Top Banner

of 13

Myth8 Processor Datapath

Apr 14, 2018

Download

Documents

Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
  • 7/27/2019 Myth8 Processor Datapath

    1/13

    E

    E

    C

    S

    3

    6

    6

    :

    C

    o

    m

    p

    u

    t

    e

    r

    A

    r

    c

    h

    i

    t

    e

    c

    t

    u

    r

    e

    L

    e

    c

    t

    u

    r

    e

    N

    o

    t

    e

    s

    #

    8

    P

    r

    o

    c

    e

    s

    s

    o

    r

    D

    e

    s

    i

    g

    n

    :

    M

    y

    t

    h

    8

    D

    a

    t

    a

    p

    a

    t

    h

    a

    n

    d

    C

    o

    n

    t

    r

    o

    l

    S

    h

    a

    n

    t

    a

    n

    u

    D

    u

    t

    t

    D

    e

    p

    a

    r

    t

    m

    e

    n

    t

    o

    f

    E

    l

    e

    c

    t

    r

    i

    c

    a

    l

    $

    C

    o

    m

    p

    u

    t

    e

    r

    E

    n

    g

    i

    n

    e

    e

    r

    i

    n

    g

    U

    n

    i

    v

    e

    r

    s

    i

    t

    y

    o

    f

    I

    l

    l

    i

    n

    o

    i

    s

    ,

    C

    h

    i

    c

    a

    g

    o

    P

    h

    o

    n

    e

    :

    (

    3

    1

    2

    )

    3

    5

    5

    -

    1

    3

    1

    4

    e

    -

    m

    a

    i

    l

    :

    d

    u

    t

    t

    @

    e

    c

    e

    .

    u

    i

    c

    .

    e

    d

    u

    U

    R

    L

    :

    h

    t

    t

    p

    :

    /

    /

    w

    w

    w

    .

    e

    c

    e

    .

    u

    i

    c

    .

    e

    d

    u

    /

    ~

    d

    u

    t

    t

    S

    h

    a

    n

    t

    a

    n

    u

    D

    u

    t

    t

  • 7/27/2019 Myth8 Processor Datapath

    2/13

    Register File

    ALU

    controlsignals

    controlsignals

    Control

    Unit(CU)

    rkrj

    rirj rk

    Fetch

    & Load IR(> 1cc)

    (b) A Simple Instr-

    uction Flow

    MEMORY SYSTEM

    Memory Data Bus

    CPU

    readwrite

    Mux

    Read Bus B

    Read Bus A

    alu_sel[0..2]

    a_sel[0..2]

    b_sel[0..2]

    MAR

    mar_sel

    8

    8

    8

    MDR

    ir1_selir0_sel

    r0write

    ri_sel

    rj_sel

    rk_sel

    cout, m7, v

    8 8

    Write Bus

    r7write

    Memory Address Bus

    opcode

    cin

    IR1IR0

    Clk

    Clk

    Clk

    result_sel[0..1]

    Clk

    4-8 sign ext.

    opcode ri

    dr_enb dr_sel[0..1]

    Clk

    (a) The Myth8 Processor

    (1cc)

    Decode &

    PCIncr

    (>= 1cc)

    (in ALU)

    & Write

    Read, Exe.

  • 7/27/2019 Myth8 Processor Datapath

    3/13

    M

    a

    i

    n

    d

    i

    e

    r

    e

    n

    c

    e

    s

    b

    e

    t

    w

    e

    e

    n

    M

    y

    t

    h

    8

    a

    n

    d

    E

    d

    u

    3

    2

    1

    .

    M

    y

    t

    h

    8

    h

    a

    s

    8

    -

    b

    i

    t

    w

    i

    d

    e

    d

    a

    t

    a

    p

    a

    t

    h

    s

    ,

    i

    n

    c

    l

    u

    d

    i

    n

    g

    m

    e

    m

    o

    r

    y

    b

    u

    s

    w

    i

    d

    b

    i

    t

    s

    f

    o

    r

    t

    h

    e

    E

    d

    u

    3

    2

    2

    .

    W

    o

    r

    d

    s

    i

    z

    e

    s

    a

    r

    e

    s

    i

    m

    i

    l

    a

    r

    l

    y

    d

    i

    e

    r

    e

    n

    t

    3

    .

