KYOTRONIC KC-85 User manual

SERVICE MANUAL
KYOTRONIC*
KC-85
PORTABLE COMPUTER
KYOSE! CO., LTD. OSAKA JAPAN

TABLE OF CONTENTS
PARTI INTRODUCTION ......... :
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1-2 External and Internal View ..
13 System Configuration .
1-4 Setting up
PART II MAINTENANCE PROCEDURE
Il-1 Disassembly
Il-2 Reassembly -
Il-3_ Installation Procedure of Optional RAMs and ROM
Il-4 Troubleshooting
PART III THEORY OF OPERATION .......
IlI-1 General Description . .
IlIl-2 CPU 80C85
Ill-3 PIO 81C55 .
Ill-4 UART6402......
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Ill-6 Address Decoding and BANK Selection
IlIl-7_ Memory Map
Ill-8 I/O Map and I/O Port Description
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TII-10 Cassette Interface .
Ill-11 Printer Interface ..
IlI-12 Buzzer Control Circuit
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IlI-14 Clock Control Circuit
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THl-16 LCD (Liquid Crystal Display)
III-17 Power Supply and Reset Circuit
PART V DIAGRAMS...........
V-1 Schematic Diagram
V-2 PCB Views
APPENDIX
A-l Connector Pin Assignment
A-2 Keyboard Layout
A-3 Character Code Table

i
INTRODUCTION

I. INTRODUCTION
In
this
section,
we
will
describe
the
system
over-
view
on
the
KYOTRONIC
85
such
as
external
and
internal
views,
system
configuration
and
set-
ting
up.
I-1 System Overview
The
KYOTRONIC
85
isa
light-weighted
Portable
Computer
which
has
following
features:
e Built-in application programs.
2-way
power
supply
by
dry
batteries
or
AC
adaptor.
e
80C85
Microprocessor
pin
and
software
com-
patible
with
intel
8085.
e
A-32K
Byte
ROM
which
contains
powerful
BASIC
interpreter.
©
Standard
16K-Byte
RAM
and
can
be
increased
up
to
32K
Bytes
easily.
Peripheral
I/O
Interface
such
as
for
printer,
RS-232C
and
cassette
recorder.
Built-in
Ni-Cd
battery
for
RAM
and
clock
func-
tion
back-up.
e
Auto
power
off
function
for
saving
the
battery
life.
I-1-1
Built-in
Apprication
Programs
BASIC:
The
principal
language
to
operate
the
computer.
TEXT:
This
function
is
a
simple
text
editor
for
creating
and
modifying
text.
TELCOM:
Telecommunication
function.
Terminal
emulation
of
file
up-load
and
down-load
features
through
RS-232C
interface.
[-1-2
2-way
Power
Supply
by
Dry
Battery
or
AC
Adaptor
The
KYOTRONIC
85
can
be
operated
by
4
dry
batteries
(Size
AA,
AM-3)
for
hand
held
carry
or
AC adaptor for office use.
Life
time
of
battery
operation
is
as
follows:
One
hour
per
day
....---ssee0%
Typical
20
days
Four
hours
per
day
.....-...+++
Typical
5
days
(Without
I/O
interface
at
normal
temperature)
I-1-3
Large
LCD
(Liquid
Crystal
Display)
Screen
The
LCD
has
240
dots
in
x-direction
and
64
dots
in
y-direction.
The
unit
size
of
the
dot
is
0.8
m/m
X
0.8
m/m.
User
is
available
to
change
view
angle
of
LCD
display
by
rotating
contrast
volume.
1-1-4 80C85 Microprocessor
80C85
is
software
compatible
with
8085
but
is
C-MOS
low
power
processor.
1-1-5
ROM
(Read
Only
Memory)
ROM
stores
application
programs
of
the
computer.
It
is
equipped
with
a
32K
ROM.
As
an
optional
feature,
extra
32K
ROM
can
be
installed.
Therefore,
by
doing
this,
capacity
of
ROM
is
ex-
tended
to
64K
and
user
can
use
them
separately
by
dividing
it
into
two
BANKs.
1-1-6
RAM
(Random
Access
Memory)
RAM
stores
BASIC
program
and
data.
Even
if
power
switch
is
turned
off,
the
contents
of
RAM
are
not
erased
because
of
recovery
by
back-
up
battery
equipped
in
the
computer.
The
com-
puter
contains
standard
16K
RAM.
As
an
optional
feature,
extra
RAM
up
to
16K
is
available
for
enhancement
by
installing
them
into
IC
sockets
on
the
MAIN
P.C.B.
Installation
procedure
for
optional
RAMs
is
shown
in
Section
II-3.
I-1-7 Peripheral I/O Interface
RS-232C:
Conforms
to
EIA
Standard.
Audio
Cassette
Interface:
Allows
to
use
audio
cassette
recorder
for
saving
or
loading
a
data
or
program.
Printer
Interface:
Conforms
to
Centronics
Inter-
face
Standard.
1-1-8
Built-in
Battery
for
RAM
Back-up
The
rechargeable
Ni-Cd
battery
supports
RAM
for
typical
20
days
(Standard
16K
RAM
installed).
This
battery
also
keeps
the
clock
function
when
the
power
is
off.
1-1-9 Auto Power Off
At
the
command-waiting
condition,
DC
power
is
automatically
cut
off
if
there
is
no
key-in
for
10
minutes.
To
re-start
the
operation,
switch
off
the
power
ON/OFF
switch
first,
then
switch
it
on
again.
The
value
of
interval
time
can
be
changed
by
software.

