Patterns

For loop

This is a simple program in SIC/XE that takes each word in ALPHA, adds the corresponding word in BETA, and stores the sum in GAMMA. It does this by adding 3 (bytes per word) to the index register X and comparing the value of X to the value in register T, which contains the length of ALPHA, BETA, and GAMMA.

                       .For loop in SIC/XE
       LDS    #3       .Initialize Register S to 3
       LDT    #300     .Initialize Register T to 300
       LDX    #0       .Initialize Index Register to 0
ADDLP  LDA    ALPHA,X  .Load Word from ALPHA into Register A
       ADD    BETA,X   .Add Word From BETA
       STA    GAMMA,X  .Store the Result in a work in GAMMA
       ADDR   S,X      .ADD 3 to INDEX value
       COMPR  X,T      .Compare new INDEX value to 300
       JLT    ADDLP    .Loop if INDEX value is less than 300
ALPHA  RESW   100
BETA   RESW   100
GAMMA  RESW   100