D8742 Просмотр технического описания (PDF) - Intel

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D8742

UNIVERSAL PERIPHERAL INTERFACE 8-BIT SLAVE MICROCONTROLLER

Intel 

8742

PROGRAMMING VERIFYING AND

ERASING THE 8742 EPROM

Programming Verification

In brief the programming process consists of acti-

vating the program mode applying an address

latching the address applying data and applying a

programming pulse Each word is programmed com-

pletely before moving on to the next and is followed

by a verification step The following is a list of the

pins used for programming and a description of their

functions

Pin

Function

XTAL 1 Clock-Input

Reset

Initialization and Address Latching

Test 0 Selection of Program or Verify Mode

EA

Activation of Program Verify Modes

BUS

Address and Data Input

Data Output During Verify

P20 – 12

VDD

PROG

Address Input

Programming Power Supply

Program Pulse Input

WARNING

An attempt to program a missocketed 8742 will result in severe dam-

age to the part An indication of a properly socketed part is the ap-

pearance of the SYNC clock output The lack of this clock may be

used to disable the programmer

The Program Verify sequence is

1 A0 e 0V CS e 5V EA e 5V RESET e 0V

TESTO e 5V VDD e 5V clock applied or inter-

nal oscillator operating BUS floating PROG e

5V

2 Insert 8742 in programming socket

3 TEST 0 e 0V (select program mode)

4 EA e 18V (active program mode)

5 Address applied to BUS and P20–22

6 RESET e 5V (latch address)

7 Data applied to BUS

8 VDD e 21V (programming power)

9 PROG e VCC followed by one 50 ms pulse to

18V

10 VDD e 5V

11 TEST 0 e 5V (verify mode)

12 Read and verify data on BUS

13 TEST 0 e 0V

14 RESET e 0V and repeat from step 5

15 Programmer should be at conditions of step 1

when 8742 is removed from socket

8742 Erasure Characteristics

The erasure characteristics of the 8742 are such

that erasure begins to occur when exposed to light

with wavelengths shorter than approximately 4000

Angstroms ( ) It should be noted that sunlight and

certain types of fluorescent lamps have wavelengths

in the 3000-4000 range Data shows that constant

exposure to room level fluorescent lighting could

erase the typical 8742 in approximately 3 years

while it would take approximately one week to cause

erasure when exposed to direct sunlight If the 8742

is to be exposed to these types of lighting conditions

for extended periods of time opaque labels are

available from Intel which should be placed over the

8742 window to prevent unintentional erasure

The recommended erasure procedure for the 8742

is exposure to shortwave ultraviolet light which has a

wavelength of 2537 The integrated dose (i e UV

intensity c exposure time) for erasure should be a

minimum of 15 w-sec cm2 The erasure time with

this dosage is approximately 15 to 20 minutes using

an ultraviolet lamp with a 12 000 mW cm2 power rat-

ing The 8742 should be placed within one inch of

the lamp tubes during erasure Some lamps have a

filter on their tubes which should be removed before

erasure

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