I-2 External and Internal View
LCD SCREEN
KEYBOARD
TOP CASE
AC ADAPTER JACK
BOTTOM
CASE
CONTRAST
VR
POWER SWITCH
Figure I-1 Front View
RESET PRINTER
SWITCH CONNECTOR
RS-232C CASSETTE RECORDER
CONNECTOR CONNECTOR
Figure I-2 Rear View

RELAY FOR CASSETTE
INTERFACE
Ni-Cd
BATTERY
oc/DC
cey
CONVERTER
X'TAL FOR
SYSTEM CLOCK
X'TAL FOR
CLOCK
OPTIONAL
STANDARD
STANDARD
RAM
RAM
ROM
Figure I-3 Internal View (1)
LCD PCB
(KEY BOARD)
SUPPORT
(KEY
BOARD)
PCB
Figure I-4 Internal View (2)

I-3 System Configuration
The
KYOTRONIC
85
can
be
connected
to
following
peripherals.
PRINTER
INTERFACE
CASSETTE
INTERFACE
RS-232C
INTERFACE
CASSETTE
TYPEWRITER
SYSTEM BUS
INTERFACE
EXTERNAL I/O DEVICE
Figure I-5 System Configuration

1-4 Setting up
Install four AM-3 type batteries or connect the
AC adaptor.
After installing the operational batteries or
connecting AC adaptor, turn on MEMORY
POWER Switch on the bottom case.
If the MEMORY POWER Switch is off, the
computer does not operate even if the power
switch is on.
Ni-Cd battery inside the case is used to protect
RAM.
Then, turn on the POWER Switch.
Following MENU will appear on the LCD
display.
Adjust the view angle by adjusting the CON-
TRAST volume so that you can set it at the best
position to operate the computer.
Figure I-5 Initial Screen

II. MAINTENANCE PROCEDURE

Il. MAINTENANCE PROCEDURE
This section provides information about regular
maintenance for the KYOTRONIC 85 such as
II-1_ Disassembly
Upper and lower Case Removal:
1. Disconnect the cables from the unit.
Taking care not to scratch any key top, turn
the unit over and remove the four screws 4
from the upper and lower cases.
Remove the upper case; it opens to the right
side.
Please note that the upper and lower cases are
secured by snaps. Also, do not apply too much
force when pulling open; the LCD and key-
board connectors are attached.
3. Remove the LCD, key board and LED con-
nectors from the MAIN P.C.B.
i)
LCD connector
LED connector
disassembly, troubleshooting chart and optional
ROM and RAM installation.
K/B P.C.B. Removal:
1. Remove the five screws 8) and then remove
the K/B P.C.B. and K/B supports.
LCD P.C.B. Removal:
1. Remove the buzzer connector from the LCD
P.C.B..
2. Remove the four screws (
the LCD P.C.B.
and then remove
MAIN P.C.B. Removal:
1. Remove the seven screws 0).
2, Remove the MAIN P.C.B. upward, taking care
when removing the RESET switch and battery
contact spring.
Buzzer connector
Key board connectors
Figure II-1 Disassembly
II-2 Reassembly
MAIN P.C.B. Reassembly:
1. Align the screw positions of the lower case
with the MAIN P.C.B. Gently insert the MAIN
P.C.B. from the rear and place the reset switch
knob in the proper notch.
2. Secure the battery contact spring.
3. Attach the MAIN P.C.B. to the lower case by
using the seven M3 X 8 screws.
LCD P.C.B. Reassembly:
1.
Attach
the
LCD
P.C.B.
to
the
upper
case
by
using
the
four
M3
X
3
screws.
2. Insert the buzzer connector in the LCD P.C.B.
K/B P.C.B. Reassembly:
1. Align the two K/B supports with the holes
in the P.C.B. and attach them so that they
fit to the P.C.B. edge.
2. Align the K/B supports and K/B P.C.B. holes
with the upper case screws.
3. Attach the K/B supports and K/B P.C.B. to
the upper case by using the five M3 X 8 screws.