    T

    h

    e

    r

    e

    i

    s

    n

    o

    e

    x

    p

    l

    i

    c

    i

    t

    P

    C

    i

    n

    t

    h

    e

    M

    y

    t

    h

    8

    .

    T

    h

    e

    P

    C

    r

    e

    s

    i

    d

    e

    s

    i

    n

    r

    e

    g

    i

    s

    t

    e

    r

    l

    e

    |

    t

    h

    i

    s

    m

    a

    k

    e

    s

    l

    o

    a

    d

    i

    n

    g

    t

    h

    e

    i

    n

    s

    t

    r

    u

    c

    t

    i

    o

    n

    a

    d

    d

    r

    e

    s

    s

    t

    o

    t

    h

    a

    d

    d

    r

    e

    s

    s

    b

    u

    s

    m

    o

    r

    e

    c

    o

    m

    p

    l

    e

    x

    4

    .

    I

    n

    s

    t

    r

    u

    c

    t

    i

    o

    n

    s

    i

    z

    e

    i

    s

    1

    6

    b

    i

    t

    s

    f

    o

    r

    t

    h

    e

    M

    y

    t

    h

    8

    i

    t

    s

    i

    s

    3

    2

    b

    i

    t

    s

    f

    o

    r

    t

    h

    e

    E

    t

    w

    o

    m

    e

    m

    o

    r

    y

    f

    e

    t

    c

    h

    e

    s

    a

    r

    e

    r

    e

    q

    u

    i

    r

    e

    d

    t

    o

    g

    e

    t

    a

    s

    i

    n

    g

    l

    e

    i

    n

    s

    t

    r

    u

    c

    t

    i

    o

    n

    i

    n

    t

    v

    s

    .

    o

    n

    l

    y

    o

    n

    e

    f

    o

    r

    t

    h

    e

    E

    d

    u

    3

    2

    (

    t

    h

    e

    i

    n

    s

    t

    r

    u

    c

    t

    i

    o

    n

    s

    i

    z

    e

    a

    n

    d

    t

    h

    e

    d

    a

    t

    a

    a

    r

    e

    e

    q

    u

    a

    l

    i

    n

    t

    h

    e

    E

    d

    u

    3

    2

    )

    .

    5

    .

    T

    h

    e

    M

    y

    t

    h

    8

    d

    o

    e

    s

    n

    o

    t

    h

    a

    v

    e

    a

    n

    y

    A

    L

    U

    i

    n

    p

    u

    t

    a

    n

    d

    o

    u

    t

    p

    u

    t

    r

    e

    g

    i

    c

    o

    u

    l

    d

    p

    o

    t

    e

    n

    t

    i

    a

    l

    l

    y

    c

    a

    u

    s

    e

    a

    (

    m

    u

    l

    t

    i

    p

    l

    e

    c

    c

    )

    r

    a

    c

    e

    c

    o

    n

    d

    i

    t

    i

    o

    n

    f

    o

    r

    m

    u

    l

    t

    i

    o

    p

    e

    r

    a

    t

    i

    o

    n

    s

    a

    s

    t

    h

    e

    A

    L

    U

    o

    /

    p

    c

    a

    n

    w

    r

    i

    t

    e

    t

    o

    t

    h

    e

    d

    e

    s

    t

    i

    n

    a

    t

    i

    o

    n

    r

    e

    g

    i

    s

    t

    e

    r

    o

    p

    e

    r

    a

    t

    i

    o

    n

    i

    s

    c

    o

    m

    p

    l

    e

    t

    e

    (

    i

    f

    t

    h

    e

    C

    U

    i

    s

    n

    o

    t

    p

    r

    o

    p

    e

    r

    l

    y

    d

    e

    s

    i

    g

    n

    e

    d

    )

    .

    r

    e

    g

    .

    i

    s

    t

    h

    e

    s

    a

    m

    e

    a

    s

    a

    n

    y

    s

    o

    u

    r

    c

    e

    r

    e

    g

    .

    t

    h

    e

    i

    /

    p

    t

    o

    t

    h

    e

    A

    L

    U

    c

    h

    a

    n

    g

    e

    s

    o

    p

    e

    r

    a

    t

    i

    o

    n

    i

    s

    c

    o

    m

    p

    l

    e

    t

    e

    d

    p

    o

    t

    e

    n

    t

    i

    a

    l

    l

    y

    c

    a

    u

    s

    i

    n

    g

    a

    n

    i

    n

    c

    o

    r

    r

    e

    c

    t

    r

    e

    s

    u

    l

    t

    .

