Sharp Pc-4741 User manual

-

PC-4741

SHARP

SERVICE

MANUAL

CODE: OOZPC4741SM-E

PERSONAL COMPUTER

PC-4741

PC-4721

MODEL PC-4702

;------------

CONTENTS

-------------..

CHAPTER

1.

OVERVIEW

.....................................

1

CHAPTER 2. GENERAL INFORMATION

.........................

3

CHAPTER 3. MAIN BOARD OPERATION

.........................

7

CHAPTER 4. LCD UNIT

......................................

23

CHAPTER

5.

POWER SUPPLY CIRCUIT

........................

25

CHAPTER

6.

HARD DISK

....................................

27

CHAPTER 7. FLOPPY DISK DRIVE

............................

31

CHAPTER

8.

SERVICE-MAN DIAGNOSTIC . . . . . . . . . . . . . . . . . . . .

..

33

CHAPTER 9. APPENDICES

...................................

47

CHAPTER 10. CIRCUIT DIAGRAM &PARTS POSITION

............

66

SHARP CORPORATION

This

document

has

been

published

10

be

used

for

after

sales

service

only.

The

contents

are

subject

to

change

without

notice.

CHAPTER 1. OVERVIEW

1. Scope

This manual

is

covered for PC4702, PC4721, PC4741 CPU and hard

diskdriv9.

For

detailed

information

on

other

auxiliary

equipment

and

options

(list

following),

please

refer

to

the

separate

service

manuals

provided

for

each

devices.

CRT adaptor (CE-471A)

MFD unit (CE-452F)

EMS card (CE-471

B)

SID card (CE-451

B)

2.

Service method

1)

Cabinet

Top

Removal

1.

Before

disassembly,

remove

the

AC

adaptor

and

the

built~in

lead battery.

If

the

CRT

board,

the

modem

board,

or

the

SIO

board

is

installed,

locate

the

face

plate

screw

fastened

to

the

computer

and

remove.

2.

Remove

the

eight

screws

on

the

computer's

bottom

panel.

'f

'"

3.

Lift

up

the

cabinet

top.

This

reveals

the

system

board

of

the

computer.

_1-

-

PC-4741

4.

Lift

up

the

keyboard

and

unfasten

the

connector

as

illustration

shows.

The

disconnect

the

cable.

Key Board Cable

Key

5.

First

incline

the

cabinet

top

backward

slowly

about

30

degrees.

Then disconnect three cables. (the LCD signal cable, the LCD

backlight cable, and the LED cable.)

2)

LCD

unit

removal

LCD Signal Cable

LED Cable

LCD Backlight

Cable

1.

Remove

the

four

screws

which

are

fixing

the

tilt

mechanism.

2.

Move

a

tilt

mechanism

to

the

center

with

a

screwdriver,

and

remove

it

upwards.

Then

remove

the

other

tilt

mechanism

in

the

same

manner.

-

PC=lfT4F

s

..

Operate th·"tCD.

r"leas~'leite"

'unfix;tns

;upper

cabinetand the

LCD section, and separate,the upp-et:cafjinef:from';the LCD

section.

-~'.)

,,--

.'J

In

this

case,

be

careful naHa damage

tw~

LCD

cables.

Installation

1

..

,

Inst~1I

the upper,cabhlet

9n:d-1h~-lCD-,$e6ti,on

by

reversing the

.

,di5ass~mbly

proceq.LJre~:

'_,

_ :

_._~_

_ "

'When

installi~g

the)l~.mechanisrill·

~!3itl:1e_

-Shi~,tt

horizontally

in

.parallel

t?-

th~

ang~e

bott~m

and insert into the,LCD section.

2. Attach,

t~7'

l:Ipper and lower cabinets to the set.

3) LCD section

Disasse'mbly

For disassembly of

the

LCD

u,nit

j

1;18

su're-

to

.follow

the

procedure

below. If not, the cabinli:!lmay be damaged.

1. Remove the' keyboajd.

2. Separate the upper-cabinet

!rom

the lower cabinet.