CASE Reassembly:
1. Position the upper case to the right side of the
lower case, taking care not to scratch.the key
top,
2. Attach the LCD K/B and LED connectors to
the MAIN P.C.B.
3. Place the upper case over the lower case, taking
II-3 Installation of Optional RAMs and ROM
1. Installation of Optional RAMs:
Open the Top and Bottom Case of the com-
puter (refer to Part II-1 Disassembly and
Il-2 Reassembly). On the MAIN P.C. Board,
you can find two IC sockets marked “OPTION
RAM”. You must install the first 8K-RAM on
care that the cable is not pulled out of place,
Align the upper and lower cases so that the
tabs fit well.
Turn the cases over, and secure them together
by using the four M3 X 8 screws.
the IC socket marked “OPTION RAM #2”.
Prior to inserting the RAMs, make sure that
all the pins of the RAM are correctly aligned
against the socket pins.
Figure II-2 Installation of Optional RAM
2. Installation of Optional ROM:
Using the coin, remove the ROM Cover on the
Buttom Case. You will find an IC socket with
a plastic housing. Insert optional ROM into
this socket. On the P.C, Board, at’ the four
IC Socket for
Optional ee
cornérs of the IC socket, you will find the
number of pins, such as 1, 14, and 28.
Pay attention that pin-1 of the ROM is cor-
rectly aligned against pin-1 of the IC socket.
Figure II-3 Installation of Optional ROM

II-4 Troubleshooting
This section shows you how to go about solving
a problem or malfunction that has been identified.
All you have to do, is find the problem in the
Troubleshooting Guide and refer to the section
indicated by the number. Each section then
identifies the components associated with the
circuit in question and provides remedial instruc-
tions.
After completing any repairs, you should re-check
each functional item according to the CHECK
LIST. You can make use of the CHECK LIST
even if the location and condition of the mal-
function are not readily identified.
Note:
The
arrow
mark
(
—
)
in
this
Troubleshooting
Chart
shows
each
check
point
number
of
the
Check
Point
Location
Chart
(page
2-15).

TROUBLESHOOTING GUIDE
START
Doesn't work at all?
LCD doesn’t function?
YES
Keys don’t function?
YES
Buzzer doesn’t function?
YES
Clock doesn’t function?
YES
RESET doesn’t function?
Memory protection doesn’t function?
TO NEXT PAGE
2-4

Printer Interface doesn’t function?
Cassette interface doesn’t function?
RS-232C interface doesn’t function?
All functions check OK?

1. Doesn’t work at all
Check the power
© Check to be sure that the batteries are in and that the AC adaptor is
connected.
@ \s the memory power switch ON?
© Is the power switch ON?
Check the DC/DC converter circuit. > 1-1 (VL)
© |s 3,6—8V applied to pin 4 of the converter transformer?
(If not, check C2 ~ C8, battery contacts and adapter jack.)
© Check all output voltages.
a) VDD... +5V (if not, check D7, C15 and D6) > 1-2 (VDD)
b) VEE —5V (if not, check D4, C13 and RD5) — 1:3 (VEE)
c) VB. +5V (if not, check T15 and T16) > 1-4 (VB)
@ \s T6 oscillating? — 1-5 (76)
(If not, check T7, T8, C11, R19, R18, R20 and T6.)
Check the RESET and RAM RST signal.
© Is RESET signal high level (+2.2V —5.3V)?
If not, check T10, T11, T12, T9 RESET signal. > 1-6 (M19 Pin 36 RESET)
@ Is RAM RST signal low level (0.8V —0.3V)?
If not, check T10, T11, 712, T9 and RAM RST signal.
Check the logic circuit.
@ Check the CPU clock frequency.
(X1 terminal = 4.9152 MHz; CLK terminal = 2.4576 MHz)
(If not, check X2 and M19.)
@ Try replacing the LCD unit.
®@ Check all ICs,
—> 1-7 (M19 Pin 1)