  • 7/27/2019 Myth8 Processor Datapath

    4/13

    result_sel=00

    (select write bus)

    result_sel=00

    (select write bus)

    cntr0=1(MUL DONE) [rj -> ReadBusA

    rk -> ReadBusB]

    [rj -> ReadBusA

    rk -> ReadBusBcounter ,- m-1]

    [r7

  • 7/27/2019 Myth8 Processor Datapath

    5/13

    P

    r

    o

    g

    r

    a

    m

    m

    i

    n

    g

    l

    a

    n

    g

    u

    a

    g

    e

    -

    t

    y

    p

    e

    r

    e

    p

    r

    e

    s

    e

    n

    t

    a

    t

    i

    o

    n

    o

    f

    a

    b

    o

    v

    e

    M

    o

    o

    r

    e

    F

    S

    M

    .

    N

    o

    t

    e

    t

    h

    a

    t

    m

    y

    t

    h

    s

    i

    m

    m

    i

    c

    r

    s

    y

    n

    t

    a

    x

    i

    s

    s

    l

    i

    g

    h

    t

    l

    y

    d

    i

    e

    r

    e

    n

    t

    .

    1

    .

    /

    /

    r

    7

    =

    i

    n

    i

    t

    i

    a

    l

    v

    a

    l

    u

    e

    (

    s

    e

    t

    b

    y

    a

    r

    e

    s

    e

    t

    s

    i

    g

    n

    a

    l

    )

    2

    .

    /

    /

    L

    o

    a

    d

    r

    7

    i

    n

    t

    o

    M

    A

    R

    a

    n

    d

    r

    6

    F

    e

    t

    c

    h

    0

    :

    a

    s

    e

    l

    =

    7

    b

    s

    e

    l

    =

    7

    m

    a

    r

    s

    e

    l

    =

    1

    r

    6

    w

    r

    i

    t

    e

    =

    1

    3

    .

    /

    /

    F

    e

    t

    c

    h

    h

    i

    g

    h

    e

    r

    -

    o

    r

    d

    e

    r

    b

    y

    t

    e

    o

    f

    1

    6

    -

    b

    i

    t

    i

    n

    s

    t

    r

    u

    c

    t

    i

    o

    n

    n

    o

    t

    e

    t

    h

    a

    t

    t

    h

    e

    m

    e

    m

    o

    r

    y

    i

    s

    b

    y

    t

    e

    a

    d

    d

    r

    e

    s

    s

    a

    b

    l

    e

    F

    e

    t

    c

    h

    1

    :

    i

    r

    0

    s

    e

    l

    =

    1

    r

    e

    a

    d

    =

    1

    ,

    a

    s

    e

    l

    =

    6

    a

    l

    u

    s

    e

    l

    =

    A

    D

    D

    A

    r

    7

    w

    r

    i

    t

    e

    =

    1

    /

    /

    c

    o

    n

    t

    r

    o

    l

    s

    i

    g

    n

    a

    l

    s

    n

    o

    r

    7

    r

    6

    +

    1

    ]

    i

    f

    w

    a

    i

    t

    t

    h

    e

    n

    g

    o

    t

    o

    F

    e

    t

    c

    h

    1

    e

    n

    d

    i

    f

    4

    .

    /

    /

    L

    o

    a

    d

    r

    7

    i

    n

    t

    o

    M

    A

    R

    a

    n

    d

    r

    6

    F

    e

    t

    c

    h

    2

    :

    a

    s

    e

    l

    =

    7

    b

    s

    e

    l

    =

    7

    m

    a

    r

    s

    e

    l

    =

    1

    r

    6

    w

    r

    i

    t

    e

    =

    1

    5

    .

    /

    /

    F

    e

    t

    c

    h

    l

    o

    w

    e

    r

    -

    o

    r

    d

    e

    r

    b

    y

    t

    e

    o

    f

    1

    6

    -

    b

    i

    t

    i

    n

    s

    t

    r

    u

    c

    t

    i

    o

    n

    F

    e

    t

    c

    h

    3

    :

    i

    r

    1

    s

    e

    l

    =

    1

    r

    e

    a

    d

    =

    1

    ,

    a

    s

    e

    l

    =

    6

    a

    l

    u

    s

    e

    l

    =

    A

    D

    D

    A

    r

    7

    w

    r

    i

    t

    e

    =

    1

    /

    /

    c

    o

    n

    t

    r

    o

    l

    s

    i

    g

    n

    a

    l

    s

    n

    o

    t

    s

    p

    e

    c

    i

    f

    w

    a

    i

    t

    t

    h

    e

    n

    g

    o

    t

    o

    F

    e

    t

    c

    h

    3

    e

    n

    d

    i

    f

    6

    .

