Canon Cat Operating instructions

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0002 of 0187
IAI / JEF RASKIN INFORMATION
Canon Cat Computer
Repair Manual
Canon

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0003 of 0187
callDlI
The·~·"~~--Plot~~··
(
, -
JULY 1987
~.
Can 011
NY8-1360--000
\-
-.-
~ <Cl 1987 CMIII lit. I'MI CIt lEU a, 1987 PIIII1BI .. M. I~,..... _.
... , "
l ~. .
i .; : .

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0004 of 0187
TABLE OF CONTENTS
CHAPTER 1 GENERAL
Page Page
1-1. Specifications .................................... 1-1
1-4. Block Diagram ................................. 1-4
1-2. Overview ........................................... 1-2
1-5. Block Diagram Description ............. 1-5
1-3. System Overview .............................. 1-3
1-6. Connector Layout ............................. 1-9
CHAPTER 2 THEORY
2-1. Address Map .................................... 2-1
2-3. Circuit Description........................... 2-4
2-2. Initial Flochart .................................
2-2
CHAPTER 3 REPAIR
3-1. ILFDD Unit ...................................... 3-1
3-4. CPU PCB Unit................................. 3-35
3-2.
CRT/Power Supply Unit 3-5. Keyboard Unit.................................. 3-44
(MATSUSHITA).............................. 3-17
3-3. CRT/Power Supply Unit
(GOLDSTAR)..................................
3-25
CHAPTER 4 CHECK OPERATION
4-1. Program Name ................................. 4-1
4-2. Check Range/Specification .............. 4-2
4-3. Operation .......................................... 4-4
4-4. Check Points for
OK Results.......... 4-9
4-5. Concrete Examples
of NG Results .. 4-12
4-6. ROM Check Sum Table .................. 4-20
I

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0005 of 0187
PARTS CATALOG
Page Page
How to Use Parts List .......................... i -
ii
C-12. Keytops
A. Assembly Location Diagram ........ A-I
(DENMARK) ................ C-29 -C-30
B. Assemblies .......................... B-1 - B-2
C-13. Keytops (SWEDEN/
C-l. CPU PCB Unit .................. C-l -C-6
FINLAND) .................... C-31 -C-32
C-2.
CRT/Power Supply Unit C-14. Keytops
(MATSUSHITA) ............... C-7 -C-8
(NETHERLANDS) ....... C-33 -C-34
C-3. Power Supply Unit .......... C-9 -C-IO C-15. Keytops
C-4.
CRT/Power Supply Unit (W.
GERMANY) .......... C-35 -C-36
(GOLDSTAR) ............... C-li -C-12 C-16. Keytops
C-5.
CRT/Power Supply
(SWITZERLAND) ........ C-37 -C-38
PCB Assembly ............... C-13 -C-16 C-17. Keytops
(FRANCE) ...... C-39 -C-40
C-6.
MICRO FDD Unit ....... C-17 -C-18 C-18. Keytops (U.K.) ............... C-41 -C-42
C-7. Keyboard Unit ............... C-19 -C-20 C-19. Keytops
(SPAIN) ........... C-43 -C-44
C-8. Keytops
(USA/CANADA/ ASIA/
C-20. Keytops (ITALY) .......... C-45 -C-46
OCEANIA) .... C-21 -C-22 C-21. Keytops
(S.AFRICA) .... C-47 -C-48
C-9. Keytops (QUEBEC) ....... C-23 -C-24 C-22. Keytops
(JAPAN) .......... C-49 -C-50
C-IO. Keytops
(LATIN) .......... C-25 -C-26 D. Screws .........................................
D,E-l
C-II. Keytops
E. Tools ........................................... D,E-l
(NOR WAY) ................... C-27 -C-28 F. Numerical Index ...............
F-l -F-24
I