2. LCD doesn’t function
NO
No display at all
YES
Check source voltage (VDD, VEE, VB).
Refer to (1) “Doesn't work at all’.
Check the RESET signal.
Refer to (6) “RESET doesn’t function’.
Check the LCD waveform.
(If
abnormal,
check
the
LCD
power
supply
operation
amplifier.)
Check the interface circuitry.
(Check all IC’s connected to the bus line, M17 and M20.)
Check if connector is correctly connected.)
Check LCD drivers (on LCD PCB) HD44102 and HD44103.
(Or replace the LCD unit.)

3. Keys don’t function
Check if keyboard connector is correctly connected.
Check the key scan signal.
Is scan signal present at M25 PAO — PA7 and PB1?
(If not, check if pulses are emitted from the TP terminal (pin 10) of M18 and
M285 at 4 msec intervals.)
—> 3-1 (M25 Pin 21 to 30)
—> 3-2 (M18 Pin 10)
—> 3-3 (M19 Pin 7)
—> 3-4 (CN7)
4. Buzzer doesn’t function
Check connector connections.
© Check if LCD connector is correctly connected.
© Check if buzzer connector on LCD PCB is correctly connected.
—> 4-1 (T19)
—> 4-2 (M26 Pin 13)
—> 4-3 (M34 Pin 4)
—> 4-4 (M25 Pin 34)
—> 4-5 (M25 Pin 6)
Check the buzzer.
2-8

5. Clock doesn’t function
Check the power supply voltage.
When power ON: +5V
@ When power OFF: 2.0 — 4.0V
(If
not
normal,
check
power
supply
circuit.)
—> 5-1 (M18 Pin 14, VB)
ae
Check
that
a
250-Hz
pulse
is
output
from
TP
signal.
— =F
Check
clock-setting
1Cs
(M14
and
M25)
and
ignal.
6. RESET doesn’t function
4 I
Check RESET circuit.
(Check T11, T10, T9, T12, DB, D9 and C17.)
—> 5-3 (M18 Pin 10, TP)
Check
oscillation
frequency
(F=32.768
kHz).
.
(If
not
normal,
check
X1,
C62,
C63
and
M18.)
—>
5-2
(M18
Pin
12)
Check
all
ICs
which
have
RESET”
and
RESET
signals.
(Check
M19, M25,
M22,
M14, M34,
and
also
check
LCD
unit
and
RAM.)

7. Memory protection doesn’t function
©
Check power supply voltage.
@
When
power
ON:
VB
=
+5V
(if
not,
check
converter
circuit)
—>
7-1
(VB)
@
When
power
OFF:
VB
=
2,0
—
4,0V
(if
not,
check
Ni-Cad
battery,
D2 and D18)
Check to be sure that there is not deviation in the timing of the signal and
that
the
level
changes
symmetrically,
when
the
RAM
RST
add
RESET
are.
—>
7-2
(T12,
RAM
RST)
switched ON/OFF.
Check CMOS RAM.
8. Printer interface doesn’t function
-> 8-1 (T18, STROBE)
> 8-2 (M14 Pin 2)
Check th data signals.
Check M25, M38 and M32.
Check the connector and printer cable,
> 8-3 (M25, 38, 32)

9. Cassette interface doesn't function
Check TXC signals.
{1s a modulated waveform output to pin 5 of the cassette connector during
program (DATA) save?
(If not, check M34, M19, C30 and C31.)
—> 9-1 (CN2, TXC)
Check RXC signals.
|s a digital waveform input to the SID terminal of the CPU during program
(DATA) load?
(If not, check D11, D12, 013, M37, M34 and M19.)
—> 9-2 (M19 Pin 5, SID)
Check the cassette connector and cassette cable.