    D

    e

    c

    o

    d

    e

    :

    i

    f

    (

    o

    p

    c

    o

    d

    e

    =

    =

    A

    D

    D

    )

    t

    h

    e

    n

    g

    o

    t

    o

    A

    d

    d

    e

    l

    s

    e

    i

    f

    (

    o

    p

    c

    o

    d

    e

    =

    =

    M

    U

    L

    )

    t

    h

    e

    n

    g

    o

    t

    o

    M

    u

    l

    e

    n

    d

    i

    f

    /

    /

    A

    D

    D

    a

    n

    d

    M

    U

    L

    a

    r

    e

    p

    r

    e

    d

    e

    n

    e

    d

    c

    o

    n

    s

    t

    a

    n

    t

    s

    c

    o

    r

    r

    e

    s

    p

    o

    n

    d

    i

    n

    g

    t

    o

    t

    h

    e

    o

    p

    c

    o

    d

    e

    v

    a

    l

    u

    e

    s

    f

    o

    r

    t

    h

    e

    s

    e

    i

    n

    s

    7

    .

    A

    d

    d

    :

    r

    j

    s

    e

    l

    =

    1

    r

    k

    s

    e

    l

    =

    1

    a

    l

    u

    s

    e

    l

    =

    A

    D

    D

    c

    i

    n

    =

    0

    r

    e

    s

    u

    l

    t

    s

    e

    l

    =

    A

    L

    U

    r

    i

    s

    e

    l

    =

    1

    ,

    /

    /

    1

    c

    c

    A

    d

    d

    o

    p

    e

    r

    a

    t

    i

    o

    n

    ,

    s

    e

    l

    e

    c

    t

    r

    e

    g

    i

    s

    t

    e

    r

    s

    p

    e

    c

    i

    e

    d

    i

    n

    r

    i

    e

    l

    d

    o

    f

    I

    R

    f

    o

    r

    w

    r

    i

    t

    i

    n

    g

    g

    o

    t

    o

    F

    e

    t

    c

    h

    0

    8

    .

    M

    u

    l

    :

    r

    j

    s

    e

    l

    =

    1

    r

    k

    s

    e

    l

    =

    1

    c

    s

    e

    l

    =

    1

    c

    o

    u

    n

    t

    =

    m

    ;

    2

    ,

    /

    /

    M

    u

    l

    t

    i

    p

    l

    i

    c

    a

    t

    i

    o

    n

    t

    a

    k

    e

    s

    m

    c

    c

    '

    s

    .

    A

    f

    t

    e

    r

    t

    h

    i

    s

    c

    c

    ,

    1

    c

    c

    w

    i

    l

    l

    h

    a

    v

    e

    e

    l

    a

    p

    s

    e

    d

    s

    i

    n

    c

    e

    r

    e

    g

    i

    s

    t

    e

    r

    r

    e

    a

    d

    s

    a

    n

    d

    m

    ;

    2

    w

    t

    h

    e

    c

    o

    u

    n

    t

    e

    r

    .

    N

    o

    t

    e

    t

    h

    a

    t

    t

    h

    e

    m

    y

    t

    h

    8

    d

    o

    e

    s

    n

    o

    t

    h

    a

    v

    e

    e

    i

    t

    h

    e

    r

    a

    m

    u

    l

    t

    i

    p

    l

    i

    e

    r

    i

    n

    i

    t

    s

    A

    L

    U

    n

    o

    r

    a

    c

    o

    u

    n

    t

    e

    r

    .

    T

    h

    e

    s

    e

    h

    e

    r

    e

    t

    o

    i

    l

    l

    u

    s

    t

    r

    a

    t

    e

    t

    h

    e

    C

    U

    d

    e

    s

    i

    g

    n

    f

    o

    r

    m

    u

    l

    t

    i

    p

    l

    e

    c

    c

    A

    L

    U

    e

    x

    e

    c

    u

    t

    i

    o

    n

    p

    h

    a

    s

    e

    .

