Exercises

Lesson 3: The Control Unit

Computer Structure andOrganization

Graduate in Computer SciencesGraduate in Computer Engineering

Academic course: 2012-2013

Lesson 3: Page: 2 / 12

The Control Unit

1. Lets be an elemental computer with the following elements:

• A 16 operations ALU with two multiplexor attached to their inputs.

• Accumulator register to store temporal values.

• A 32 registers file with two outputs ports and one input port.

• PC attached to data / addresses bus.

• Main memory of 128 Mbytes of capacity

• Memory reading and writing use two clock periods

• Data / addresses bus is 32 bits length.

Execute next instruction:

SHL F, 5

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram

c. Design micro instruction format. Control Memory 64k.

d. Design the micro program for the above execution phase.

Lesson 3: Page: 3 / 12

The Control Unit

Tcp

Tmem

MemoriaPrincipal

MemRdWr

a Dir A

ALUentera

Mux X Mux YX0, X1 Y0

LacAcum

LiR.Ins

ResetC.Fases

LFlags Registro Estado

Unidad de Control

Desp./ DI.

OsciladorReloj

señales de control

DIT

LcpCP

Sal A Sal B

Entrada

Lr

Banco deRegistros

Dir A Dir B

Tac

Talu

a Dir B

Bus de datos / direcciones

Selop

2. Lest following elemental computer:

• A 8 operations ALU: +, ×, arithmetic shift left and right AND, OR,

XOR y logical shift right.

• Accumulator register to store temporal values.

• A 16 registers file with two outputs ports and one input port.

• Autoincremented PC.

• Main memory of 16Mbytes of capacity.

• Data bus and addresses bus are 32 bits length.

• All instruction formats are 4 words length.

Lesson 3: Page: 4 / 12

The Control Unit

Tcp

Tmem

MemoriaPrincipal

MemRdWr

a Dir A

ALUentera

Mux X Mux YX0 Y0

LacAcum

LiR.Ins

ResetC.Fases

LFlags Registro Estado

Unidad de Control

Desp./ DI.

OsciladorReloj

señales de control

DIT

LcpCP

Sal A Sal B

Entrada

Lr

Banco deRegistros

Dir A Dir B

Tac

Talu

a Dir B

Bus de datos

Bus de direcciones

TadbdTbdad

Selop

Inc

Execute next instruction:

XOR F, [E + 1234h]

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram

c. Design micro instruction format. Control Memory 64k.

d. Design the micro program for the above execution phase.

3. Lets be the following elemental computer:

• A 16 operations ALU. Input to Output transfer is one of its operations, as

well ass A-B and B-A.

Lesson 3: Page: 5 / 12

The Control Unit

• Accumulator register to store temporal values.

• A 8 registers files with one input port and one output port.

• Autoincremented PC

• Main Memory of 128Mbytes of capacity.

• Data and Addresses buses are 16 bits length.

• Data bus content can be transferred to Addresses bus and vice versa.

Tcp

Tmem

MemoriaPrincipal

MemRd

Wr

a Dir

LacAcum

CP

Tac

Talu

Bus de datos

Bus de direcciones

TadbdTbdad

ALUentera

EntradaLr

Banco deRegistros

Dir.Salida

LiR.Ins ResetC.Fases

LFlags Registro Estado

Unidad de Control

Desp./ DI.

OsciladorReloj

señales de control

DIT

Selop

Inc

Lcp

Execute next instruction:

SUB [B++], A

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram

c. Design microinstruction format. Control Memory 32k.

d. Design the micro program for the above execution phase.

Lesson 3: Page: 6 / 12

The Control Unit

4. Lets be the following elemental computer:

• Two ALUs: one of them is specialized in multiply and divide

operations and the another one in addition and subtraction

operations.

• Both ALUs have an accumulator register to store temporal

values.

• A 32 registers file with one input port and one output port..

• Autoincremented PC

• Main Memory of 32Mbytes of capacity.

• Data and Addresses buses are 32 bits length.

• Data bus content can be transferred to Addresses bus and vice

versa.

• The whole instructions formats are 32 bits length.

Tcp

Tmem

MemoriaPrincipal

MemRd

Wr

a Dir

CP

Bus de datos

Bus de direcciones

TadbdTbdad

EntradaLr

Banco deRegistros

Dir.Salida

LiR.Ins ResetC.Fases

LFlags Registro Estado

Unidad de Control

Desp./ DI.

OsciladorReloj

señales de control

DIT

LacAcum

Tac

Talu

ALUmul / div

Talu2

ALUadd / sub

Lac2Acum2

SelopSelop2

Lcp

Inc

Lesson 3: Page: 7 / 12

The Control Unit

Execute the following instruction:

Div C, D

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram

c. Design microinstruction format. Control Memory 32k.

d. Design the micro program for the above execution phase.

