Question

g) For each instruction line below, write down what the instruction does and indicate the content of all registers ra, rb, rc, rd after the instruction is executed. Mark with ? the registers whose content is unknown. The initial value of all the registers is unknown Program RB RC RA RD mov ra, AAh xor rb, rb add rb, ra shr ra asr rb [5 marks (1 per correct line)]

Answer 1

Program Μον δα, ΑΑ και This instouction moves AA hexadecimal value ento Va after this Ra= AAN Ro Ro Ro are un tenown XOR rb, rib this instruction do xor of ro with N and placed it into ro this makes 8b value ooh as XOR between Same result Oon $o Raz AAL Roz ooh Rc, RD unknown

add obra It adals content of to and Sa and placed it into ob while value of ra unchanged &b=0oht AAh = AAL So Ra=AAL Rb2 Anh Rc Rp unknown shr ra It shift Lagic right of value ra A An= 10101010 oloibidi=55h Ra=55 Rb z AAL Rc, RD Unknown EF & Carry Plag

If shifts as arithmetic right asr 8b Shift It shifts every bit to One bit right. The least significant bit is discarded. And MS B filled with the value of the previous MSB โ6 AAN lo lo lolo Wyyyyyy Toi o 10 le 25 So Raz 55 h RB z Don Rc and Ro unknown
the capital and small letter are interchangeable

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