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0006 of 0187
\,
'",'
.. ~ ,
Page
1-1. Specifications ..............................: ...... 1-1
1 .. 2;, OverYiew ... :........................................ 1-2
1-3. System Overview ......................:......... 1-3
, t'
-:
" " Page
,1-4. Block Diagram .................................. 14
1-5. Block J)jagramDescription .. ;........... l~'
1-6. Connector Layout ........................... ::. '1 .. 9

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0007 of 0187
1. GENERAL
1-1. Specifications
SYSTEM CONFIGURATION
Standard Configuration:
Memory:
Floppy Disk:
Disk Capacity:
DISPLAY
Screen Size and Type:
Color:
Format and Capacity:
Underline Display:
Centering Display:
Cursor Position:
KEYBOARD
Number of Keys:
Entry System:
Keytop.
GENERAL FEATURES
Line Spacing:
FUNCTIONS
Cursor Movement
Leap Forward
Leap Backward
Leap Again
Local/Global Leap
Leap-Erase
Creep Forward
Creep Backward
Screen Scroll-Leap
SOFfWARE
POWER SUPPLY
OPERA TION ENVIRONMENT
Temperature:
Humidity:
OIMENTIONS
WEIGHT
SUbject to change without notice.
CRT + Keyboard + Micro FDD
256K
3.5" single-sided, double-density, double-track
240K (text: 180K, about
80 pages)
9" CRT
Black-an-white
24 lines
by 80 characters (344 by 640 dot)
Standard
Standard
LEAP,
CREEP, SCROLL UP/DOWN
59 (U.S.A) to 61
N-key rollover
Concave, step sculpture
1, 1-1/2, 2
Typing and Erasing
Automatic Page Break
Keyboard I and
II
Shift Lock
Erase
Forward
Erase Backward
Editing
Decimal
Tab
Centering. margins, tabs
Automatic Reformatting
Block Move
Block Copy
Block Erase
Document Lock
Indent
FORTH
100, 120, 230V 50/6OHz
10°C to 35°C (50°F to 95°F)
20% to 80%
In millimeters: 342(W)X 264(H)X 510(0)
In inches: 13.S(W)X 1O.4(H) X 20. l(D)
9.2 Kg (20.3 1bs)
I
1-1

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0008 of 0187
1-2. Overview
Keyboard Unit
SW2
Self Diagnosis
1·2
CENTRO
Connector
CRT/Power Supply Unit
11110118801
UIIIIIUDI
~HIIIIU~I
IIIUIIIIUI
RS-232C
Connector
[
:;~=;!;~~ 1
MODEM
Fig. 1-1
* CRT Unit includes the Power
Supply Unit.
J.LFDD Unit
CPU PCB Unit
Line Jack
Phone
Jack

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0009 of 0187
CUT SHEET
'·3 System Overview PRINTER FEEDER
• IIF UNIT
MAIN UNIT
LINE
:s:
~
~ ~
--1'11
~!I
" :---.-...."
Cat
CENTRO CONNECTOR
PRINTER
Or
-0
o
EJ
.--"I!
rif---------+----i.. '. ,"iI
-iJf"
t I I Al'7oH t -
~ AP66 I
Cut IXO
VP3102
AP550n
AP500n
AP400n
o 01 ~t I
0-
APlOO/150
r - - - - , II EXTERNAL MODEM II ... 't1I--<rr-tr-t.~~--..J
J EXTERNAL I .I-~ ____________________ ~J
r I MODEM I -
--
11.---r..J
I I
I I
: [Q [Q] MODULAR PHONE JACK
! ~ rB1 MODULAR LINE JACK
:
PHONE I INote, Only models for USA and Japan
I have modular jacks. Since other
Oll----~
models do not have an internal
modem, they do not have these
jacks.
I ~~
LOP
-0 '
."w.
r tJ ::::::: : I ~
-
~"~
'-
~
Ll AP-IF03 I ~
AP-IF43 -G
A,"OO 0-
Fig, 1-2
1-3

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0010 of 0187
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O£JI

