- Tiny BASIC
Tiny BASIC is a dialect of the
BASIC programming language that can fit into as little as 2 or 3 KB of memory. This small size made it invaluable in the early days of s (the mid-1970s), when typical memory size was 4–8 KB.History
The language was first developed solely as a standards document, written primarily by
Dennis Allison , a member of the Computer Science faculty atStanford University . He was urged to create the standard byBob Albrecht of theHomebrew Computer Club . He had seen BASIC onminicomputer s and felt it would be the perfect match for new machines like the MITS Altair 8800, which had been released in January 1975.Bob and Dennis published the design document in the newsletter of the
People's Computer Company . In December 1975, Dick Whipple and John Arnold created an interpreter for the language that required only 3K of RAM. Bob and Dennis decided to publish this version and corrections to the original design documents in a newsletter dedicated to Tiny BASIC, which they called "Dr. Dobb's Journal of Tiny BASIC Calisthenics and Orthodontia". The newsletter's title was changed to "Dr. Dobb's Journal of Computer Calisthenics & Orthodontia" for the second issue. In the 1976 issues several versions of Tiny BASIC, including design descriptions and full source code, were published (as of 2005 the newsletter still exists, in the form of professional programmers' magazine "Dr. Dobb's Journal ").Tiny BASIC grammar
The grammar is listed below in
Backus-Naur form . In the listing, an asterisk ("*") denotes zero or more of the object to its left — except for the first asterisk in the definition of "term", which is the multiplication operator; parentheses group objects; and an epsilon ("ε") signifies the empty set. As is common in computer language grammar notation, the vertical bar ("|") distinguishes alternatives, as does their being listed on separate lines. The symbol "CR" denotes acarriage return (usually generated by a keyboard's "Enter" key).line ::= number statement CR | statement CR statement ::= PRINT expr-list IF expression relop expression THEN statement GOTO expression INPUT var-list LET var = expression GOSUB expression RETURN CLEAR LIST RUN END expr-list ::= (string|expression) (, (string|expression)* ) var-list ::= var (, var)* expression ::= (+|-|ε) term ((+|-) term)* term ::= factor ((*|/) factor)* factor ::= var | number | (expression) var ::= A | B | C .... | Y | Z number ::= digit digit* digit ::= 0 | 1 | 2 | 3 | ... | 8 | 9 relop ::= < (>|=|ε) | > (<|=|ε) | = A BREAK from the console will interrupt execution of the programSource: "Dr. Dobb's Journal of Computer Calisthenics & Orthodontia", Volume 1, Number 1, 1976, p.9.
Implementation in interpreted language
For the implementation, an
interpreted language (IL) is used. An interpreter written in IL interprets a line of Tiny Basic code and executes it. The IL is run on anabstract machine , which interprets IL code. The idea to use an interpreted language goes back to Val Schorre (withMETA II , 1964) and Glennie (Syntax Machine). See alsovirtual machine , CLI.The following table gives a partial list of the commands of the "interpreted language" in which the Tiny BASIC interpreter is written. The length of the whole interpreter program is only 120 IL operations. Thus the choice of an interpretive approach economized on memory space and implementation effort, although the BASIC programs run thereon were executed somewhat slowly. The CRLF in the last line symbolizes a carriage return followed by a
line feed .
Source: "Dr. Dobb's Journal", Volume 1, Number 1, 1976, p.12.TST "lbl", "string" If "string" matches the BASIC line, advance cursor over "string" and execute the next IL instruction; if the test fails, execute the IL instruction at the label "lbl" CALL "lbl" Execute the IL subroutine starting at "lbl"; save the IL address following the CALL on the control stack RTN Return to the IL location specified at the top of the control stack DONE Report a syntax error if after deleting leading blanks the cursor is not positioned to reach a carriage return JUMP "lbl" Continue execution of the IL at the label specified PRS Print characters from the BASIC text up to but not including the closing quotation mark PRN Print number obtained by popping the top of the expression stack SPC Insert spaces to move the print head to next zone NLINE Output a CRLF to the printer ee also
*
Palo Alto Tiny BASIC , byLi-Chen Wang External links
* [http://www.IttyBittyComputers.com/IttyBitty/TinyBasic/TBuserMan.htm "Tiny Basic User Manual"] and [http://www.IttyBittyComputers.com/IttyBitty/TinyBasic/TBEK.txt "Experimenter's Kit"] – by [http://www.IttyBittyComputers.com/IttyBitty/TinyBasic/index.htm Tom Pittman]
* [http://www.swtpc.com/mholley/BASIC_2/Uiterwyk.htm Robert Uiterwyk's MICRO BASIC] – A MC6800 tiny BASIC later sold with theSWTPC 6800 computer
* [http://www.signiform.com/erik/pubs/minol.htm MINOL] – Eri k Mueller's MINOL – Tiny BASIC with strings for Intel 8080
* [http://www.multicians.org/raf-tbl-definition.html TBL] – A similar IL to Tiny BASIC's, used in the first successful compilers for PL/I, Fortran, etc, on limited memoryminicomputer s
* [http://members.shaw.ca/gbrandly/68ktinyb.html M68000 Tiny BASIC] – Based onLi-Chen Wang 'sPalo Alto Tiny BASIC , and published in the 100th edition of "Dr. Dobb's"
* [http://smallbasic.sourceforge.net/sb/tiny.txt Tiny BASIC] – An implementation written inSmallBASIC
* [http://www.aldweb.com/articles.php?lng=en&pg=7407 tinyBasic] – An implementation written in [http://www.aldweb.com/articles.php?lng=en&pg=5350 iziBasic]
* [http://www.runbasic.com/?_page=tinybasic.bas Tiny BASIC] – A live web version, ported to Run BASIC from iziBasic
* [http://www.thisiscool.com/tinybasic.htm TinyBasic] – A port of [http://www.ittybittycomputers.com/IttyBitty/TinyBasic/TinyBasic.c Tom Pittman's TinyBasic C interpreter] to Java, C# and Adobe Flex. Includes live web versions.
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