Editing BASIC Programming

{{About|the Atari 2600 cartridge|programming in other BASIC dialects|BASIC|other uses|Basic programming (disambiguation){{!}}Basic programming}}
{{Use dmy dates|date=July 2017}}
{{more citations needed|date=October 2017}}

{{Infobox video game
|title        = BASIC Programming
|image        = BASIC Programming Cover Art.jpg
|developer    = [[Atari, Inc.]]
|publisher    = Atari, Inc.
|designer     = [[Warren Robinett]]<ref>[https://dadgum.com/halcyon/BOOK/ROBINETT.HTM Interview:Warren Robinett], By James Hague, ''Halcyon Days'', "How long did it take to write?...I had ''Adventure'' sort of done in the fall of 1978, but I wasn't satisfied. I sort of put it on the shelf for the next six months while I did the ''BASIC Programming'' cartridge, and finished them both simultaneously, in June 1979."</ref>
|released     = 1979
|platforms    = [[Atari 2600]]
}}

'''''BASIC Programming''''' is an Atari Video Computer System (later called the [[Atari 2600]]) cartridge that teaches simple computer programming using a dialect of [[BASIC]]. Written by [[Warren Robinett]] and released by [[Atari, Inc.]] in 1979, this [[BASIC interpreter]] is one of a few non-game cartridges for the console. The Atari VCS's [[Random-access memory|RAM]] size of 128 bytes restricts the possibilities for writing programs.

==Details==
[[Image:Basicprogramming.png|thumb|upright=2|Main display]]

The ''BASIC Programming'' display is divided into six regions:

* '''Program''' is where instructions are typed. It has a maximum of eleven lines of code.
* '''[[Call stack|Stack]]''' shows temporary results of what the program does. 
* '''[[Variable (computer science)|Variables]]''' stores the values of any variables that the program is using. 
* '''Output''' displays any output values that the program creates. 
* '''Status''' shows the amount of available memory remaining.
* '''Graphics''' contains two colored squares that can be manipulated by the program.

Input is given through two Atari keypad controllers, which came with special overlays to show how to type the different commands and letters.<ref>[https://atariage.com/controller_page.html?ControllerID=4&SystemID=2600 Controllers - Atari Keypad], {{Webarchive|url=https://web.archive.org/web/20150615042830/https://atariage.com/controller_page.html?ControllerID=4&SystemID=2600 |date=15 June 2015 }} Atari KeypadSystem: Atari 2600, Model Number: CX50, ''Sold in pairs, functionally identical to the Kid's Controller and the Video Touch Pad. Included overlays with commands, meant to be used with Basic Programming.''</ref>  Programs are restricted to 64 characters in size and normally 9 lines of code, limiting the programs that can be written (users can disable all windows except Program and keep selecting "New Line" until 11 lines of code are present).

===Language features===

VCS BASIC supports the following keywords:<ref>{{cite book|title=BASIC Programming: Atari Game Program Instructions|date=1979|publisher=Atari, Inc.|location=Sunnyvale, CA}}</ref>
* Statements: <code>Print</code>
* Structure: <code>Goto</code>, <code>If-Then-Else</code>
* Graphics: <code>Clear</code>
* Functions: <code>Hit</code>, <code>Key</code>
* Math: <code>+ - × ÷ Mod</code>
* Relational operators: <code>< > =</code>

Unlike most BASIC implementations of the time:
* VCS BASIC uses ← instead of = for assignment; e.g., <code>A←A+1</code>.
* Statements can be strung together on a line without a delimiter; e.g., <code>Note←APrintA</code>.
* An <code>If</code> statement can be used as a function, returning a value: <code>{{codett|2=cbmbas|Ver1←Ver1+IfVer1}}[[Modulo operation|Mod]]2{{codett|2=cbmbas|Then8}}{{codett|2=monkey|Else}}92</code>
* <code>If</code> statements can take an <code>Else</code> clause.

Special variable names:
* <code>Note</code> sounds a musical note, assigned numbers from 0 to 7
** Numbers assigned to <code>Note</code> are implicitly assigned modulus 8, thus 8 becomes 0, 9 becomes 1, etc.
* <code>Hor1</code>, <code>Hor2</code> - the horizontal coordinate of one of two squares
* <code>Ver1</code>, <code>Ver2</code> - the vertical coordinate of one of two squares

The language supports 26 unsigned integer variables A to Z. VCS BASIC supports integers from 0 to 99. Math operations wrap, so 99+1 becomes 0, 99+2 becomes 1, etc.

====Sample code====
The following example of a ''[[Pong]]'' game is provided.
{{pre|
1 Hor2←2+Key
2 {{codett|2=cbmbas|IfVer1>90ThenVer1←88}}
3 {{codett|2=cbmbas|IfHit}}{{codett|2=cbmbas|ThenVer1←9}}
4 {{codett|2=cbmbas|Ver1←Ver1+IfVer1}}[[Modulo operation|Mod]]2{{codett|2=cbmbas|Then8}}{{codett|2=monkey|Else}}92
5 Hor1←Hor1+7
6 {{codett|2=cbmbas|Goto1}}
}}

==See also==
{{Portal|Video games}}
*[[List of Atari 2600 games]]
* [[CompuMate|Spectravideo CompuMate]]
* [[Family BASIC]]

==References==
{{reflist}}

==External links==
* {{atarimania|id=20194}}
* {{webarchive |url=https://web.archive.org/web/20040123023347/http://www.mindspring.com/~sidartha/Basic%20and%20Compumate%20Programming.htm |date=January 23, 2004 |title=Compumate FAQ:BASIC PROGRAMME EXAMPLES FOR ATARI 2600 (BASIC PROGRAMMING & CompuMate)}}

{{BASIC}}

[[Category:1979 software]]
[[Category:Atari 2600]]
[[Category:BASIC interpreters]]
[[Category:BASIC programming language family]]
[[Category:Discontinued BASICs]]
[[Category:Video game development software]]