Refactor code.

src/SUDOKU.ASM

@@ -0,0 +1,34 @@
+;-*-MIDAS-*-
+		TITLE    SUDOKU SOLVER
+
+;Define the accumulators
+A=1                                   ;The primary accumulator.
+B=2                                   ;Other ACs.
+C=3
+X=4                                   ; X and Y are used for indexing
+Y=5                                   ; loops etc.
+
+;Set up the stack
+P=17
+PDLLEN==20                             ;Size of the stack.
+PDL BLOCK PDLLEN                       ;Reserve the stack memory.
+
+BPTR==440700                           ;Define a byte pointer.
+CHTTYO==1                              ;Define a channel for TTY output.
+
+START:    MOVE  P,[-PDLLEN,,PDL-1]     ;Initialize the stack.
+          .OPEN CHTTYO,[.UAO,,'TTY]    ;Open the output channel.
+           .LOSE %LSFIL                ;Gobble up error messages.
+          MOVE  A,[BPTR,,HELLO]        ;Load A with a byte pointer to HELLO.
+          JRST  DONE                   ;Jump to the end of the program.
+OUTSTR:   HRLI  A,BTPR                 ;Ensure, A is a byte pointer.
+OUT:      ILDB  B,A                    ;Load the next byte from A.
+          JUMPE B,OUTEX                ;Exit the routine, if all bytes are done.
+          .IOT  CHTTYO,B               ;Print a character.
+		  JRST  OUT                    ;Jump back to print the next character.
+OUTEX:    .IOT  CHTTYO,[^M]            ;Print carriage return and
+          .IOT  CHTTYO,[^J]            ;newline characters.
+          POPJ  P,                     ;Return from the subroutine.
+DONE:                                  ;Exit point for the program.
+HELLO:    ASCIZ  /HELLO WORLD/         ;Define example string.  
+END       START

src/SUDOKU.MAC

@@ -1,33 +0,0 @@
-;-*-MIDAS-*-
-		TITLE    SUDOKU SOLVER
-P=17                                   ;Defines AC 17 as the stack pointer.
-
-A=1                                    ;Define two accumulators
-B=2                                    ;A and B
-CHTTYO==1                              ;Output channel number
-
-PDLLEN==100                            ;Length of push down stack
-PDL:    BLOCK PDLLEN                   ;Storage for push down stack
-
-START:  MOVE P,[-PDLLEN,,PDL-1]        ;Initialize the stack
-        .CALL [SETZ ? SIXBIT/OPEN/     ;Open the TTY channels
-		    [.UAI,,CHTTYO] ? [SIXBIT/TTY/] ((SETZ))]
-		 .LOSE %LSFIL
-
-
-L:      MOVE A, [440700,,HELLO]         ;Load the address of the string into A
-        PUSHJ P, OUTSTR                ;Print the string.
-		JRST L                         ;Keep looping
-
-;Subroutine to output the ASCIZ which starts in the word
-;whose address is in A. Clobbers A.
-OUTSTR: HRLI A, 440700                ;Make A into a byte pointer to fetch a string
-OUTST1: ILDB B, A                     ;Fetch the next character of string into B
-        JUMPE B, CPOPJ                ;If it is the terminator, return
-	    .IOT CHTTYO,B                 ;Else output the character
-		JRST OUTST1                   ;and loop around.
-
-CPOPJ:  POPJ P,                       ;Return
-
-HELLO:  ASCIZ /HELLO WORLD/
-        END    START