MemoryROM, PROM, EEPROM

Mano and Kime

Section 6-6

Read-Only Memory

An example of implementing a function using a ROM

EPROMs, EEPROMs and Flash Memory

• EPROM– Erasable Programmable Read-Only Memory– Erase with ultraviolet light

• EEPROM– Electrically-Erasable Programmable Read-Only

Memory

• Flash Memory– Electrically-Erasable in bulk

Floating-gate avalanche MOS

Programming Erasing

EPROMs

Table 8.2Common EPROMs

Number Size2716 2K x 82732 4K x 82764 8K x 827128 16K x 827256 32K x 827512 64K x 8

27xx EPROM Pinouts1

2

3

4

5

6

7

9

10

11

12

8

19

20

17

18

15

16

13

14

21

22

23

24

GND

Vcc

A0

D0

D1

D2

D7

D6

D5

D4

D3

A10

A1

A2

A3

A4

A5

A6

A7

A9

A8

Vpp A11

2716 2732

__OE Vpp

__OE /

CE__

EPROM

27xx EPROM PinoutsVpp

2764 27128 27256 27512 27512 27256 27128 2764

Vpp Vpp A15

A14 A14 PGM ____

PGM ____

NC A13 A13 A13

__OE Vpp

__OE /

__OE

__OE

1

2

3

4

5

6

7

9

10

11

12

8

19

20

17

18

15

1613

14

21

22

23

24

25

26

27

28

GND

Vcc

A12

A0

D0

D1D2

A1

A2

A3

A4

A5

A6

A7

D7

D6

D5D4

D3

A10

A9

A8

A11

EPROM

CE__

Xicor X28C010 128K x 8 E2PROM

Xicor X28C010 128K x 8 E2PROM

10 ms