3. Remove the uppercabinet.

4. Remove the four rubber cushions fixed with duplex tape on the

LCD.seqtion, andremove the four screws which were covered

by

the four rubbe(cushions.

-2-

5. Remove the fronfanci"r'ear-c.abihets

6f.the~LCD€fedti911.

-,

._

6. Remove the fixture which fixes the LCD section and the body.

7. Remove the reflection plate ofthe backlight.

S.

Remove the fixing screws and the connectors

otthe,

'.ilh)mil}~

tion control PWB and the backlight convertor PWB, and

. remoV"the PWB·s.

Assembly

1. Assemble the'

Lbb

urilt-

by

reversing

.the:

disa5's~mbly'

proce-

dure': ' .

..,

1 __ .

__

.",

Carefully check that there is no fingerprint on the LCD'secllon.

If there is, clean with a cloth and

a1cohQI.

:111e

cloth must,be

fine and smooth, such as glass wiper

dOt·~.

..

.

'-,

...

2. Attach the upper cabinet to the set.

3. Attach the lower cabinet to the set.

4. Attach the keyboard to the set.

s.

HD

INTERFACE AND

HD

DRIVE

The HD drive unit can be replaced only in whole unit, but not

in

part. When they are diagnosed to

be~A~fe9ijve

bytfrediagi1qs-

tic program, replace the whole unit

of

them.

4) Cautions

1. Although the CE-471A CRT adaptor board is an

aption!ar

the

PC-4700,

it

pomes

standard for

the.

US version

pC4ipo.

For

more information aboutthe

Wiring"

schematics and parts layout.

",ferto

th,,·CE471A

Service ManUal. '

2. Cosmetic sheet

Do not use the cosmetic sheet once removed.

Be

sure to use

the new one.

3. Deposit

of-

a paint dust on the back

of,

the

cabine~

may

fallon

the

P;WB

when the machine is disassembled' and re-as-

sembled for servicing and it

may

then cause a machine mal-

function.

To·avoidthis,the

machine internal must be cleaned

whenever the machine is

disassembled~

CHAPTER2.GENERAL

INFORMATION

1. General information

PC-4700 series

are

compact and lightweight laptop computers. They

pack

the

power

and

sophistication

of

desk-top

models

into

the

laptop

size.

In

order

to

attain

the

high

performance,

this

computer

accommodates

large

and

high contrast paper white

LCD

with

the

CCFT backlight,

3-1/2"

floppy

disk

drive,

3-1/2"

hard

disk

drive,

and

well-packed

79-

key

full

keyboard.

The

display

provides

clear

text

and

graphics

in

640

by

400

dots

especially

by

supporting

4-shades

of

gray

(tiling)

and

8 x

16

dots

(character

box)

characters.

Further,

PC-4741

or

PC-4721

incorporates

a 40MB

or

20MB

hard

disk

drive

in

its

unit

and

accomplish

battery

operation.

The

full-siza

step

keyboard

provides

79

keys,

enhancing

the

ease

of

use

with

separate

function

and

cursor

keys.

The

main

unit

includes

iB0188

compatible

CPU

running

at

10MHz,

socket

for

coprocessor,

640KB

RAM

standard

expandable

to

1.6MB,

a

serial

interface,

a

parallel

printer

interface,

an

external

FDD

inter-

face.

The

internal

options

include

modem

card

with

a

serial

interface

(for US/Canada only), color/monochrome

CRT

adaptor, and t

MB

EMS

memory

card.

The

external

expansions

include

5-1/4"

360KB

floppy

disk

drive

unit.

The

newly

revised

original

BIOS

assures

the

execution

of

numerous

applications

with

the

combination

of

MS-DOS

3.3

operating

system.

