Radio Shack TRS-80 Model 100 User manual

.
MODEL I OO
PORTABLE COMPUTER
Catalog Numbers 26-3801/3802
CUSTOM MANUFACTURED FOR RADIO SHACK H A DIVISION OF TANDY CORPORATION
Radio /hack
Service Mmm iD
26
-
3801/3802

TABLE OF CONTENTS
PAGE
NUMBER
I. INTRODUCTION
GENERAL.
SPECIFICATIONS.
CONNECTORS, SWITCHS AND CONTRAST VR
II. disassembly/reassembly
DISASSEMBLY.
REASSEMBLY .
Ill PREVENTIVE MAINTENANCE
ADJUSTMENT OF THE TRS-80 Model 100.
CLEANING OF THE DOBY AND LCD DISPLAY-
MODEM TRANSMITTING LEVEL ADJUSTMENT . ..
IV. THEORY OF OPERATION
GENERAL.
CPU (MSM80C85ARS) .
MEMORY .
ADDRESS DECODING AND BANK SELECTION .. .
MEMORY MAP.
I/O MAP AND I/O PORT DESCRIPTION.
KEYBOARD .
CASSETTE INTERFACE CIRCUIT .
PRINTER INTERFACE CIRCUIT.
BARCODE READER INTERFACE CIRCUIT.
BUZZER CONTROL CIRCUIT.
SYSTEM BUS .
LCD INTERFACE CIRCUIT.
CLOCK CONTROL CIRCUIT.
SERIAL INTERFACE CIRCUIT.
LIQUID CRYSTAL DISPLAY.
POWER SUPPLY AND AUTO POWER OFF CIRCUIT
RESET CIRCUIT.
V. TROUBLE SHOOTING
HOW TO MAKE USE OF THIS SECTION.
TROUBLE SHOOTING GUIDE.
CHECK LIST.
VI. EXPLODED VIEW AND PARTS LIST
EXPLODED VIEW.
PARTS LIST .
VII. DIAGRAMS
SCHEMATIC DIAGRAM.
P.C.B. VIEW.
1- 3
1- 4
1 - 6
2 - 1
2 - 2
3- 1
3- 1
3- 1
4- 1
4- 2
4- 2
4- 3
4- 6
4- 7
4- 8
4- 9
4-10
4-11
4-11
4-12
4-13
4-15
4-17
4-26
.4-32
.4-34
5- 1
5- 2
5-12
6 - 1
6- 3
7- 1
7- 3

appendix a/ installation OF OPTIONAL RAMs AND ROM
appendix b/character code table .
APPENDIX C/ LSI DESCRIPTION
MSM80C85ARS (CPU)
MSM81C55RS (PIO) . C ' 1
IM6402 (UART) C11
MPD1990AC (TIMER) ... . 015
MC14412 (MODEM) .. C-19
TC5518BF-25 (RAM) ... C ' 24
LH-535618 (ROM) C-28
. C-31

FIGURE
NUMBER
DESCRIPTION
PAGE
NUMBER
1-1
1-2
2-1
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
4-18
4-19
4-20
4-21
4-22
4-23
4-24
4-25
4-26
4-27
4-28
4-29
4-30
4-31
4-32
4-33
4-34
4-35
4-36
4-37
4-38
6-1
6-2
7-1
7-2
7-3
7-4
7-5
7-6
Front View.
Keyboard Layout.
Disassembly Procedure.
System Block Diagram.
Internal Wiring Diagram of RAM Pack
Address Decoding for RAM Chip.
Standard and Optional ROM Selection ....
Memory Map.
I/O Address Decoder.
Condition of Pressing “T" Key.
Modulation Circuit of Cassette Interface ..
Demodulation Circuit of Cassette Interface
Remote Circuit of Cassette Interface.
Printer Interface Circuit.
Bar Code Reader Interface Circuit.
Buzzer Control Circuit.
LCD Interface Circuit.
LCD Interface Timing Chart.
Data Input Condition of mPD1990AC ....
Time Set Condition of /uPD1990AC.
Time Read Condition of /iPD1990AC.
Data Output Condition of /iPD1990AC
Control Register Load Condition of IM6402
Status Read Condition of IM6402 .
Data Transmission Condition of IM6402 . ..
Data Reception Condition of IM6402 .
MODEM/RS-232C Exchange Circuit.
RS-232C Interface Circuit.
MODEM LSI and Peripheral Circuit.
Transmission Filter Circuit.
Reception Filter and Comparator Circuit ...
MODEM Connector Interface Circuit.
Construction of LCD Panel .
Operation Theory of LCD Panel.
LCD Electrodes.
LCD View Angle .
HD44103 Internal Block Diagram.
HD44102 Internal Logic Diagram .
LCD Waveform.
Power Supply and Reset Circuit.
Oscillation Waveform.
Exploded View.
Bottom View.
MAIN P.C.B.-Schematic Diagram.
LCD P.C.B.-Schematic Diagram.
MAIN P.C.B.
MAINP.C.B.
LCD P.C.B. . . . . ! . ! .
LCD P.C.B.
. 1 - 1
. 1 - 2
. 2- 1
.4- 1
.4- 3
.4- 4
.4- 5
. 4- 6
. 4- 7
. 4- 8
. 4- 9
.4- 9
. 4-10
. 4-10
.4-11
. 4-12
.4-13
. 4-14
.4-15
.4-16
. 4-16
.4-17
.4-18
.4-19
. 4-19
. 4-20
.4-21
.4-22
.4-23
, 4-24
4-24
4-25
4-26
4-27
4-28
4-28
4-29
4-30
4-31
4-33
4-33
6- 1
6 - 2
7- 1
7- 2
7- 3
7- 4
7- 5
7- 5

