as Rubberduck and ModernVB, exist.^[60] On February 2, 2017 Microsoft announced that development on VB.NET would no longer be in parallel with that of C#,^[61] and on March 11, 2020 it was announced that evolution of the VB.NET language had also concluded.^[62] Even so, the language was still supported^[63] and the third-party Mercury extension has since been produced.^[64] Meanwhile, competitors exist such as B4X,^[65] RAD Basic,^[66] twinBASIC,^[67] VisualFBEditor,^[68] InForm,^[69] Xojo,^[70] and Gambas.^[71]

Several web-based simple BASIC interpreters also now exist, including Quite Basic by Nikko Strom,[73] as well as Microsoft's Small Basic and Google's wwwBASIC.^[74] A number of compilers also exist that convert BASIC into JavaScript,^[75] such as JSBasic which re-implements Applesoft BASIC,^[76] Spider BASIC,^[77] and NS Basic.

Building from earlier efforts such as

Variants of BASIC are available on graphing and otherwise programmable calculators made by Texas Instruments (TI-BASIC), HP (HP BASIC), Casio (Casio BASIC), and others.

Windows command-line

QBasic, a version of Microsoft QuickBASIC without the linker to make EXE files, is present in the Windows NT and DOS-Windows 95 streams of operating systems and can be obtained for more recent releases like Windows 7 which do not have them. Prior to DOS 5, the Basic interpreter was GW-Basic. QuickBasic is part of a series of three languages issued by Microsoft for the home and office power user and small-scale professional development; QuickC and QuickPascal are the other two. For Windows 95 and 98, which do not have QBasic installed by default, they can be copied from the installation disc, which will have a set of directories for old and optional software; other missing commands like Exe2Bin and others are in these same directories.

Other

The various Microsoft, Lotus, and Corel office suites and related products are programmable with Visual Basic in one form or another, including

The ubiquity of BASIC interpreters on personal computers was such that textbooks once included simple "Try It In BASIC" exercises that encouraged students to experiment with mathematical and computational concepts on classroom or home computers. Popular computer magazines of the day typically included type-in programs.

Futurist and sci-fi writer

Dartmouth College celebrated the 50th anniversary of the BASIC language with a day of events[103] on April 30, 2014. A short documentary film was produced for the event.^[104]

Syntax

Typical BASIC keywords

Data manipulation

LET

assigns a value (which may be the result of an

expression

) to a variable. In most dialects of BASIC, LET is optional, and a line with no other identifiable keyword will assume the keyword to be LET.

DATA

holds a list of values which are assigned sequentially using the READ command.

READ

reads a value from a DATA statement and assigns it to a variable. An internal pointer keeps track of the last DATA element that was read and moves it one position forward with each READ. Most dialects allow multiple variables as parameters, reading several values in a single operation.

RESTORE

resets the internal pointer to the first DATA statement, allowing the program to begin READing from the first value. Many dialects allow an optional line number or ordinal value to allow the pointer to be reset to a selected location.

DIM

Sets up an array.

Program flow control

IF ... THEN ... {ELSE}

used to perform comparisons or make decisions. Early dialects only allowed a line number after the THEN, but later versions allowed any valid statement to follow. ELSE was not widely supported, especially in earlier versions.

FOR ... TO ... {STEP} ... NEXT

repeat a section of code a given number of times. A variable that acts as a counter, the "index", is available within the loop.

WHILE ... WEND and REPEAT ... UNTIL

repeat a section of code while the specified condition is true. The condition may be evaluated before each iteration of the loop, or after. Both of these commands are found mostly in later dialects.

DO ... LOOP {WHILE} or {UNTIL}

repeat a section of code indefinitely or while/until the specified condition is true. The condition may be evaluated before each iteration of the loop, or after. Similar to WHILE, these keywords are mostly found in later dialects.

GOTO

jumps to a numbered or labelled line in the program. Most dialects also allowed the form GO TO.

GOSUB ... RETURN

jumps to a numbered or labelled line, executes the code it finds there until it reaches a RETURN command, on which it jumps back to the statement following the GOSUB, either after a colon, or on the next line. This is used to implement

subroutines

.

ON ... GOTO/GOSUB

chooses where to jump based on the specified conditions. See Switch statement for other forms.

DEF FN

a pair of keywords introduced in the early 1960s to define functions. The original BASIC functions were modelled on FORTRAN single-line functions. BASIC functions were one expression with variable arguments, rather than

subroutines

, with a syntax on the model of DEF FND(x) = x*x at the beginning of a program. Function names were originally restricted to FN, plus one letter, i.e., FNA, FNB ...

