MACRO-11

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MACRO-11 is an assembly language with macro facilities for PDP-11 minicomputers from Digital Equipment Corporation (DEC). It is the successor to PAL-11 (Program Assembler Loader), an earlier version of the PDP-11 assembly language without macro facilities.

The MACRO-11 assembly language was designed for the PDP-11 minicomputer family. It was supported on all DEC PDP-11 operating systems. PDP-11 Unix systems also include an assembler (called "as"), structurally similar to MACRO-11 but with different syntax and fewer features.

[edit] Programming example

A complete "Hello, world!" program in PDP-11 macro assembler, to run under RT-11:

.TITLE  HELLO WORLD
        .MCALL  .TTYOUT,.EXIT
HELLO:: MOV     #MSG,R1 ;STARTING ADDRESS OF STRING
1$:     MOVB    (R1)+,R0 ;FETCH NEXT CHARACTER
        BEQ     DONE    ;IF ZERO, EXIT LOOP
        .TTYOUT         ;OTHERWISE PRINT IT
        BR      1$      ;REPEAT LOOP
DONE:   .EXIT
 
MSG:    .ASCIZ /Hello, world!/
        .END    HELLO

If this file is HELLO.MAC, the RT-11 commands to assemble, link and run (with console output shown) are as follows:

.MACRO HELLO
ERRORS DETECTED:  0
 
.LINK HELLO
 
.R HELLO
Hello, world!
.

(The RT-11 command prompt is ".")

For a more complicated example of MACRO-11 code, two examples chosen at random are Kevin Murrell's KPUN.MAC, or Farba Research's JULIAN routine. More extensive libraries of PDP-11 code can be found in the Metalab freeware and Trailing Edge archives.^[1]^[2]