    9

    .

    M

    u

    l

    W

    a

    i

    t

    :

    r

    j

    s

    e

    l

    =

    1

    ,

    r

    k

    s

    e

    l

    =

    1

    ,

    i

    f

    (

    c

    n

    t

    r

    0

    =

    =

    0

    )

    t

    h

    e

    n

    g

    o

    t

    o

    M

    u

    l

    W

    a

    i

    t

    e

    n

    d

    i

    f

    1

    0

    .

    a

    l

    u

    s

    e

    l

    =

    M

    U

    L

    r

    e

    s

    u

    l

    t

    s

    e

    l

    =

    A

    L

    U

    r

    i

    s

    e

    l

    =

    1

    ,

    g

    o

    t

    o

    F

    e

    t

    c

    h

    0

    e

    n

    d

    i

    f

  • 7/27/2019 Myth8 Processor Datapath

    6/13

    Register File

    ALU

    controlsignals

    controlsignals

    Con

    trolUnit(CU)

    rkrj

    rirj rk

    MEMORY SYSTEM

    Memory Data Bus

    CPU

    readwrite

    Mux

    Read Bus BRead Bus A

    alu_sel[0..2]

    a_sel[0..2]

    b_sel[0..2]

    MAR

    mar_sel

    8

    8

    8

    MDR

    ir1_selir0_sel

    r0write

    ri_sel

    rj_sel

    rk_sel

    cout, m7, v

    8 8

    Write Bus

    r7write

    Memory Address Bus

    opcode

    cin

    IR1IR0

    Clk

    Clk

    Clk

    result_sel[0..1]

    Clk

    4-8 sign ext.

    opcode ri

    dr_enb dr_sel[0..1]

    Clk

    The Myth8 Processor

  • 7/27/2019 Myth8 Processor Datapath

    7/13

    Register File

    ALU

    controlsignals

    controlsignals

    Con

    trolUnit(CU)

    rkrj

    rirj rk

    MEMORY SYSTEM

    Memory Data Bus

    CPU

    readwrite

    Mux

    Read Bus BRead Bus A

    alu_sel[0..2]

    a_sel[0..2]

    b_sel[0..2]

    MAR

    mar_sel

    8

    8

    8

    MDR

    ir1_selir0_sel

    r0write

    ri_sel

    rj_sel

    rk_sel

    cout, m7, v

    8 8

    Write Bus

    r7write

    Memory Address Bus

    opcode

    cin

    IR1IR0

    Clk

    Clk

    Clk

    result_sel[0..1]

    Clk

    4-8 sign ext.

    opcode ri

    dr_enb dr_sel[0..1]

    Clk

    The Myth8 Processor

  • 7/27/2019 Myth8 Processor Datapath

    8/13

    C U F S M D e s i g n S t r a t e g i e s : D e s i g n C o r r e c t n e s s

    1 . F o r a m a j o r o p e r a t i o n ( e . g . , f e t c h & d e c o d e ) , t r a c e t h e d a t a p a t h t h r o u g h

    t h e c o m p u t e r s y s t e m ( p r o c e s s o r , m e m o r y , I / O , e t c . ) n e e d e d f o r e x e c u t i n g

    t h i s o p e r a t i o n .

    2 . B r e a k u p t h e d a t a p a t h i n t o s u b p a t h s s . t . e a c h s u b p a t h s t a r t s f r o m a

    r e g i s t e r r e a d ( e x p l i c i t o r i m p l i c i t ) , h a s a n o p t i o n a l o p e r a t i o n , a n d , e x c e p t

    p o s s i b l y t h e l a s t s u b p a t h , e n d s w i t h a r e g i s t e r w r i t e .

    3 . E a c h s u b p a t h n e e d s t o b e i m p l e m e n t e d b y a s i n g l e s t a t e ( c o n t r o l s i g n a l s

    t o i m p l e m e n t t h e s u b p a t h a r e s e t i n t h e c o r r e s p o n d i n g s t a t e ) .

    4 . A s u b p a t h i s d e p e n d e n t o n t h e d a t a p r o d u c e d a s a r e g i s t e r w r i t e i n t h e

    p r e v i o u s s u b p a t h . T h i s d a t a d e p e n d e n c y i s r e e c t e d b y t h e i r c o r r e s p o n d -

    i n g s t a t e s f o l l o w i n g e a c h o t h e r i n t h e s a m e o r d e r a s t h e s u b p a t h s .

