| Paradigms | procedural |
|---|---|
| Designed by | John G. Kemeny |
| Developer | Sidney Marshall |
| First appeared | 1962; 62 years ago (1962) |
| Implementation language | Assembly |
| Platform | LGP-30 |
| Influenced by | |
| DARSIMCO, DART, Dartmouth ALGOL 30, Fortran | |
| Influenced | |
| Dartmouth BASIC | |
DOPE, short for Dartmouth Oversimplified Programming Experiment, was a simple programming language designed by John Kemény in 1962 to offer students a transition from flow-charting to programming the LGP-30. Lessons learned from implementing DOPE were subsequently applied to the invention and development of BASIC.
Description
Each statement was designed to correspond to a flowchart operation and consisted of a numeric line number, an operation, and the required operands:
7 + A B C 10 SIN X Z
The final variable specified the destination for the computation. The above program corresponds in functionality to the later BASIC program:
7 LET C=A+B 10 LET Z=SIN(X)
DOPE might be the first programming language to require every statement to have a line number, predating JOSS and BASIC.
The language was case insensitive.
Variable names were a single letter A to Z, or a letter followed by a digit (A0 to Z9). As with Fortran, different letters represented different variable types. Variables starting with letters A to D were floating point, as were variables from I to Z; variables E, F, G, and H each were defined as vectors with components from 1 to 16.
| Operation | Function | Number of operands |
|---|---|---|
| A | Ask (prompt for input) | 2 |
| C | Arithmetic IF | 4 |
| E | End loop | (Unknown) |
| J | Input into variable | 1 |
| N | Print a newline | (Unknown) |
| P | Print a variable | 1 |
| T | Jump | 1 |
| Z | For loop | (Unknown) |
| + | Addition | 3 |
| - | Subtraction | 3 |
| * | Multiplication | 3 |
| / | Division | 3 |
| EXP | E to the power | 2 |
| LOG | Logarithm | 2 |
| SIN | Sine | 2 |
| SQR | Square root | 2 |
The language was used by only one freshman computing class. Kemeny collaborated with high school student Sidney Marshall (taking freshman calculus) to develop the language.
Legacy
According to Thomas Kurtz, a co-inventor of BASIC, "Though not a success in itself, DOPE presaged BASIC. DOPE provided default vectors, default printing formats, and general input formats. Line numbers doubled as jump targets."
The language had a number of other features and innovations that were carried over into BASIC:
- Variable names were either a letter or a letter followed by a digit
- Arrays (vectors) did not have to be declared and had a default size (16 instead of 10)
- Every line required a numeric label*
- Lines were sorted in numeric order*
- Every line begins with a keyword*
- Function names were three letters long*
- The only loop construct was a for-loop
*Unlike either Fortran or Algol 60.
See also
- DARSIMCO, 'Dartmouth Simplified Code', a 1956 assembler macro language
- Dartmouth ALGOL 30, a compiler developed by Dartmouth for the LGP-30
References
- Kurtz, Thomas (1981). "BASIC". History of programming languages. History of programming languages I. ACM. pp. 517-518 517–518. doi:10.1145/800025.1198404. ISBN 0-12-745040-8.
- Williams, Michael (November 1, 1985). A History of Computing Technology (1st ed.). Prentice-Hall. p. 432. ISBN 0133899179.
- Application to the National Science Foundation, Kurtz, Rieser, and Meck, cited in Rankin, pages 20-21
- Kemeny, John G.; Kurtz, Thomas E. (1985). Back To BASIC: The History, Corruption, and Future of the Language. Addison-Wesley Publishing Company, Inc. 141 pp. ISBN 0-201-13433-0
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