Waduzitdo

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Waduzitdo (What does it do?), originally spelled in all caps (WADUZITDO) as many programming languages were at the time, is a non-Turing complete derivative of PILOT. It was created by BYTE Magazine contributor Larry Kheriaty in the late 1970s as a way to put together quick and dirty demonstrations for friends not familiar with the functions of computers, and is most useful for simple question-and-answer quiz and game programs.

Commands

The one-letter commands are as follows, and the colons are part of the commands:

• T: Output text; this command is immediately followed by the text, no quotation marks.
• A: Accept one character of input. This command appears on a line by itself and does not have a value after it.
• M: Character matching. Often put before a command with a branch flag, so M:x means "if the x key is pressed".
• Y is put on the same line, with no spaces, immediately before another command, usually a text output or jump, to perform that command only when the previous character match is true, so often you will see YT:insert text here.
• N is put on the same line, with no spaces, immediately before another command, usually a text output or jump, to perform that command only when the previous character match is false, so often you will see NT:insert text here.
• * is put before another command, usually a text output, to indicate that it is a command that can be jumped to, also known as a section marker or program marker.
• J: Followed by a number, this command jumps that many * section markers, so J:6 jumps to the sixth section marker from the current point. Waduzitdo cannot jump back.
• S: This command stops execution.

User:Star651 has devised a mnemonic for remembering the list of commands; NASTY star MJ, where the star is a way of pronouncing the * symbol. The mnemonic can also be turned into a sentence, like "MJ is a nasty star", to make it even easier to remember.

Computational class

Waduzitdo is capable of implementing all deterministic finite-state transducers, but cannot implement any program other than a finite-state transducer – because it can branch based on input and has fully arbitrary jumps, it can implement a deterministic finite-state transducer pretty much directly, but has no operations that would allow for more power.

Examples

Hello, World!

T:Hello, World!
S:

Nim Game

T:Nim for Waduzitdo, exactly how it appeared in 1978! Except for this line!
T:LET'S PLAY NIM WITH 7 PEBBLES.
T:WE TAKE TURNS TAKING 1,2 OR 3.
T:THE LAST ONE TO TAKE ONE LOSES.
T:THERE ARE 7, HOW MANY ?
A:
M:1
YJ:1
M:2
YJ:2
M:3
YJ:6
T:YOU CAN TAKE ONLY 1,2, OR 3.
J:0
*T:THAT LEAVES 6, I TAKE 1 LEAVING 5.
T:HOW MANY ?
A:
M:1
YJ:5
M:2
YJ:4
M:3
YJ:3
T:YOU MUST TAKE 1,2 OR 3.
J:0
*T:THAT LEAVES 5, I TAKE 1 LEAVING 4.
T:HOW MANY ?
A:
M:1
YJ:3
M:2
YJ:2
M:3
YJ:1
T:YOU MUST TAKE 1,2 OR 3 ONLY.
J:0
*T:THAT LEAVES THE LAST ONE.
T:I TAKE IT ... YOU WIN!
J:5
*T:THAT LEAVES 2, I TAKE 1 LEAVING 1.
J:3
*T:THAT LEAVES 3, I TAKE 2 LEAVING 1.
J:2
*T:THAT LEAVES 4, I TAKE 3 LEAVING 1.
*T:HOW MANY ?
A:
M:1
NT:YOU HAVE NO CHOICE BUT TO TAKE 1.
NT:HOW MANY ?
NJ:0
T:YOU JUST TOOK THE LAST ONE ... I WIN.
*T:TO PLAY AGAIN TYPE THE DOLLAR SIGN.
S:

See also

• EWaduzitdo, a 2024 language that is a compatible superset of Waduzitdo with variable and math features, though Turing completeness is still uncertain.

External resources

• Web-based interpreter, written in JavaScript by Hans Franke in 2006 and based on the 1978 specification.
• WADUZITDO: How To Write a Language in 256 Words or Less. Original BYTE magazine article by Larry Kheriaty from September 1978 (vol. 3, number 9, p.166)
• WADUZITDO 2001 (from the Wayback Machine; retrieved on 23 October 2009), an update to the 1978 spec, by Brian Connors.
• KIM-1 compatible version on Github.
• Python interpreter that is slightly easier to use than the web-based one, Created by Petar Jovanović in May 2024 as mostly a line-by-line Python translation of the web version.