This program do a factorial in assembler

factorial.asm

      MOV R12, #1 //resultat
      MOV R0, #0 //iteration 
      INP R2, 2
boucle1:
      CMP R0, R2 //max
      BEQ finboucle1
      MOV R1, R0 //iteration mutliplication
      MOV R11, R12
boucle2:
      CMP R1, #0
      BEQ finboucle2
      ADD R12, R12, R11
      SUB R1, R1, #1
      B boucle2
finboucle2:
      ADD R0, R0, #1
      B boucle1
finboucle1:
      OUT R12, 4
      HALT