    Subpath nSubpath 1 Subpath 2

    Register

    Register

    Register

    Register

    [operation] [operation] [operation] [operation]

    Major Operation

  • 7/27/2019 Myth8 Processor Datapath

    9/13

    C U F S M D e s i g n S t r a t e g i e s : D e s i g n C o r r e c t n e s s ( c o n t d . )

    1 . T h e s u b p a t h d e t e r m i n a t i o n f o r t h e f e t c h - i n t o - I R 1 - & - d e c o d e a n d i n c r e -

    m e n t p c=

    r 7 o p e r a t i o n s i s i l l u s t r a t e d i n t h e g u r e b e l o w s u b p a t h s a r e

    # ' e d i n i t a l i c s

    Register File

    ALU

    O1

    O2

    O1

    O2

    O1

    O2

    O1

    O2

    MEMORY SYSTEM

    Memory Data Bus

    CPU

    readwrite

    dr_enb

    Mux

    Read Bus BRead Bus A

    alu_sel[0..2]

    a_sel[0..2]

    b_sel[0..2]

    dr_sel[0..1]

    result_sel[0..1]

    MAR

    mar_sel

    8

    8

    8

    Memory Address Bus

    MDRIR1IR0

    ir1_selir0_sel

    r0write

    r0writeri_sel

    rj_sel

    rk_sel

    cin

    cout, m7, v

    opcode

    8 8

    r7

    r6

    ANDADDA

    Write Bus

    Myth8 and "datapaths" for fetch-decode & increment pcDatapath for fetch (to IR1) and decode

    "Datapath" for increment pc=r7

    1

    2

    3

    1

    2

  • 7/27/2019 Myth8 Processor Datapath

    10/13

    C

    U

    F

    S

    M

    D

    e

    s

    i

    g

    n

    S

    t

    r

    a

    t

    e

    g

    i

    e

    s

    :

    D

    e

    s

    i

    g

    n

    C

    o

    r

    r

    e

    c

    t

    n

    e

    s

    s

    {

    O

    t

    h

    e

    1

    .

    C

    o

    n

    n

    e

    c

    t

    i

    o

    n

    s

    t

    o

    t

    h

    e

    i

    n

    p

    u

    t

    o

    f

    t

    h

    e

    A

    L

    U

    (

    o

    r

    a

    n

    y

    c

    o

    m

    b

    i

    n

    a

    t

    i

    o

    n

    a

    l

    t

    o

    b

    e

    m

    a

    i

    n

    t

    a

    i

    n

    e

    d

    f

    o

    r

    t

    h

    e

    e

    n

    t

    i

    r

    e

    p

    e

    r

    i

    o

    d

    o

    f

    t

    h

    e

    r

    e

    q

    u

    i

    r

    e

    d

    o

    p

    e

    r

    a

    t

    i

    o

    i

    f

    t

    h

    e

    r

    e

    i

    s

    a

    m

    u

    l

    t

    i

    p

    l

    i

    e

    r

    i

    n

    t

    h

    e

    A

    L

    U

    ,

    a

    n

    d

    m

    u

    l

    t

    i

    p

    l

    i

    c

    a

    t

    i

    o

    n

    t

    a

    k

    e

    s

    1

    0

    t

    h

    e

    r

    e

    a

    d

    c

    o

    n

    t

    r

    o

    l

    s

    i

    g

    n

    a

    l

    s

    (

    a

    s

    e

    l

    b

    s

    e

    l

    ]

    o

    r

    r

    j

    s

    e

    l

    r

    k

    s

    e

    l

    ]

    )

    i

    n

    t

    h

    a

    v

    e

    t

    o

    b

    e

    m

    a

    i

    n

    t

    a

    i

    n

    e

    d

    f

    o

    r

    t

    h

    e

    e

    n

    t

    i

    r

    e

    1

    0

    c

    c

    '

    s

    s

    o

    t

    h

    a

    t

    t

    h

    e

    o

    p

    e

    r

    a

    n

    r

    e

    m

    a

    i

    n

    c

    o

    n

    n

    e

    c

    t

    e

    d

    t

    o

    t

    h

    e

    m

    u

    l

    t

    i

    p

    l

    i

    e

    r

    '

    s

    i

    n

    p

    u

    t

    s

    f

    o

    r

    t

    h

    e

    e

    n

    t

    i

    r

    e

    1

    0

    c

    2

    .

