PLDTHIẾT BỊ LOGIC LẬP TRÌNH ĐƯỢC

(Programmable Logic Device)

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BOÄ NHÔÙ BAÙN DAÃN

Boä nhôù baùn daãn

Boä nhôù baûng Boä nhôù haøm

RAM ROM

tónh ñoäng MROMPROMEPROMEEPRO

M

PLD

PLA PALLCAPPALEPLPALEEPPAL

EPLD

PEELGAL

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BOÄ NHÔÙ ROM

Input: caùc tín hieäu ñòa chæ (Address)

Output: caùc tín hieäu döõ lieäu (Data)

A0

A1

An-1

D0

D1

Dm-1

INPUT(n ñöôøng)

OUTPUT(m ñöôøng)

Kích thöôùc ROM: 2n x m (bit)

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word line

bit line

101

1

0

0

11111

1

1

1

0

1

0

0

Baûng naïp ROM

A2 A1 A0

D3 D2 D1 D00 0

00 0 10 1 00 1 11 0 01 0 11 1 01 1 1

1 1 1 01 1 0 11 0 1 10 1 1 10 0 0 10 0 1 00 1 0 01 0 0 0

Caáu truùc noäi ROM 8 x 4 (bit)

1

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ROM 128 x 1 (bit) giaûi maõ 2 chieàu

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ROM 32K x 8 (bit) = 32KB

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Caáu truùc ROM coù ngoõ vaøo ñieàu khieån

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Coång ñeäm ba traïng thaùi (Tristate Output Buffer):

- 3 traïng thaùi (tristate): LOW / HIGH / HIGH impedance

- Traïng thaùi toång trôû cao (HIGH impedance): ngoõ ra hôû maïch

- Ngoõ ñieàu khieån 3 traïng thaùi:

* HIGH: The buffer is Active * LOW: HIGH

impedance

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Caùc EPROM thoâng duïng

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PLA (PROGRAMMABLE LOGIC

ARRAY)

INPUT(n bit)

OUTPUT(m bit)

k product term (soá haïng tích)

Daõy AND

Daõy OR

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Daõy AND coù theå laäp trình

Daõy OR coù theå laäp trình

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01

A Caáu truùc PLA 3 x 2, 4 soá haïng tích

B

C

C AB ABC

A B

A C

B C

A B C

F1

F1 = A B + A C + A B CF2 = A C + B C

F2

Baûng naïp PLA A B C F2 (C) F1

(T)1 0 -

A BA C 1 -

1 B C - 1 1 A B

C0 1 0

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PAL (PROGRAMMABLE ARRAY

LOGIC )

- Daõy AND laäp trình, daõy OR coá ñònh

- Caáu truùc PLA: soá ngoõ vaøo, soá ngoõ ra vaø soá coång AND treân 1 coång OR

- Moãi ngoõ ra laø coång OR coù soá ngoõ vaøo coá ñònh - Soá haïng tích khoâng söû duïng chung cho caùc ngoõ ra

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Caáu truùc PAL 3 ngoõ vaøo, 3 ngoõ ra, 3 coång AND / OR

1

2

3

4

5

6

7

8

9

I1

I2

I3

F1

F2

F3

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A

1

2

3

4

5

6

7

8

9

B

C

X

Y

Z

A A B B C C X X

X = A B + B C

Z = A B + B C + B C + A C

Y = A + B C= X + B C + A C

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X = A B + B C

Z = A B + B C + B C + A C

Y = A + B C

= X + B C + A C

Baûng naïp PAL

A B C X

OUTPUT

X = A B + B C

1 1 1 1

0 Y = A 0 0

+ B C

Z = X 1 0 0

+ B C 0 1

+ A C

123

456

789

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