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

02 December 2025