    I

    n

    m

    u

    l

    t

    i

    p

    l

    e

    -

    c

    c

    o

    p

    e

    r

    a

    t

    i

    o

    n

    s

    ,

    t

    h

    e

    w

    r

    i

    t

    e

    c

    o

    n

    t

    r

    o

    l

    s

    i

    g

    n

    a

    l

    f

    o

    r

    w

    r

    i

    t

    i

    n

    g

    t

    i

    n

    a

    t

    i

    o

    n

    r

    e

    g

    i

    s

    t

    e

    r

    s

    h

    o

    u

    l

    d

    o

    n

    l

    y

    b

    e

    v

    a

    l

    i

    d

    i

    n

    t

    h

    e

    l

    a

    s

    t

    c

    c

    o

    f

    t

    h

    e

    o

    a

    v

    o

    i

    d

    m

    u

    t

    i

    p

    l

    e

    -

    c

    c

    r

    a

    c

    e

    c

    o

    n

    d

    i

    t

    i

    o

    n

    s

    .

    S

    o

    i

    f

    M

    U

    L

    r

    1

    r

    2

    r

    3

    ]

    i

    s

    t

    h

    e

    t

    i

    o

    n

    i

    n

    s

    t

    r

    u

    c

    t

    i

    o

    n

    (

    r

    1

    r

    2

    r

    3

    )

    a

    n

    d

    t

    a

    k

    e

    s

    1

    0

    c

    c

    ,

    a

    s

    e

    l

    =

    2

    b

    r

    j

    s

    e

    l

    =

    1

    r

    k

    s

    e

    l

    =

    1

    )

    s

    h

    o

    u

    l

    d

    b

    e

    m

    a

    i

    n

    t

    a

    i

    n

    e

    d

    f

    o

    r

    t

    h

    e

    e

    n

    t

    i

    r

    e

    1

    0

    r

    1

    w

    r

    i

    t

    e

    =

    1

    (

    o

    r

    r

    i

    s

    e

    l

    =

    1

    )

    s

    h

    o

    u

    l

    d

    o

    n

    l

    y

    b

    e

    a

    c

    t

    i

    v

    e

    i

    n

    t

    h

    e

    1

    0

    '

    t

    3

    .

    B

    e

    c

    a

    r

    e

    f

    u

    l

    n

    o

    t

    t

    o

    k

    e

    e

    p

    o

    n

    l

    o

    a

    d

    i

    n

    g

    d

    a

    t

    a

    i

    n

    t

    o

    a

    r

    e

    g

    i

    s

    t

    e

    r

    o

    v

    e

    r

    m

    w

    h

    i

    l

    e

    i

    t

    s

    c

    o

    n

    t

    e

    n

    t

    i

    s

    s

    u

    p

    p

    o

    s

    e

    d

    t

    o

    b

    e

    c

    h

    a

    n

    g

    i

    n

    g

    o

    v

    e

    r

    t

    h

    o

    s

    e

    c

    c

    '

    s

    (

    e

    t

    h

    e

    i

    n

    i

    t

    i

    a

    l

    c

    o

    u

    n

    t

    v

    a

    l

    u

    e

    i

    n

    t

    h

    e

    c

    o

    u

    n

    t

    e

    r

    i

    n

    t

    h

    e

    h

    y

    p

    o

    t

    e

    h

    t

    i

    c

    a

    l

    M

    y

    t

    h

  • 7/27/2019 Myth8 Processor Datapath

    11/13

    C U F S M D e s i g n S t r a t e g i e s : D e s i g n E c i e n c y

    1 . W h i l e s u b p a t h s o f o n e o p e r a t i o n n e e d t o b e i m p l e m e n t e d i n s e p a r a t e

    s t a t e s , s u b p a t h s o f 2 o r m o r e o p e r a t i o n s ( a t m o s t o n e s u b p a t h f r o m e a c h

    o p e r a t i o n ) m a y b e c o m b i n e d i n t o o n e s t a t e i f : ( a ) t h e r e i s n o d a t a d e p e n -

    d e n c y b e t w e e n t h e m ( d a t a p r o d u c e d b y o n e i s n o t n e e d e d b y t h e o t h e r ) ,

    a n d ( b ) t h e r e a r e n o r e s o u r c e c o n i c t s | t h e s a m e r e s o u r c e i s n o t n e e d e d

    f o r m o r e t h a n o n e p u r p o s e i n a n y c l o c k c y c l e . R e s o u r c e s i n c l u d e r e g i s t e r s ,

    A L U , b u s e s a n d o t h e r c o n n e c t i o n s , m e m o r y .