Input and output

LIST

displays the full source code of the current program.

PRINT

displays a message on the screen or other output device.

INPUT

asks the user to enter the value of a variable. The statement may include a prompt message.

TAB

used with PRINT to set the position where the next character will be shown on the screen or printed on paper. AT is an alternative form.

SPC

prints out a number of space characters. Similar in concept to TAB but moves by a number of additional spaces from the current column rather than moving to a specified column.

Mathematical functions

ABS

Absolute value

ATN

Arctangent (result in radians)

COS

Cosine (argument in radians)

EXP

Exponential function

INT

Integer part (typically

floor function

)

LOG

Natural logarithm

RND

Random number generation

SIN

Sine (argument in radians)

SQR

Square root

TAN

Tangent (argument in radians)

Miscellaneous

REM

holds a programmer's comment or REMark; often used to give a title to the program and to help identify the purpose of a given section of code.

USR ("User Serviceable Routine")

transfers program control to a machine language subroutine, usually entered as an alphanumeric string or in a list of DATA statements.

CALL

alternative form of USR found in some dialects. Does not require an artificial parameter to complete the function-like syntax of USR, and has a clearly defined method of calling different routines in memory.

TRON / TROFF

turns on display of each line number as it is run ("TRace ON"). This was useful for debugging or correcting of problems in a program. TROFF turns it back off again.

ASM

some compilers such as Freebasic,^[105] Purebasic,^[106] and Powerbasic^[107] also support inline assembly language, allowing the programmer to intermix high-level and low-level code, typically prefixed with "ASM" or "!" statements.

Data types and variables

Minimal versions of BASIC had only integer variables and one- or two-letter variable names, which minimized requirements of limited and expensive memory (RAM). More powerful versions had floating-point arithmetic, and variables could be labelled with names six or more characters long. There were some problems and restrictions in early implementations; for example, Applesoft BASIC allowed variable names to be several characters long, but only the first two were significant, thus it was possible to inadvertently write a program with variables "LOSS" and "LOAN", which would be treated as being the same; assigning a value to "LOAN" would silently overwrite the value intended as "LOSS". Keywords could not be used in variables in many early BASICs; "SCORE" would be interpreted as "SC" OR "E", where OR was a keyword. String variables are usually distinguished in many microcomputer dialects by having $ suffixed to their name as a sigil, and values are often identified as strings by being delimited by "double quotation marks". Arrays in BASIC could contain integers, floating point or string variables.

Some dialects of BASIC supported matrices and matrix operations, which can be used to solve sets of simultaneous linear algebraic equations. These dialects would directly support matrix operations such as assignment, addition, multiplication (of compatible matrix types), and evaluation of a determinant. Many microcomputer BASICs did not support this data type; matrix operations were still possible, but had to be programmed explicitly on array elements.

Examples

Unstructured BASIC

New BASIC programmers on a home computer might start with a simple program, perhaps using the language's PRINT statement to display a message on the screen; a well-known and often-replicated example is Kernighan and Ritchie's "Hello, World!" program:

10 PRINT "Hello, World!"
20 END

An infinite loop could be used to fill the display with the message:

10 PRINT "Hello, World!"
20 GOTO 10

Note that the END statement is optional and has no action in most dialects of BASIC. It was not always included, as is the case in this example. This same program can be modified to print a fixed number of messages using the common FOR...NEXT statement:

10 LET N=10
20 FOR I=1 TO N
30 PRINT "Hello, World!"
40 NEXT I

Most home computers BASIC versions, such as MSX BASIC and GW-BASIC, supported simple data types, loop cycles, and arrays. The following example is written for GW-BASIC, but will work in most versions of BASIC with minimal changes:

10 INPUT "What is your name: "; U$
20 PRINT "Hello "; U$
30 INPUT "How many stars do you want: "; N
40 S$ = ""
50 FOR I = 1 TO N
60 S$ = S$ + "*"
70 NEXT I
80 PRINT S$
90 INPUT "Do you want more stars? "; A$
100 IF LEN(A$) = 0 THEN GOTO 90
110 A$ = LEFT$(A$, 1)
120 IF A$ = "Y" OR A$ = "y" THEN GOTO 30
130 PRINT "Goodbye "; U$
140 END

The resulting dialog might resemble:

What is your name: Mike
Hello Mike
How many stars do you want: 7
*******
Do you want more stars? yes
How many stars do you want: 3
***
Do you want more stars? no
Goodbye Mike