PC-4700

series

consists

of

the

following

3

models:

~PC-4702:

640KB

RAM;

two 3-1/2" t .44MB FDDs; display w/ back-

light;

79-key

keyboard;

serial

interface;

parallel

interface;

external 5-t/4"

FDD

(360KB) interface; MS-DOS

3.30/GW-BASIC 3.22

~PC-4721:

640KB RAM; a 3-1/2" 1.44MB

FDD;

a 20MB HDD; dis-

play

wI

backlight;

79-key

keyboard;

serial

interface;

paral-

lel interface; external 5-1/4"

FDD

(360KB) interface;

MS-

DOS

3.30/GW-BASIC 3.22

~PC-4741:

640KB RAM; a 3-1/2" 1.44MB

FDD;

a 40MB HDD; dis-

play

wI

backlight;

79-key

keyboard;

serial

interface;

paral-

lel interface; external 5-1/4"

FDD

(360KB) interface; MS-

DOS

3.30/GW-BASIC 3.22

-

PC-4741

-3-

--------~¥f~4¥~~c~=.---------------------------------------------------------------------------

2.

System Configuration

2-1.

System

block

diagram

2-1-1. PC-4702

2-1-2. PC-4721/4741

1

ROM (64KB)

RAM (640KB)

CE-452F

'I

5-1/4" . 360KS FOD

,-------,

Keyboard

LCD (640 X 400)

wlbackUght

t'C~:';7'1S'-'"

: MS-DOS ,

i_~~:~~~~~j

M,anuaJ

:

IndIcates

options

;

CE-471S

:

MS-DOS

•

i

_~~:~~_~I.~.:

Manual

Parallell/F : Printer :

(Centronics) ,

----~-._

••••

-.-

••,

1

.t~~<?!'1.~~~~

_~~Iy!

~.

__

:.:.

..

_____

>

Telephone

line

:CE-462M Modem:

","

---~----:card

W/SIO

~---:-'.---.-:o-

RS-232C peripheral

I/O

iSlot;:::::::::::::::::

_:'

:

or:

CE4518

~---/;'--">RS-232cperipheral

----·i

....

~!<?_~~~~_

..

: T

.....

>

RS-232C

peripheral

.;;;

;,~;-i::

~~t~~~~;:;::,

--

-

~IT::·ttt;t:~;::

".

CAT :

jMDA

.............

.

1

i

or

:"CE471ii

........

:

EMS

4.0

card

,.................

(1MB)

--.-.-.-.-------.-.---~

Indicates

options

-4-

!.

-

~--.'

;'.,.

-

PC-4741

External 5-1/4" FDD (360KB) x 1 port (D-SUB 25

2-2. Specification

2-2-1. Main unit

.~

__________

pin,

female

connecter)

CPU

NEC V40 (i80188 compatible)

CPU

clock speed -10MHz

(7_16MHz

when

coprocessor

is

installed.)

System

speed

-

Standard/Slow

selectable

on

set-up

menu

Coprocessor Socket for i8087-1

(1

OM

Hz version)

NOTE: CPU clock speed

is

changed

to

7.16MHz

automatically

when

coprocessor

is

installed.

When

it

is

removed,

CPU

clock

speed

is

changed

to

1

OMHz

automatically.

Memory

ROM

-64KB

including

BIOS,

set-up

functions,

eG,

self

check,

etc

512K bits EP-ROM (27C512 type) x 1 piece

ROM-8KB (HD version only)

including

HD

BIOS 64Kbits EP-ROM (27C64

type) x 1 piece

RAM

-640KB standard

256K bits (64K x 4 bits)

DRAM

x 4 pieces

1Mbits (256K x 4 bits)

DRAM

x 4 pieces

without

parity

expandable up to 1.6MB with the optional 1

MB

EMS

memory card (EMS

4.0)

VRAM-128KB

Display TST (Triple Super Twisted nematic)

LCD

with one

CCFT (Cold Cathod Flouecent Tube) edgelight

Text

-

80

char.

x

25

lines,

8 x

16

dots

char.