. A- 1
A-1
C-1
C 9
80C85 Functional Block Diagram.
. C- 1
. C- 1
U‘4
. C- 6
. C- 8
0-4
. C- 8
0-0
n a
. C-9
r 7
. C-10
. C-10
O-o
C-9
81C55 Pin Configuration and Block Diagram ...
. C-11
. C-13
O-1 u
. C-14
o -1 i
. C-14
O-1 z
C-13
81C55 Timer Output Waveform Countdown from 5 to 1 .
. C-15
. C-15
O- 14
. C-16
0-1 O
. C-20
O* ID
. C-21
O- 1 /
C-18
C-19
A/PD1990AC Command Input Timing Diagram.
/iPDI 990AC Data Input/Output Timing Diagram.
. C-22
. C-23
. C-26
O-ZU
. C-26
. C-26
. C-27
w"Zo
TPRR1 RRF-9R Pin 1 avnut ..
. C-28
r ok
. C-29
U“Z J
. C-29
u'Zu
. C-30
o-z /
. C-31
. C-32
C-30
LH-53518 Timing Diagram.
. C-32
TABLE
NUMBER
DESCRIPTION
PAGE
NUMBER
I/O Man .
.4- 7
.4-8
4-Z
.4-12
.4-13
4-4
.4-21
4-0
.4-22
4-D
C-1
80C85 Interrupt Priority, Restart Address and Sensitivity .
. C- 5
. C-7
u-z
.. C-7
U-o
. C- 8
0-4
. C-15
v‘0
. C-28
0-0
C-7
LH-535618 Pin Assignment.
. C-31

SECTION I
INTRODUCTION

FRONT VIEW
1-1

INTRODUCTION
GENERAL
This manual is prepared for the TRS-80 Model 100 technicians working in field or in repair centers.
The user of this manual should be acquainted with Z-80 and 80C85 (8085) microprocessors and also with
81C55 PIO and IM6402 UART LSIs.
Detailed technical information for those microprocessors and LSIs is provided in APPENDIX C of this
manual.
This manual consists of seven sections and three appendices:
• Section I
This section gives general information on the TRS-80 Model 100 such as specifications, switch functions
connectors and special features.
• Section 11
This section describes the disassembly and reassembly procedures.
• Section III
This section describes preventive maintenance and adjustment of the TRS-80 Model 100.
• Section IV
This section describes general theory of the TRS-80 Model 100 operation, including operational theory
of main P.C. Board assembly, LCD Board assembly and keyboard assembly.
• Section V
This section describes how to troubleshoot the TRS-80 Model 100.
• Section VI
This section provides a part list and an exploded view of the TRS-80 Model 100.
• Section VII
This section provides schematics, P.C. Board diagrams and silk screen views of P.C. Boards of the TRS-80
Model 100.
• Appendix A provides instructions for installing the optional ROM and additional RAMs.
• Appendix B provides character code chart of the Model 100.
• Appendix C provides technical information of microprocessors and UART LSIs.
The Model 100, a portable computer that fits easily into a regular sized briefcase, has many special features
and functions for home and business use.
Its five built-in Application Programs offer various uses:
• BASIC
BASIC lets you write and run your own programs.
Also, BASIC provides various mathematic functions (as described in PART-1 II of owner's manual).
• TEXT
TEXT Lets you create new files containing memos, documents or text of any kind.
• ADDRSS
ADDRSS lets you get information such as addresses and telephone numbers from the ADRS file.
• SCHEDL
SCHEDL lets you get information concerning appointments, meetings, etc., from the NOTE file.
• TELCOM
TELCOM lets you use the TRS-80 Model 100 as an auto-dialer or for computer-to-computer communi¬
cations.
1-3

