; 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