5. Lets be the next elemental computer:

• A 32 operations ALU with the possibility of input to output

transfer.

• Temporal and Accumulator registers to store temporal values

which cannot be used by assembly language.

• 16 register files with two output ports and one input port.

• Stack pointer attached to addresses register

• Main memory: 16 Mbytes of capacity

• Data bus content can be transferred to Addresses bus and vice

versa.

• Buses are 32 bits length

• The whole instruction formats are 32 bits length.

Execute next instruction:

ADD A, B

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram

Lesson 3: Page: 8 / 12

The Control Unit

LtmpTmp

Tcp

Tmem

MemoriaPrincipal

MemRdWr

ALUentera

Mux X Mux YX0, X1 Y0

LacAcum

señales de control

LcpCP

Sal A Sal B

Entrada

Lr

Banco deRegistros

Dir A Dir B

Tac

Talu

Bus de datos / direcciones

Selop

a Dir A

LiR.Ins

ResetC.Fases

LFlags Registro Estado

Unidad de Control

Desp./ DI.

OsciladorReloj

DIT

a Dir B

LspSP

Tsp Ttmp

6. Lets be following elemental computer:

• Two specialized ALUs: one in multiply and dicide operations,

addition and subtraction the another one.

• Temporal and Accumulator register to store temporal values with

no assembly access.

• 32 registers file with one input and output ports.

• Autoincremented PC..

• Stack pointer attached to addresses bus.

• Main memory of 32Mbytes of capacity

• Buses are 32 bits length.

• The whole instruction formats are 32 bits length.

Lesson 3: Page: 9 / 12

The Control Unit

• Data bus content can be transferred to Addresses bus and vice

versa.

Tcp

Tmem

MemoriaPrincipal

MemRd

Wr

a Dir

LcpCP

Bus de datos

Bus de direcciones

TadbdTbdad

EntradaLr

Banco deRegistros

Dir.Salida

LiR.Ins ResetC.Fases

LFlags Registro Estado

Unidad de Control

Desp./ DI.

OsciladorReloj

señales de control

DIT

LacAcum

Tac

Talu

ALU 1mul / div

Talu2

ALU 2add / sub

Lac2Acum2

SelopSelop2

LtmpTmp

LspSP

Tsp Ttmp

Mux XX0

Inc

Execute following isntructions:

ADD [[B + 1000h]], [C + 1234h]

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram

7. Lets be a elemental computer as follows.:

• Two specialized ALUs. a fixed point ALU and a floating point one.

Lesson 3: Page: 10 / 12

The Control Unit

• Temporal and Accumulator registers to store temporal values

which cannot be used by assembly language.

• Two 32 registers file with one input and output ports. One for

fixed point registers and the another for floating point ones.

• Autoincremented PC

• Main Memory of 4Gbytes of capacity.

• Buses are 32 bits length.

• The whole instruction formats are 32 bits length.

• Data bus content can be transferred to Addresses bus and vice

versa.

Tcp

Tmem

MemoriaPrincipal

MemRdWr

a Dir A

LcpCP

Bus de datos

Bus de direcciones

TadbdTbdad

EntradaLr

Banco deRegistrosde coma

fija

Dir ASalida

LacAcum

Tac

Talu

LiR.Ins ResetC.Fases

LFlags Registro Estado

Unidad de Control

Desp./ DI.

OsciladorReloj

señales de control

DIT

a Dir B

Lac2

Talu2

Acum2

Sal A Sal B

EntradaLr2

Banco deRegistrosde comaflotante

Dir A Dir B

Inc

ALUcoma fija

Mux X Mux YX0 Y0

Selop

Ttmp

LtmpTmp

ALUcoma flotante

Mux X Mux YX0' Y0'

Selop2

Execute following instruction:

MULF D, C, 3.27

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram

Lesson 3: Page: 11 / 12

The Control Unit

8. Lets be next elemental computer:

• A 16 operations ALU.

• 3 registers file: B, C and D.

• Main Memory of 640Kbytes.

• Data and Addresses buses are 32 bits length

Execute following instruction:

SUB B, [ C + 1000h ]

a. Modify bellow computer if needed

b. Describe elemental operation to perform in each execution phase

c. Draw above instruction chronogram

Lesson 3: Page: 12 / 12

The Control Unit

9. Lets be following elemental computer:

• A 16 operations ALU.

• Datapath contains PC, SP and Accumulator register, as well as a

3 registers file.

• Main memory 32 Kbytes of capacity.

• Data bus: 8 bits.

• Addreses bus: 16 bits.

• Instructions have different sizes

Execute next instruction:

POP B

a. Describe elemental operation to perform in each execution phase

b. Draw above instruction chronogram