The original Dartmouth Basic was unusual in having a matrix keyword, MAT.^[g] Although not implemented by most later microprocessor derivatives, it is used in this example from the 1968 manual^[108] which averages the numbers that are input:

5 LET S = 0
10 MAT INPUT V 
20 LET N = NUM 
30 IF N = 0 THEN 99 
40 FOR I = 1 TO N 
45 LET S = S + V(I) 
50 NEXT I 
60 PRINT S/N 
70 GO TO 5 
99 END

Structured BASIC

Second-generation BASICs (for example,

REM QuickBASIC example

REM Forward declaration - allows the main code to call a
REM    subroutine that is defined later in the source code
DECLARE SUB PrintSomeStars (StarCount!)

REM Main program follows
INPUT "What is your name: ", UserName$
PRINT "Hello "; UserName$
DO
   INPUT "How many stars do you want: ", NumStars
   CALL PrintSomeStars(NumStars)
   DO
      INPUT "Do you want more stars? ", Answer$
   LOOP UNTIL Answer$ <> ""
   Answer$ = LEFT$(Answer$, 1)
LOOP WHILE UCASE$(Answer$) = "Y"
PRINT "Goodbye "; UserName$
END

REM subroutine definition
SUB PrintSomeStars (StarCount)
   REM This procedure uses a local variable called Stars$
   Stars$ = STRING$(StarCount, "*")
   PRINT Stars$
END SUB

Public Module StarsProgram
   Private Function Ask(prompt As String) As String
      Console.Write(prompt)
      Return Console.ReadLine()
   End Function

   Public Sub Main()
      Dim userName = Ask("What is your name: ")
      Console.WriteLine("Hello {0}", userName)

      Dim answer As String

      Do
         Dim numStars = CInt(Ask("How many stars do you want: "))
         Dim stars As New String("*"c, numStars)
         Console.WriteLine(stars)

         Do
            answer = Ask("Do you want more stars? ")
         Loop Until answer <> ""
      Loop While answer.StartsWith("Y", StringComparison.OrdinalIgnoreCase)

      Console.WriteLine("Goodbye {0}", userName)
   End Sub
End Module

• ANSI/ISO/IEC Standard for Minimal BASIC:
  • ANSI X3.60-1978 "For minimal BASIC"
  • ISO/IEC 6373:1984 "Data Processing—Programming Languages—Minimal BASIC"
• ECMA-55 Minimal BASIC (withdrawn, similar to ANSI X3.60-1978)
• ANSI/ISO/IEC Standard for Full BASIC:
  • ANSI X3.113-1987 "Programming Languages Full BASIC"
  • INCITS/ISO/IEC 10279-1991 (R2005) "Information Technology – Programming Languages – Full BASIC"
• ANSI/ISO/IEC Addendum Defining Modules:
  • ANSI X3.113 Interpretations-1992 "BASIC Technical Information Bulletin # 1 Interpretations of ANSI 03.113-1987"
  • ISO/IEC 10279:1991/ Amd 1:1994 "Modules and Single Character Input Enhancement"
• ECMA-116 BASIC (withdrawn, similar to ANSI X3.113-1987)

Compilers and interpreters

This section is an excerpt from List of compilers § BASIC compilers.[edit]

This list is incomplete; you can help by adding missing items. (June 2016)

