Category:RTL/2

From Rosetta Code
This page uses content from Wikipedia. The original article was at RTL/2. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)
Language
RTL/2
This programming language may be used to instruct a computer to perform a task.
Parameter passing methods: By reference, By value
Type safety: Safe
Type strength: Weak
Type compatibility: Structural
Type expression: Explicit
Type checking: Dynamic, Static
See Also:
Listed below are all of the tasks on Rosetta Code which have been solved using RTL/2.

RTL/2 was a high-level programming language developed at Imperial Chemical Industries Ltd by J.G.P. Barnes. It was originally used internally within ICI but was distributed by SPL International in 1974[1] It was designed for use in real-time computing (hence the acronym RTL = real-time language). Based on concepts from Algol 68, it was intended to be a small, simple language.[2][3] RTL/2 was standardised in 1980 by the British Standards Institution[4].

RTL/2 was a weakly typed language with separate compilation. The compilation units contained one or more items known as "bricks", i.e.:

  • procedure bricks,
  • data bricks,
  • stack bricks.

A procedure brick was a procedure, which may or may not return a (scalar) value, have (scalar) parameters, or have local (scalar) variables. The entry mechanism and implementation of local variables was re-entrant. Non-scalar data could only be accessed via reference (so-called REF variables were considered scalar).

A data brick was a named static collection of scalars, arrays and records. Programmers had to implement memory management themselves (there was no heap or garbage collection).

A stack brick was an area of storage reserved for running all the procedures of a single process and contained the call stack, local variables and other housekeeping items. The extent to which stack bricks were actually used varied depending upon the host environment in which RTL/2 programs actually ran.

Access to the host environment of an RTL/2 program was provided via special procedure and data bricks called SVC procedures and SVC data. These were accessible in RTL/2 but implemented in some other language in the host environment.

Dropping into Assembler

RTL/2 compiles to assembly language and provides the CODE statement to permit assembly language to be inserted directly into RTL/2 programs. This is only available when compiled with a systems programming option (CN:F)

The Code statement takes two operands: the number of bytes used by the code insert and the number of bytes of stack used.

Within code statements two trip characters are used to access RTL/2 variables. These vary from operating system to operating system. On PDP-11 and VAX/VMS the trip characters are '*' and '/'

While the specifics varied by operating system the following is an example of a code insert on VAX/VMS:

CODE 6,0;
JMP CODE_ENT ; This code insert can be set to a fixed length as it jumps to a new psect.
; this technique is especially useful on systems such as VMS where the length
; of instructions is variable
.SAVE_PSECT  ; Save current program section
.PSECT ASMB_CODE,EXE,NOWRT,LONG
CODE_ENT:
MOVL *PARAM1(AP),*COUNTER/MYDATA
JMP CODE_EX
.RESTORE_PSECT
CODE_EX:
*RTL

This code insert moves the value of a variable passed into the RTL/2 procedure into a variable called COUNTER in a data brick called MYDATA.

Reserved Words

ABS AND ARRAY BIN BLOCK BY BYTE CODE DATA DO ELSE ELSEIF END ENDBLOCK ENDDATA ENDPROC ENT EXT FOR FRAC GOTO HEX IF INT LABEL LAND LENGTH LET LOR MOD NEV NOT OCT OF OPTION OR PROC REAL REF REP RETURN RTL SHA SHL SLA SLL SRA SRL STACK SVC SWITCH THEN TITLE TO VAL WHILE

References

SPL Documentation

SPL published a range of documentation for RTL/2. Each of these documents had a reference number assigned. The following is an incomplete list.

RTL/2 Ref 1  - Language Specification
RTL/2 Ref 2  - Introduction to RTL/2
RTL/2 Ref 3  - RTL/2 Training Manual
RTL/2 Ref 4  - System Standards
RTL/2 Ref 5  - Stream I/O
RTL/2 Ref 18 - Hints on writing RTL/2 Programs
RTL/2 Ref 26 - Language Reference Card
RTL/2 Ref 39 - Run time environment on the PDP-11
RTL/2 Ref 63 - User Manual for the PDP-11 under RSX-11M
RTL/2 Ref 107- VAX/VMS RTL/2 User Manual
RTL/2 REF 130- The RTL/2 32 bit run time environment on the VAX
  1. Barnes J.G.P., The Standardisation of RTL/2, Software Practice and Experience, Volume 10 Issue 9, pp 707 - 719, Wyley, September 1980
  2. RTL/2 Language Specification
  3. http://hopl.murdoch.edu.au/showlanguage2.prx?exp=596#_jmp0_
  4. http://shop.bsigroup.com/en/ProductDetail/?pid=000000000000133906

Code Specimen


This page is a stub. It needs more information! You can help Rosetta Code by filling it in!

Subcategories

This category has the following 3 subcategories, out of 3 total.

Pages in category "RTL/2"

This category contains only the following page.