MemoryROM, PROM, EEPROM

Mano and KimeSection 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 101112

8

1920

1718

1516

1314

21222324

GND

Vcc

A0D0D1D2

D7D6D5D4D3

A10 A1A2A3A4A5A6A7

A9A8

Vpp A11

2716 2732

__OE Vpp

__OE /

CE__

EPROM

27xx EPROM PinoutsVpp

2764 27128 27256 27512 27512 27256 27128 2764Vpp Vpp A15

A14 A14 PGM ____

PGM ____

NC A13 A13 A13

__OE Vpp __OE /__OE __OE

1 2 3 4 5 6 7

9 101112

8

1920

1718

151613

14

2122232425262728

GND

Vcc A12

A0D0D1D2

A1A2A3A4A5A6A7

D7D6D5D4D3

A10

A9A8

A11

EPROM

CE__

Xicor X28C010 128K x 8 E2PROM

Xicor X28C010 128K x 8 E2PROM

10 ms