Compiler	Author	Working state	Windows	Unix-like	Other OSs	License type	Standard conformance
							Minimal BASIC	Full BASIC
AppGameKit	The Game Creators	Current	Yes	Yes	No	Proprietary	?	?
BASIC-PLUS-2	Digital Equipment Corporation now HPE	Current	No	?	RSX-11M, VMS	Proprietary	?	?
B4X	Erel Uziel	Current	Yes	Yes (Android, iOS)	Yes (JVM)		No	No
BlitzMax	Blitz Research	Discontinued	Yes	Yes (Linux, macOS)	No		No	No
DarkBASIC	The Game Creators	Inactive	Yes	No	No		No	No
ECMA-55 Minimal BASIC compiler[109]	John Gatewood Ham	Current	No	Linux	No		Yes	No
FreeBASIC	FreeBASIC Development Team	Current	Yes	Yes	DOS, FreeBSD, Linux		Partial[110]	No
FutureBASIC	Brilor Software	Current	No	macOS	Classic Mac OS	Proprietary	Partial	No
Gambas	Benoît Minisini	Current	No	Yes	No		No	No
GFA BASIC	Frank Ostrowski	Abandoned	Yes	No	Amiga, Atari ST, DOS	Proprietary	No	No
Mercury	RemObjects	Current	Yes	Yes (Linux, macOS, Android, iOS)	Yes (WebAssembly)	Proprietary	No	No
PowerBASIC (formerly Turbo Basic)	PowerBASIC, Inc.	Inactive	Yes	No	DOS	Proprietary	?	?
PureBasic	Fantaisie Software	Current	Yes	Yes	Yes	Proprietary	No	No
QB64	Galleon	Current	Yes	Yes	Yes		Partial	No
QuickBASIC	Microsoft	Discontinued	No	No	DOS	Proprietary	Partial	No
Tandem BASIC	Tandem Computers	Historic	No	No	Guardian, NonStop Kernel, NonStop OS	Proprietary	No	No
True BASIC	True BASIC	Current	Yes	No	No	Proprietary	Yes	Partial[111]
VSI BASIC for OpenVMS	VMS Software, Inc.	Current	No	No	OpenVMS	Proprietary	No	No
Xojo (formerly REALbasic)	Xojo Inc. (formerly Real Software)	Current	Yes	Yes	Yes	Proprietary	No	No

This section is an excerpt from List of compilers § BASIC interpreters.[edit]

This list is incomplete; you can help by adding missing items. (December 2010)

Interpreter	Author	Windows	Unix-like	Other OSs	License type
BASIC-PLUS	Digital Equipment Corporation	No	No	RSTS/E	Proprietary
BBC BASIC (SDL 2.0)	Richard T. Russell	Yes	Yes	Web Browser
Bywater BASIC (bwBASIC)	Ted Campbell	No	Yes	?
Liberty BASIC	Shoptalk Systems	Yes	No	No	Proprietary
GW-BASIC	Microsoft	No	No	MS-DOS	Proprietary
QBasic	Microsoft	No	No	MS-DOS	Proprietary
Chipmunk Basic	Ronald H. Nicholson, Jr.	Yes	Yes	Yes	Freeware
TI Basic	Texas Instruments	No	No	TI-99/4A	Proprietary
TI Extended Basic	Texas Instruments	No	No	TI-99/4A	Proprietary
Rocky Mountain BASIC	[Trans Era]	Yes	No	HP 9000	Proprietary
Bas	Michael Haardt	No	Yes	No
Yabasic	Marc-Oliver Ihm	Yes	Yes	Haiku
SmallBASIC	SmallBASIC	Yes	Yes	Android, macOS
SuperBASIC	Jan Jones	No	No	Sinclair QL	Proprietary
thinBasic	thinBasic	Yes	No	No	Proprietary
PC-BASIC	Rob Hagemans	Yes	Yes	macOS
Level I BASIC	Steve Leininger	No	No	TRS-80 ROM	Proprietary
Level II BASIC	Microsoft	No	No	TRSDOS, NewDos/80, MultiDOS, DosPlus, LDOS	Proprietary
Level III BASIC	Microsoft	No	No	TRSDOS, NewDos/80, MultiDOS, DosPlus, LDOS	Proprietary

See also

• List of BASIC dialects

Notes

References

General references

• Sammet, Jean E. (1969). Programming languages: history and fundamentals. Englewood Cliffs, N.J.:
  OCLC 819683527
  .
• Kurtz, Thomas E. (1981). "BASIC". In Wexelblat, Richard (ed.). History of programming languages. History of Programming Languages I. New York:
  ISBN 978-0127450407
  .
• Kemeny, John G.; Kurtz, Thomas E. (1985). Back To BASIC: The History, Corruption, and Future of the Language. Addison-Wesley. p. 141.
  OCLC 11399298
  .
• Lien, David A. (1986). The Basic Handbook: Encyclopedia of the BASIC Computer Language (3rd ed.). Compusoft Publishing.
  OCLC 12548310
  .
• "Fifty Years of BASIC, the Programming Language That Made Computers Personal". Time. April 29, 2014.

External links

Wikibooks has a book on the topic of: Programming:BASIC

• BASIC at
  Curlie
• "BASIC—Beginners All-purpose Symbolic Instruction Code". The Encyclopedia of Computer Languages. Murdoch University.
• The Birth of Basic on
  YouTube
• gotBASIC.com - For all people interested in the continued usage and evolution of the BASIC programming language.
• Awesome Basic - A curated list of awesome BASIC dialects, IDEs, and tutorials.
• The Basics' page (Since 2001) - Comprehensive listing of dialects.