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Paradigms | Multi-paradigm: procedural, imperative, structured |
---|---|
Family | ALGOL |
Developer | Data General |
First appeared | 1978 |
Platform | Nova, Eclipse, Eclipse/MV |
OS | RDOS, AOS, AOS/VS |
Influenced by | |
ALGOL 60 |
DG/L is a programming language developed by Data General Corp for the Nova, Eclipse, and Eclipse/MV families of minicomputers in the 1970s and early 1980s.
There were two separate versions:
The language itself was an extended version of Algol 60. It supported Integers, Single and Double precision floating point and complex numbers, and both fixed and arbitrary precision strings. It also supported full arbitrary precision binary-coded decimal (BCD) arithmetic on strings. It had many convenient program control flow features, but being designed in the mid 70s, lacked user defined data structures.
DG/L had a substantial runtime library for its day, and was used for systems programming both within and outside of Data General.
Originally called Algol/5, the product renamed DG/L shortly before the first commercial release in 1978. Officially, the name is meaningless but it was apparently supposed to imply "Data General Language". After the first commercial release, targeting 16-bit Eclipse and Nova, several subsequent updates and major versions were released, approximately one a year.
Appendix A of Data General's 1982 revision of its DG/L Language Reference Manual, 093-00229-01 describes DG/L as based on the ALGOL 60 programming language, but gives "data types, operations and statements that ALGOL 60 lacks". Specific differences are:
Algol 60 feature | As described in Algol 60 report [1] paragraph | DG/ notes |
---|---|---|
Call by name | para. 4.7.3.2 | DG/L allows procedure parameters as type PROCEDURE, allowing procedures to be passed by name to other procedures. |
Nested quotation marks in literals | 2.6.1 and 2.4.1 | |
No limit on length of identifiers | DG/L identifier names need to be unique within the first 32 characters | |
Two division operators | 3.3.4.2 | DG/L uses "/" for both real and integer division; an integer divided by another integer implies integer division (e.g. 1/4 is 0) unless the compiler's global /R switch is used |
Notation of 10 <integer> | 2.5.1 | DG/L uses E <integer> (or D <integer> for double precision) for "scientific" notation to show powers of ten |
A program consisting only of a <compound statement> | 4.1.1 | |
Non-ASCII characters ⋀,⋁,¬,⊃,≡,≤,≥,≠ as Boolean operators | 3.4.6.1 | DG/L allows instead: AND, OR, NOT, IMP, EQV, <= (or =<),>= (or =>), and <> (or ><) as well as XOR |
Including non-Algol code within Algol procedures | 4.7.8 | Apart from the FORTRAN 5 math library, documentation for external procedures assumes only other DG/L procedures will be linked in. |
Some of the extensions to the Algol 60 standard introduced in DG/L or carried over from Data General's previous Algol implementation of 1971:
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