Box

Graphics -640 x 400 pixels, 4-shades of gray (tiling)

Aspect

ratio

-1:1

Emulation -CGAlMDAlAT&T 640 x 400 Graphics

LCD active area -205(w) x 155(h)

mm

LCD contrast and backlight brightness are adjus-

table by each volume

Notdetachable

90

-131

degrees tilt angle adjustment

CCFT backlight

-

white

color

-life: Approx. 10,000 hours (until luminescent

brightness becomes

halD

can

be

replaced

by

service

man

(service

parts)

Data

storage

: PC-4702-

two

side-mounted

3-1/2"

1.44MB

FDD

Right

side:

A

drive,

Left

side:

B

drive

Keyboard

-Interface

PC-4721/4741 -one side-mounted 3-1/2"

1_44MB

FDD

one internal 3-1/2" 20MB/40MB

HOD

Left side:

HOD

(C

drive),

Right side:

FDD (A

drive)

HDD

-

average

access

time:

29

msec

power

save

management:

can

be

set

"Time-Out*"

on

set-up

menu

Always

ON/2

minutes/5

minutes/10

minutes

:1::

spindle motor of

HOD

will be control-

led by the value of "Time-Out"

full-size 79-key step keyboard

separate

cursor

keys

10

programmable

function

keys

LEDs for Num Lock, Scroll Lock, and Caps Lock

Set-Up

key

for

pop-up

set-up

menu

Cylindrical and thin keytop

With

click

mechanizm

Not detachable

Serial (RS-232C) x 1 port (D-SUB 9 pin,

maleJX>D,

nector)

Parallel (Centronics) x 1 port (D-SUB 25 pin, female

connector)

-5-

lIO

slot

Sharp

proprietary

slot

x 3

-1

slot

for

color/monochrome

CRT

adaptor

- 1 slot for modem/SIO card (for US/Canada only)

or

SID

card

The

above

cards

are

installed

into

the

same

space.

So,

only

one

card

is

available

at

the

same

time.

-1

slot

for

1

MB

EMS

4.0

memory

card

Power Supply: Rechargeable lead battery

-

low

battery

warning

low

battery

indicator

alarm

AC adaptor

EA-452V

IN

local voltage

OUT

DC

9V, 2.5A

Dimension 115(w) x 67(d) x 55(h)

mm

Weight Approx. 425g

Volume

LCD

contrast

volume

Backlight

brightness

volume

Switch

Power

ON/OFF

button'

(software

switch)

4

dip

switches

Dip Switch Label

Feature

Initial

setting

Alarm

Control

1 (Low BatterylShut off Alarm) ON

ON/OFF

2

Speaker

Control

ON

(without alarm) ON/OFF

3 System all reset ON/OFF OFF

4 SpeakerVolume LOW/HIGH OFF (HIGH)

Shut

off

alarm

switch

(alarm

when

upper

cabinet

is

shut

during

power

on.)

LED

indicator

:

Other

Dimension

Weight

Software

Manual

Power (green); low battery (red);

PC-4702 -

drive

A (green); drive B (green)

PC-4721

14741

-floppy disk (green); hard disk

(green)

Caps Lock (green); Num Lock (green); Scroll Lock

(green)

Carrying handle; speaker; display lock slide-switch x

2

11

(w)

x

11.1

(d) x

2_2(h)

inch

280(w) x 282(d) x 58(h) mm

(high:

cushion

rubber

on

the

bottom

cabinet

in-

cluded,

without

cushion

rubber:

57mm)

PC-4702-3.6kg

PC-47?1/4741

-3_8kg

(with battery, without AC adaptor)

battery: Approx. 830g

AC adaptor (EA-452V): Approx. 425g

MS-DOS 3_30/GW-BASIC

3_22

Operation Manual (MS-DOS/GW-BASIC quick refer-

ence

included)

Optional MS-DOS and GW-BASIC manuals

-

--------=~~~~4M~~-----------------------------------------------------------------

Internal

Options:

~.

CE·471

A

color/monochrameCRTad~ptor.

-

color/l1)~mC?_chrC!ITIe

2

m~~~~-.$,uppo~ed:

"

colo(:CGA(640,~209pi~els).

;,

monochrome:

MDA

(720

x

350'pix~ls)

, .

C?P'9~!~or'}02h,rom.~

l!Iode

j~

~f1!~¢e~

by:

~e~-up

functions.

-

2:,sh~racter

sets

(CG1!9<;3,,)

supported

CG1:gen

era

k:,

,

."

CG2:

Denmark/Norway

.'

,.

, .