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0011 of 0187
'-5. Block Diagram Description
Block
CPU/ROM/
RAM
LSI Name Function
CPU MC6S000 16 bit microprocessor
CPU Clock: 5 MHz
System ROM
SV-ROM
Address bus: A I - A23 (A
19 and A20 not used)
Data bus: DO - DIS
The CPU controls the entire system. It responds to the
following two interrupts:
l. NMI: CPU operation is monitored by gate array #2. If
the CPU operates abnormally, gate array #2
resets the entire system.
2. IPLO: Inputs IRQ from DUART. (For more informa-
tion, see the
DUART item.)
If a key input is not received within a certain time, the CPU
saves the contents of the system RAM to disk and turns off
the screen. (When a key
is pressed, the screen is turned on
and text
is displayed.)
The contents
of the system ROM (256 KBYTES) are shown
below.
1. System Program
2. Self Diagnosis Program
3. Keyboard code table/CG
The SV-ROM is provided for the spelling check. When the
spelling check
is performed, it functions as a dictionary. (The
SV-ROM
is not available for some countries.)
The names of the dictionaries used and the availability of
the SV-ROM is shown below.
I. ROM 0: Yes
PARTS NO. IC6 IC7
NH7-06S4 0 -
NH7-0724 0 -
NH7-0S13 0 -
NH7-0S14 -0
NH7-1019 0 -
NH7-1020 -0
NH7-1021 - -
2. Dictionary name
DICTIONARY
American Heritage
American Heritage (British)
Librairie Larousse
Langenscheidt
IC8
-
-
-
-
-
-0
COUNTRY
USA, JAPAN
U.K., OCEANIA
QUEBEC, FRANCE
W. GERMANY
COUNTRY
USA, JAPAN
U.K., OCEANIA
QUEBEC, FRANCE
W. GERMANY
1-5
I

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0012 of 0187
1-5. Block Diagram Description
Block
CPU/ROM/
RAM
LSI Name
SV-RAM
Memory
Protect
Circuit
Gate Array # 1& System &
#2!RAM Video RAM
Function
The SV-RAM
(8 KBytes) is used to store a personal
dictionary
and the setup screen information. This personal
dictionary
and setup screen information are backed-up by
a lithium battery.
Personal dictionary: Dictionary registered by the user.
It is
used in the spelling check.
Setup screen: Includes the setup
data for the printer,
modem,
and other devices.
This circuit protects the contents
of the SV -RAM when the
power
is turned on and ofT and when the + 5V supply is
unstable.
The system & video
RAM consists of eight 4-bit D-RAMs.
(256 KBytes standard)
An optional RAM (128 KBytes) can
be added. These
RAMs are for video and system use.
1. Video RAM: Stores the CG-pattern for CRT display.
2. System RAM: Used to store the user Text, or for system
operation.
Gate Array # 1 Gate Array # 1 has the following functions:
1-6
1. CPU clock generator
Divides a clock signal
of approximately 20 MHz by four
and outputs a 5
MHz CPU clock signal.
2. CRT sync signal generation
HSYNC and VSYNC output.
3. Memory control signal generation __ __
Outputs the memory address, RAS, CAS, and WE signals
and controls the system & video RAM. Also shows if the
data output from ~mory is video data or CPU data.
Outputs the
CS V /C signal to Gate Array #2.
I

