DUAL-PORT MEMORY BLOCK DIAGRAM.pdf

DUAL-PORT MEMORY BLOCK DIAGRAM DATA

CPU

L

R 

DATA I/O

DATA I/O

DATA

CPU

OR 

OR 

I/O

DEVICE ADDRESS

"L"

L ADDRESS DECODER 

R/W

BUSY, INTERRUPT, SEMAPHORE

DUAL/PORT RAM MEMORY CELLS

CONTROL LOGIC

R 

ADDRESS

ADDRESS DECODER  R/W

I/O DEVICE

"R"

BUSY, INTERRUPT, SEMAPHORE

1

DUALL-PORT RAM CELL L SIDE WRITE DRIVERS

L SELECT (DECODED ADDRESS) L WRITE

   E    N    I    L    T    I    B    A    T    A    D    L

R SIDE WRITE DRIVERS

WR  1

WR  1

WR  0

WR  0

RD

R SELECT (DECODED ADDRESS) R WRITE

RD

   E    N    I    L    T    I    B    A    T    A    D    R

RAM CELL LATCH

L SIDE READ DRIVERS

R SIDE READ DRIVERS

2

DUALL-PORT RAM CELL - Read  L SIDE WRITE DRIVERS

L SELECT (DECODED ADDRESS) L WRITE

   E    N    I    L    T    I    B    A    T    A    D    L

R SIDE WRITE DRIVERS

WR  1

WR  1

WR  0

WR  0

RD

R SELECT (DECODED ADDRESS) R WRITE

RD

   E    N    I    L    T    I    B    A    T    A    D    R

RAM CELL LATCH

L SIDE READ DRIVERS

R SIDE READ DRIVERS

3

DUALL-PORT RAM CELL - Write L SIDE WRITE DRIVERS

L SELECT (DECODED ADDRESS) L WRITE

   E    N    I    L    T    I    B    A    T    A    D    L

R SIDE WRITE DRIVERS

WR  1

WR  1

WR  0

WR  0

RD

R SELECT (DECODED ADDRESS) R WRITE

RD

   E    N    I    L    T    I    B    A    T    A    D    R

RAM CELL LATCH

L SIDE READ DRIVERS

R SIDE READ DRIVERS

4

DUALL-PORT RAM Interrupt Logic L SIDE WRITE INTERRUPT TO R SIDE

L SIDE ADDRESS

ADDRESS = 3FF ADDRESS = 3FE R SIDE READ

L SIDE READ ADDRESS = 3FF ADDRESS = 3FE

R SIDE ADDRESS

INTERRUPT TO L SIDE R SIDE WRITE

5

DUUALL-PORT RAM Busy Logic ADDRESS (L)

DELAY BUFFER  DELAY BUFFER

ADDRESS EQUAL COMPARATOR 

ADDRESS EQUAL COMPARATOR 

CE (L)

BUSY (L)

ADDRESS (R)

CE (R)

L

R 

A

B

WRITE INHIBIT (L)

BUSY (R)

WRITE INHIBIT (R)

6

DUAL-PORT RAM Semaphore Logic DATA

CPU

L

R 

DATA I/O

DATA I/O

DATA

CPU

OR 

OR 

I/O DEVICE

"L"

ADDRESS

R/W

SEMAPHORE SELECT

L ADDRESS DECODER 

DUAL/PORT RAM MEMORY CELLS SEMAPHORE CELLS

R  ADDRESS DECODER 

ADDRESS

I/O DEVICE

R/W

"R"

SEMAPHORE SELECT

7

DUAL-PORT RAM Semaphore Logic8cell L D-LATCH L REQUEST

R D-LATCH

D

1

1

Q

L WR SEMAPHORE

D

R REQUEST

E

R WR SEMAPHORE

Q

E

GRANT (L)

GRANT (R) SEMAPHORE ARBITRATION LATCH

8