CG1/CG2

is

selected

bYShort'pin

switch

on

ihecarci: '

dealer

option

...

:_'---"...-

..

.:..

--

-'

J:

',.

~

CE·451

B

SIO

card

-

Serial

(RS·232C)

x1port

(D·SUB

?§piQ"

1)1~'e

connector)

-

dealer

option

'-i>

'.

NOTE:

Max.

SI02

po~rts.ay.ailable

when

CE:451

B

installed.

1.

Stanc!ar~SIQ(/)·SUB

9pin,

mal~,qonnector)

,2.,.SIO,p.nJhe,pptionai

CE'~5~B

SIO

card

(D·SUB

25pin,

mal~,.c\:mne.ctorL

CE-471

B

EMS

memory

card

, ,

-

1MB

EMS

4.0

memQryeard

and.EMS4.P,soitware

-

with

OP€!f~~onmcln~_al,

_"

-

dealer

option'

.

CE·462M

modem

card (for

US/Canada

only)

~

ri'lIjci~/S_IO

2.

functions

~lip'Rorted

mode:

300/1200/2400

BPS;

Bell

103l212A;

CCITT

V.21

,

V22

and

V.22,

bis

Hayes

compatible

command

set

SlO:-RS·232C x1port

(D·SI,I~25

pin,

male

connector)

modem/SIO

function

is

se1ectE!9,QY

set~up

functions

-

;dealer

option

-

'with

installation

instrudions

NOJE:.M'IlUl{C;l',2

porj~avaliabJ$:When

CE·462M

i$

installed

,and,us~d:

asa

510,

' " . ,

1.

Standard

SIO

(D·SUB

9

pin,

male

connector)

2,

SIO

on

the

optional

CE·462M

modem

card

(D·SUB

25

pin,

male

·c?nnectorj· ,

Extem,aJ,ppti,?ns:

;

,I.

,

CE·452F

5·1W

FDD

unil

(without

SEEG)

-5,114"

~DD

(360KB)

x 1

-ACpower

-

with

I/F

cable

Manual:

CE·470KElFIWIMIS

key.fdp

kit -

-

key

top

(E:

18,

F:

21;

W:

19,

M:

19,

S:

24

pieces)

-iodlforpullirig

up

the

key

t6p

CE-470SElF/Gil·dp~ration·n\8J1Jal

-

operation

manual

for

PC4700

series

(E:

English,

F:

French,

G:

G~rman;

I:

italian)

NOTE:

PC·4700

forSEES doesr't

indludeiheop~ration

manual.

.

\;.'

"!):'ij

; )

oj,

) ,

J"

,,;- ,

'"

1)1"

'~',

'

-6-

.....

I

'2

r·····

-:

HID

: ROM

.2

'------

RS22C

I/F

I

9pin

I

SLOT

(AI

I I

ocv,

\0,

~

20,~~z

14.3,);',MHz

I CE-471A I I CE-451B 1,.8432

~

rD'J

riDh

I . .

CE-462M

I

MHz

ADO-7F I

II

• -

~-

---'