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
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1-5. Block Diagram Description
Block LSI Name Function
Gate Array # I & Gate Array
#2
Gate Array #2 has the following functions:
#2/RAM
1.
Decoder
Outputs the
I/O LSI and memory IC decode signals.
2. Video signal--.Seneration
The CS V
IC signal mUltiplexes the read data from
memory with the
CPU data and video data. The video
data
is then converted by the LDPS signal from parallel
to serial data and output to the
CRT unit.
3. Relay control signal
The relays at the
NCU are controlled as follows:
CD After a telephone ring is detected, the telephone line
is connected to the main unit circuit by the OFF
HOOK signal. (The line and telephone are still
connected.)
® Next, the telephone and telephone line are disconnect-
ed by the Phone signal. (Only the telephone line
is
connected.)
4. Reset signal delay control
RESIN signal is output after a delay of 0.7 ms.
CENTRO & Gate Array # 3 Gate Array # 3 has the following functions:
RS-232C
1. CENTRONICS printer interface
2. Keyboard interface
(1) The
CPU stores key data by scanning the keyboard
at 6.5 ms intervals.
The
DUART produces the key scan interval time.
(2) CC: Check code strobe
After the power switch
is turned on, the signal level
is lowered and the status of bit D7 is checked. If it
is on, self diagnosis is performed.
3.
Low Battery Detector
The Reset IC monitors the lithium battery, and when low
BAT = high, a battery mark
is displayed on the ruler
line.
4. FDD Controller
(1) Outputs the signal which drives the
FDD and reads
the
FDD status.
(2) Separates the read
data from the FDD into clock bits
and
data bits.
Note:
The
CPU controls data transfer between the FDD
and system RAM.
At this time, the CPU inhibits all interruptions.
1-7
I

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0014 of 0187
1-5. Block Diagram Description
Block
CENTRO &
RS-232C
Modem &
NCU
1-8
LSI Name
DUART
Modem
Chip
Modem
Filter
DTMF Tone
Generator
Function
The
DUART has the following functions:
1. The DUART has two ports. One port is for the internal
modem and the
other port is for the external modem or
printer. (External modem or printer is selected by setup
screen.)
2. Buzzer control
3. The DUART outputs IRQ to the CPU under the
following two conditions:
CD When the CPU key-scan timing signal is generated
by the internal counter
of Gate Array #2. TOBF is
output to DUART every 6.S ms. and DUART
outputs IRQ to the CPU.
@) When a telephone ring is automatically detected by
the main unit...
This
IC is a single chip modem which complies with Bell
212A and
CCITT V.22 standards. It has a 1200bps PSK
modem and fall back mode 300bps FSL modem functions.
The filter specifications conform to the Bell 212A and
CCITT V.22 standards.
This LSI outputs a dial tone to the telephone line without
the use
of a telephone set when automatic dialing is
performed.
These LSls and circuits are installed
in models with internal modems. Only
the U.S.A, ASIA, QUEBEC,
OCEANIA, and JAPAN have modem models
with internal specifications.
External modem specifications apply to other countries.
I

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0015 of 0187
"'T'l
qQ.
I
~
I--
CD
SW2
CENTRONICS I [;:===G n CN'
PRINTER
RS-232C
PRINTER/
EXTERNAL
MODEM
G=J
'---
D
SWl
l
,.....--
CNS
L--
f.LFDD I
CRT/POWER
UNIT
SUPPLY UNIT
11
~
--~
CN4
CNl
CNJD
Switch for
Self Diagnosis
Switches RS-line on the
CPU PCB to
"Host" or "Terminal".
KEYBOARD
UNIT
CPU PCB UNIT
IPHONE IC J DCN7 ~________ BATTERY
... ere are a so
" Th
I', Battery for [OJ
CN6
-- . . h ' SV-RAM
.-::__ umts Wit out ,
fLiNEI C ~ D ~ CN7 and CN6. ! Back-Up
L--..J \, ________ ,1
.....
a,
(")
o
:1
:1
CD
(")
....
o
~
r-
Q)
<
o
c::
....

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0016 of 0187
. Page
.2·4: Address Map ....... ~ ....; .. ~ ........ ~ .... ,...... 2~t
2-2; Initial-Flowchart ...............:................ 2-2
. . .... . Page~
2 3 c
,," "0 • n~ .. u.f·· .' . 2..1"
-." hClJit '~l]ptiOn ····•·.. ·f···· .. ··., .... ···;.. -.:

