; sub.asm
; subtract two 4bit numbers on the Intel 4004
   FIM R0R1, 0x35 ; initialize R0=5 & R1=3
   FIM R2R3, 0    ; clear result pair
   LD R0     	  ; load R0 into accumulator
   SUB R1         ; subtract second number
   XCH R1         ; and store in R1
done:
   JUN done       ; end