DapAn_De Thi Cuoi Ky HK2 2013-2014
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Cu 1 (1,5 im)
Sinh vin mun thc hin lnh if, phi bit tn dng cc lnh r nhnh c hc (hoc beq hoc bne)
slt $t0, $s0, $s1 // if (i
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Cu 4 (2 im)
a. Khng forwarding (1 im)
lw $s1, 4($s2)
nop
nop
add $s4, $s3, $s1
nop
nop
and $s5, $s4, $s1
Hnh nh cc chu k pipeline khi on lnh trn thc thi:
lw $s1, 4($s2) IF ID EX MEM WB
nop
nop
add $s4, $s3, $s1 IF ID EX MEM WB
nop
nop
and $s5, $s4, $s1 IF ID EX MEM WB
b. C forwarding (1 im)
lw $s1, 4($s2)
nop
add $s4, $s3, $s1
and $s5, $s4, $s1
Hnh nh cc chu k pipeline khi on lnh trn thc thi:
lw $s1, 4($s2) IF ID EX MEM WB
nop
add $s4, $s3, $s1 IF ID EX MEM WB
and $s5, $s4, $s1 IF ID EX MEM WB
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Cu 5 (3 im)
addi Rt, Rs, Imm ( ngha Rt = Rs + Imm)
a) Tt c cc block u c s dng ngoi tr Data memory (0,5)
b) Gi tr ca cc tn hiu iu khin? (0,5)
RegDst Branch MemRead MemtoReg ALUOp MemWrite ALUSrc RegWrite
0 0 0 0 00 0 1 1
c) (0,5)
- Nhng block c cho d liu output nhng d liu ny khng s dng: B cng th 2 (b cng m c mt input qua khi shift_left_2 trc khi vo b cng)
- Nhng block khng cho output: Data memory
d) (0,5)
Thi gian tr ln nht cho lnh trn = I-Mem + Mux + Regs + Mux + ALU + Mux + Regs
= 400 + 30 + 200 + 30 + 120 + 30 + 200 = 1010 ps
e) addi Rt, Rs, Rx, Imm ( ngha Rt = Rs + Rx + Imm) (1)
- Vic cng thc hin trn 3 ton hng nn: hoc s dng thm 1 ALU hoc chnh sa li ALU ang c bng cch a thm mt input th 3 vo (0.5 im)
- Trng opcode (6 bits), 3 thanh ghi (mi thanh ghi 5 bits) s bits trng cn li trong format lnh trn l 11 bits. Vy trng Imm c th s dng bao nhiu bits ty vo thit k, nhng khng qu 11 bits ny. Gi n l s bits cho trng Imm Khi Sign-extend hin ti l m rng c du t s tc thi 16 bits thnh 32 bits; v vy hoc s dng thm mt khi Sign-extend vi input l n bits hoc chnh sa khi Sign-extend sao cho c th nhn c input 16 bits v n bits
ALU cn thc hin thao tc cng.
Gi tr m ALUOp nn nhn y ph thuc vo thit k
ca khi ALU Control (sao cho m bo kt qu ca ALU
Control ra tng ng vi thao tc cng)
Nu theo thit k trong sch tham kho chnh th ALUOp
c th nhn 2 gi tr 00 ging nh lw hoc sw cho lnh addi
ny.