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0017 of 0187
2. THEORY
2-1. Memory Map
Address
®--
• AOOOOO
• FFFFFF
-- VPA
-- NOT USED
• 880000
__ GATE ARRAY 'Z
IJPOe50I ZCW-I 9 I
•
EOOOOO
• 810000
-- DTACK
• 860000
• 850000
• COOOOO
• 840000
-- NOT USED
• 830000
__ MODEM CHIP
S35Z13
• 8Z0000
__ DUART
MC8868 I
•
AOOOOO
• 810000 __ GATE ARRAY '3
IJPOe50 IZCW-I" I
®-- •
800000
©-- •
480000
ICI"~ICI7
-@
-- NOT USED
• 800000
IIZ8KBI
-- GATE ARRAY 'I
• "80000
IJPOe50I XW-Z18
-- OPTIONAL
ICI8~ICZI
(For CRT con'troll
RAM (I Z8KBI
•
""0000
--
SYSTEM & ICZZ-ICZ3
VIDEO RAM
• "ZOOOO
IZ58KBI
ICZ8~ICZ9
• 800000
-- NOT USED
@-+
• 400000
• "80000
-©
-- SYSTEM &
VIDEO RAM
®--
• Z80000
151 ZKBI
-- SVCSI
•
"00000
-@
IC8
-- NOT USED
• Z80000
-®
• Z40000
-- SV-ROM
-- SVCSO
IC1.ICO
• zooooo
-®
-- NOT USED
CD--
• ZOOOOO
• O"ZOOO
-- SV-RAM I8KBI
• 040000
-- SYSTEM ROMIZ58t<Bl
• 00000o
2-1

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
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2-2. Initial Flowchart
1. Flowchart
CD
0
®
0
G)
@
(j)
G)
G)
@)
(0
@
2-2
self-diagnosis
routine

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0019 of 0187
2-2. Initial Flowchart
2. Flowchart Description
CD There are SI2K bytes of space allocated for the System & Video RAM. However, this machine
only uses a maximum
of 384K bytes for the System & Video RAM. An R/W check is done
for every
128 K bytes of this area, and the RAM size is checked.
(Only addresses $ 400000, $ 420000, $ 440000, and $ 460000 are checked.)
® Gate Array # I has a register for control of the CRT. Initialize the screen size, H and V SYNC
signals, and screen
ofT registers.
CD DUART has two kinds of registers for control of two RS-port.
Initializes these registers.
8) • Gate Array # 3 has one register for control of the drive R/W and one keyboard key strobe
register.
Initializes these registers.
• Gate Array #2 has registers for control of the timer, video signals and etc.
Turns ofT Output Enable for the Video signal and turns ofT the OfT Hook signal.
® The modem chip operates on the basis of 29 commands. Sets the phase synchronization for the
internal
PLL circuit and set the pin state of modem chip. (The TxD and RxD pins are high
impedance.)
® Disables the CS signal for DTMF tone.
o Reads the test switch status. If D7 is low, jump to the self-diagnosis routine.
® Initializes the system & Video RAM.
® Starts the key scan.
@ Reads the country code.
QJl Enters the FORTH execution mode. FORTH performs initialization.
@ Setup screen information and the user dictionary are stored in SV-RAM. A sum check is
performed for the setup screen information. If the values are unequal, the default value is set
according to the country code.
The user dictionary is checked in the same way.
If an error is detected, the dictionary is cleared.
@ Displays the editing screen.
2-3
I