INSS2C50A

X1~~::::::~~~~~~~~~~.§!~~~50;P,"~I~I~

~~~1'34~p;~n~i

~~D~~~UA;R~Tl;;~~;j

AS-19 A ILIl=f I

1m

D

---'

(JPD7020B-10

_______________

: ('21

~

~------

~

=

:~

Opt;onal

i-.-

I-

I

'------'

HD

Co-Pm,e.,o,:

LZ95H12

-----,

8071-1

~

(Gale

array)

---

...........

:

Video

BIOS

ROM

I--

DRAM

-LZ93J21 FDC

(64KB)

1=

(12BKS)

(Gale array)

,......

_____

. 27C512

I+-

16MHz

~

.S

.

256Kbn

X4

~

TCS566F

~.

I

____

, l

System

I--

f--

L~M~U:XJ------I

DRAM

F=

(640KBI

[+-j

Hf--I--~

~

1MbilX4

r-

256Kbit

X 4

,

______

. I

Dd,e'

i

f=='

I

('11

"d

disk

with

interface

iSLOT

(CI

i-----J 3.S4MHz

~

-System/Key bo",d

~

3.5 ;n,h

! CE-471B

~

-RTC

~

floppy disk drive

I 32.76SKHz g I

1.44MB

. 34p;n L Conlmlle,

'7

L D .

.---'---

1.

______

,..;

LU57S44P

/

AMP

,,,e,

l Driver 1

,

----r~Wh1

VCC

L 25p;n

'\

r--:

~

_

VGG

r:::L-----c

r:::::::,

Pr;nte,IIF

Power

supply

VCRT

r--~

LCD

unit

f--

Keyboard

SPEAKER

640

X 400

GND

_

'-

______

----1.,2V

(~1)

PC-4702: 2

drives

PC-4721/4741 : 1

drives

(·2) PC-4721/4741 only

mlo

rl::E:

OIl>

o "tI

'"

-I

t:I

m

;;: :xl

G>

(,0)

JJ

I •

>3:

21:l>

1-

Z

III

o

l>

:xl

C

o

"tI

m

:xl

~

o

z

21

;;;:!

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-

--------~F~~r.------------------------------~----~------------------~-----

3-1. Memory and I/O map

3-1-1. Memory

map

for

the PC-4700 system

FFFFFh

r------,

ROM-BIOS

FOOOOh

\-----\

E7FFFh

EOOOOh

DOOOOh

C9FFFh

CeaaOh

BFFFFh

BBFFfh

88000h

BOFFFh

BOOOOh

9FFFFh

ooaDah

EMS

window

HD

ROM

BIOS

System

Rsvd

eGA

Video

Memory

System

Asvd

~QA

Video

Memory

Standard

Main

Memory

: 640KB

20000h

Fig.

3-1

Overall memory

map

3-1-2.10/MAP

Register,

Emulate~

DMA

Controller

V40DMA Controller

Interrupt Controller

System Timer

PPI

NMI

Mask

Asynchronous Communication (Secondary)

Hard Disk

Parallel Port

VIDEO

10

VIDEO

10

VIDEO

10

VIDEO

10

FLOPPY DISK

10

Asynchronous Communication

(Primary)

V40

System

10

3-2.

Clock

generator

:

maximum

768KB

EMS

Memory

(1MB)

10

Address.

OOHnOFH

10HnlFH

20Hn3FH

40H

..

5FH

60H

..

62H

AOHnBFH

2FBHn2FFH

320Hn323H

37BH

..

37FH

3BCH

..

3BEH

3BOH

..

3BBH

3BFH

3COH

..

3CFH

3DOH

..

3DFH

3FOH

..

3F7H

3FBH

..

3FFH

FFFOH

..

FFFFH

The

cloc)~

generator

is

includetfin~bZ95H-1·2.-·and-~nnecte'd

with-tWo"~--~

crystal oscillators of

14.3181

BMHz

and

20MHz.

The

two

clocks pass through

the

clock select drcuil

in

LZ95H12,

and

one of them is outputted from

Xl

terminal to

V40·

Xl

termi,liar.

,The

details are

shoWn

in

Fig.

3-2.

~Ji-

20MHz

CEoseD._

-

"-

~

-

=

CPOSC1

Clock

-X1· .

X1

14.3181BMHz

select

NC'X2'

V",

OSCD

circuit

= aSC1

Bus

cycle

CPUCLK

CLKOUT

LZ95H12

generator

SYSCLK

Fig.

3-2 Overall clockgenerate circuit

The frequency

\If

,he

clo¢k

~ypplied

from

LZ95H12

Xl

terminal

to

V40

is

determined according

to

the

states of bit 3

(OSCSPD1)

and

bit 2

(OSCSPDO)

ofthe

10

port

(7BH)

in

LZ95H12

as

shown

below.

7654320

X X X X \x\x 107BH(RIW)

a

20MHz

Assertion of

the

RESET signal will reset

OSCSPD

[0

..

1]. IF

BOB7

is

not installed, ROM·BIOS sets

OSCSPOO.

When

setting

OSCSPDO,

the shift to frequency of

10MHz

is

made

wtth

no

!;Ittches, thus avoiding

the

need

to

reset the

system.

3-3.

~eset

circuit

SCM

(LU57844)

R

ET

LZ95H12

l.Z93J21

RES

TCS566F

OUT

'

B2C5OA

V

CN7-28{34-pin

slot)

CN8-49{CRT

connector)

eNS·1

(HOD

connector)

Fig.

3-3 Reset control circuit

The

SCM

can

be

reset

in

one of the following two

ways.

1.

When

VGG

turns on, a high state

of

signal is sent

to

the

line

ACL

of

the

SCM

from the differentiation circuitry

composed

of a

capacitor

and

resistor.

2.

When

the

dip switch-1.located at the lower

side

of

the

machine,

set

ON,

it causes the

ACL

input

high

to

reset

the

SCM.

Operation

starts

when

it turned off.

With

depression of the ON/OFF switch while

1he

machine

is off or a

hardware reset is given (simultaneous

depres'sion

of

CTRL,

AL

T,

SETUP

keys),

VCC is turned active

and

RESET is

forced

high.

The

V40

synchronizes

an

async signal RESET

with

the internal clock

and

sends it out

as

an

active high signal.

The fdrmer (RESET) is sent

to

the

V40,

and

the

latter

(RESET)

to

the

LZ95H12,

LZ93J21,

TCB566F,

B2C50AV,

34'pin slot,

CRT

connector.

The

RESET

signal is inverted

and

sent

to

HDD

connector.

3-4. Interruptcontrol

Eight maskable interrupts

and

one non-maskable interrupt

are

provided. .

NMI

is

set highby the LZ95"'12 when a

sp~cific

VO

is accessed.

• Maskable interrupt

may

be

caused

in

one

of

the

following:

Numbe:r

Usage

Originating device

1

KeyboarQ

LZ95H12

3 Asynchronous communication

(Secondary)

INSB2C50A

4 Asynchronous communication

(Primary)

5 Hard disk

Hard

disk controller

6 Floppy disk

TCB566F

7 Parallel printer

LZ93J21

3-5.

Bus

configuration 3-6. Memory -

PC-4741