    2 . I m p l e m e n t i n g s u b p a t h s o f d i e r e n t o p e r a t i o n s s i m u l t a n e o u s l y i n o n e s t a t e ,

    s p e e d s u p t h e o v e r a l l s p e e d o v e r a l l o p e r a t i o n s a n d r e d u c e s t h e n u m b e r o f

    s t a t e s r e q u i r e d i n t h e C o n t r o l U n i t .

    Register File

    ALU

    O1

    O2

    O1

    O2

    O1

    O2

    O1

    O2

    MEMORY SYSTEM

    Memory Data Bus

    CPU

    readwrite

    dr_enb

    Mux

    Read Bus BRead Bus A

    alu_sel[0..2]

    a_sel[0..2]

    b_sel[0..2]

    dr_sel[0..1]

    result_sel[0..1]

    MAR

    mar_sel

    8

    8

    8

    Memory Address Bus

    MDRIR1IR0

    ir1_selir0_sel

    r0write

    r0writeri_sel

    rj_sel

    rk_sel

    cin

    cout, m7, v

    opcode

    8 8

    r7

    r6

    ANDADDA

    Write Bus

    Myth8 and "datapaths" for fetch-decode & increment pc

    Datapath for fetch (to IR1) and decode

    "Datapath" for increment pc=r7

    1

    2

    3

    1

    2

  • 7/27/2019 Myth8 Processor Datapath

    12/13

    C U F S M D e s i g n S t r a t e g i e s : D e s i g n E c i e n c y ( c o n t d . )

    1 . I n t h e g u r e b e l o w , s u b p a t h s 1 o f f e t c h - i n t o - I R 1 - & - d e c o d e a n d i n c r e -

    m e n t p c=

    r 7 o p e r a t i o n s c a n b e c o m b i n e d i n t o o n e s t a t e , a s c a n s u b p a t h s

    2 o f t h e s e o p e r a t i o n s | n o t e n o r e s o u r c e c o n i c t .

    Register File

    ALU

    O1

    O2

    O1

    O2

    O1

    O2

    O1

    O2

    MEMORY SYSTEM

    Memory Data Bus

    CPU

    readwrite

    dr_enb

    Mux

    Read Bus BRead Bus A

    alu_sel[0..2]

    a_sel[0..2]

    b_sel[0..2]

    dr_sel[0..1]

    result_sel[0..1]

    MAR

    mar_sel

    8

    8

    8

    Memory Address Bus

    MDRIR1IR0

    ir1_selir0_sel

    r0write

    r0writeri_sel

    rj_sel

    rk_sel

    cin

    cout, m7, v

    opcode

    8 8

    r7

    r6

    ANDADDA

    Write Bus

    Myth8 and "datapaths" for fetch-decode & increment pcDatapath for fetch (to IR1) and decode

    "Datapath" for increment pc=r7

    1

    2

    3

    1

    2

  • 7/27/2019 Myth8 Processor Datapath

    13/13

    P i p e l i n e d M y t h 8 P r o c e s s o r

    Register File

    O1

    O2

    O1

    O2

    O1

    O2

    O1

    O2

    ALUalu_sel[0..2]

    cin

    cout, m7, v Decode & ALU

    Stage

    ALU o/pregister

    8Reg. fileo/p regs

    MEMORY SYSTEM

    Memory Data Bus

    CPU

    readwrite

    dr_enb

    Mux

    a_sel[0..2]b_sel[0..2]

    dr_sel[0..1]

    result_sel[0..1]

    MAR

    mar_sel

    8

    8

    Memory Address Bus

    MDR

    r0write

    r0writeri_selrj_sel

    rk_sel

    8 8

    Write Bus

    Read Bus A Read Bus B

    IR0IR1

    ir1_sel ir0_sel

    FetchCU

    ReadCU

    ALUCU

    WriteCU

    Opcode register

    opcode

    Fetch Stage

    Decode & Read

    Stage

    Decode &

    Write

    Stage

    The Myth8 Pipelined Processor