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Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
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2-3. Circuit Description
1. CPU PCB Unit
(1) Operation Outline
Operation
of CPU and peripheral equipment after initialization is shown below. (Refer to the
block diagram description for
an outline of each element)
CD When a key is input.
CPU gets and processes keydata at intervals of 6.5 ms.
CD-I. The Gate Array # 2 has a timer to count the key strobe interval time.
2-4
CD-2. The KTOBF signal is outputted to the DUART when the count is full count. (The
KTOBF: 6.5 ms period)
CD-3. Upon detection of the KTOBF signal, the DUART outputs IRQ signal (6.5 ms period)
to the CPU.
CD-4. After receiving the IRQ, the CPU outputs keystrobe data to Gate Array # 3 to get
key codes from the keyboard.
CD-S. CPU arranges the codes with a keytable according to the country code and convert
them into the system code (like ASCII code).
CD-6. CPU stores the codes into the text area in the SYS & video RAM, reads their
character-pattern from the
CG area in SYS ROM, and saves it into the video area
into the SYS & video RAM.
CD-7. Read and write timing for these data are controlled by Gate Array # I.
CD-8. Gate Array #2 reads the video data and converts it from parallel to serial with the
LDPS signal
and outputs the video data to the CRT.
o When you set the setup screen.
The
CPU stores two kinds of information in SV-RAM.
~ I. Setup information
l2. Personal dictionary
Whenever write the data, the
CPU checks PF AIL bit. If PF AIL bit is on, the CPU stops
to write the SV-RAM's data.
If it is off, the CPU writes it into the SV-RAM. (PFAIL bit
is set when the + 5V is instable.)
® Text save
FOC is built in the Gate Array #3. Read/Write of JLFDD is controlled by this LSI. When
saving Text on the disk, the
CPU saves system RAM data (includes text) and SV-RAM
data on the disk. The
data is saved separately in the disk text area and SV-RAM area.
o Text call
0-1. Text data and SV-RAM data are loaded together if user set load setup or spelling
from the disk at the setup screen when loading Text
data from disk to System RAM.
0-2. The read data signal from the J.LFDD is separated into its components signals, clock
bit and
data by Gate Array # 3.
® When you leave from keyboard:
If the screen blanking time is not set to "Never" in thesetup screen, text data is automatically
saved to disk
by stopping key input for the established time.
If CPU doesn't get key data for three consecutive scans, the screen-off count begins from
this point.
If any key input is indicated before count end, the counter is cleared.
If count is full count, the CPU inhibits all interruptions and text data is transferred to FDD.
Then the video signal goes high and the picture is turned off (The system and video RAM
information remains as is. In this state, the Video signal does not function but other signals
continue to operate.)
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“RaskinDoc062_2-05.PICT” 144 KB 2000-02-25 dpi: 400h x 400v pix: 1880h x 2968v
Jef Raskin Document # 062 -- Canon Cat Computer Repair Manual
Source: David T. Craig Page 0021 of 0187
2-3. Circuit Description
@ For communications (The example is for Automatic answering.)
@-l. The telephone set is connected with an exchange through CN7 and CN6 during standby.
In this case, DC-48V voltage
is applied between 3 and 4 pin of CN 6.
@-2. The calling indicator signal is input to the telephone set from the exchange. The signal
also makes the telephone set ring.
(Calling indicator
signal: 16 Hz, 75 V ring tone signal)
@-3.
DC element is removed from the calling indicator signal by C57, and only the AC signal
is applied to PC I.
The signal then appears on the RG-line.
@-4.
The RG signal is connected to DUART pin 2.
The level is periodically checked by the CPU. If there are variations in the signal level,
the
CPU counts the number of low levels (the number of rings).
When this value becomes equal to the number
of rings, auto answering is done.
@-5.
Turn on the OFF-Hook signal and switch relay K2 to the NCU side. (For auto answering,
leave relay K 1 as
is.
For manual answering, turn on the phone signal and disconnect the telephone set line
from the mainframe circuit.)
@-6. A DC-current loop
is then established between the exchange and TI (1-2).
@-7. The
DC element is removed by TI and the carrier is transferred between 4 and 3. It
is then converted by R38 and input to Filter IC38.
@-8. IC38 has two
Op Amps. One is for the sending carrier, and one is for the receiving carrier.
This Ie splits the receiving carrier from the sending carrier, amplifies it,
and inputs it
to RxIN.
@-9. IC 38 also has two filters.
The modem chip sets the answer mode for these filters. (The
low filter
is used for receiving; the high filter is used for sending.)
The carrier is output from RxOUT via the low filter.
@-IO. The modem chip judges whether the carrier
is FSK or PSK. The CPU reads the modem
chip status to obtain the result
of this judgement.
@-Il. The carrier is then demodulated by the modem, and the serial data is output to DUART.
@-12. DUART converts the serial data from serial to parallel.
The data is then stored in the system & Video RAM.
2-5
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