~~~D~~.~orDlWmgJwnbul's.~s~

________________

~~~~~~~

____________________________________

__

1)

CPU

(AD)

bus

3-6-1. Block diagram

2)

System

Data

(SO)

bus

The

bus

configuration

is

shown

in

Figure

3-4.

V40

ADO-A;e0c-'

-.II\~

ROM

(BIOS)

DRAMS

(640K)

--"-':; 808:

"'--"1':

(optIOn)

1-_-;l'I-'S",AO:.-=SA.:.:':,'

II

Other

,--,\It'-;==:;"\J

Devices

500-507

LZ95H12

Fig.

3-4

Bus

configuration

3-6-2.

LZ95H12

address assignment

RAS

and

CAS

are

generated

from

LZ95H12.

RASO

is

set

active

if

RAS

is

even

address

or

RAS1

active

if

RAS

is

odd

address.

CPS

signal

is

assigned

to

C'ASl5

-

CAS4

as

shown

in

Table

3-1.

Table

3-1

Input

A19

A1B

A1l

A1B

AO

mAll

RASO

RAS1

CASO

X X X X X 0 0 0 1

, 1 1 1 X 1 1 1 1

0 0 0 X 0 1 0 1 0

0 0 0 X 1 , 1 0 0

Neither

of

A19

-A17

is

X 0 , 0 1 ,

"0"

X 1 1 1 0 1

-9-

v40

1

'--

________

,

ADO-AD7

64KX4X2chlp

64KX4X2chip

Fig.

3·5

RAM

section

block

diagram

Output

GAS'

GAS2

CAS3

i;AS4

ROMCt

1 1 1 1 1

REFRESH

, 1 1 1 0

FOOOOH-FFFFFH

, 1 1 , 1

OOOOOH-1

FFFFH

even

, , 1 , ,

OOOOOH-1

FFFFH

odd

0 , 1 1 1

20000H-9FFFFH

even

0 1 1 1 1

20000H-9FFFFH

odd

Sharp PC-4741 User manual

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