In addition to Application Programs, you can connect the following peripherals to the Model 100:
• Cassette recorder to store programs or data on cassette tape.
• Printer to print copies of documents, programs or data.
• Bar code reader to identify the product marking codes of various marchandises. (Optional/extra soft¬
ware required.)
• Communication interface to transfer/receive data to/from the Model 100 and another computer (Acous¬
tic Coupler or Modem Cable required).
SPECIFICATIONS
(1) Main Components
(a) Keyboard
71 keys (9x8 matrix)
• Alphabet keys .
• Number keys.
• Picture-control keys .
• Function keys .
• Special symbol keys .
• Mode keys ....
• Other special-use keys
(b) LCD display
• Display panel.
27
10
7
8
8
5
6
240 x 64 Full-dot matrix
(c)
(d)
(e)
1/32 Duty
1/6.66 Bias
• Dot pitch.0.8 x 0.8 mm
• Dot size . 0.73 x 0.73 mm
• Effective display area.191.2x50.4 mm
Operation batteries
• Batteries.... Four type AA Alkaline-manganese batteries
• Operation time. Five days (At four hours/day)
Twenty days (At one hour/day)
(Note: With I/O disconnected)
Memory protection battery (On main P.C.B.)
• Battery. Rechargeable battery
• Protection time .About 40 days (8 KB)
About 10 days (32 KB)
• Recharge method.Trickle charge by AC adapter or operation batteries
LSIs
• CPU.80C85
Code and pin compatible with 8085
• ROM .Maximum 64 KB (2 Banks of 32 KB)
Standard 32 KB
Option 32 KB
1-4

• RAM .Maximum 32 KB
Standard 8 KB RAM PACK
Incremental 8 KB RAM pack on P.C.B.
• Clock/Calender./iPD1990AC
No leap year/No February 29
(f) Dimensions.11-4/5"(L) x 8-4/9"(D) x 2"(H)
(g) Weight .3 lbs. 13.5oz.
(2) I/O Interface
(a) R S-232C
Conforms to El A Standard
Signal.
TXR (Transmit Data)
RXR (Receive Data)
RTS (Request to Send)
CTS (Clear to Send)
DSR (Data Set Ready)
DTR (Data Terminal Ready)
Communications Protocol
• Word length.6, 7 or 8 bits
• Parity.NON, EVEN or ODD
• Stop Bit Length.1 or 2 bits
. Baud Rate . 75, 110, 300, 600, 1200, 2400, 4800, 9600,
19200 BPS
• Maximum Transmission Distance .... 5 meters
• Driver maximum voltage output.±5 volts
• Driver minimum voltage output.±3.5 volts
• Receiver maximum voltage input .... ±18 volts
• Receiver minimum voltage input .... ±3 volts
(b) M odem/Coupler
Conforms to BE LI 03 Standards
• Baud Rate . 300 BPS
• Programmable Items
* Data length.6, 7 or 8 bits
* Parity.NON, EVEN or ODD
* Stop bit .1 or 2 bits
• Full Duplex .Answer mode/Originate mode, Switchable
• Other functions.Hang-up function
Auto dialer function
(c) Audio cassette interface
• Data Rate. 1500 BPS
(MARK: 2400 Hz, SPACE: 1200 Hz)
(d) Printer interface
Conforms to Centronics Interface Standards
• Handshake Signal.STROBE, BUSY, BUSY
1-5

(3) Special functions
Automatic power OFF
When there is no program operation (awaiting command) for ten minutes, the power is automatical¬
ly cut off.
To start again, the power switch must be switched OFF and then ON, thus releasing the automatic
power OFF condition. (The display will be the same as before the power was cut off)
CONNECTORS, SWITCHES AND CONTRAST VR
(1) Connectors
RS-232C.25 pins (DB-25S)
Printer.26 pins (FRC2-C26-L13-ON)
Modem. 8 pins (TCS-4490)
Cassette. 8 pins (TCS-4480)
Bar Code Reader . 9 pins (A-7224)
System Bus.40 pins (1C socket)
AC Adapter.5.5 mm diameter (center-minus)
(2) Switches
(a) P OWER Switch
Move this switch towards the front to turn the power ON. To conserve the batteries, the
Model 100 automatically turns the power off if you do not use it for 10 minutes.
When an automatic power-off occurs, the switch will still be in the ON position even though
the power is OFF.
To turn the power ON, move the switch to the OFF position, then back ON.
(b) A NS/ORIG Selector
If you are originating a phone call to another computer, set this switch to ORIG.
If another computer is calling your Model 100, set to ANS.
ANS ORIG
(c) D IR/ACP Selector
This selector allows you to select either direct or acoustic coupler connection.
If you are communicating with another computer over the phone lines via the built-in Direct
Connect Modem, set this switch to DIR position. If you are using the optional/extra Model 100
Acoustic Coupler (26-3805), set this selector to ACP position.
DIR ACP
1-6

(d) M EMORY POWER Switch
This switch is for preventing discharge of the Ni-Cad battery for RAM back-up.
The Model 100 will not operate regardless of the setting of the power switch unless this switch
is ON.
Set this switch to OFF position if the Model 100 is not to be used for a long time.
Note that the RAM will not be backed up when this switch is set to the OFF position.
ON
OFF
(e) RESET Switch
If the Model 100 "lock-up" (ie., the display will "freeze" and all keys seem to be inoperative),
press this button to return to the Main Menu (start-up) screen. It's highly unlikely that the
Model 100 will lock-up when you are using the built-in Application Programs.
However, this situation may occur with customized programs.
(f) DISPLAY ADJUSTMENT DIAL
This control is for adjusting the contrast of the LCD display relative to the viewing angle.
1-7

SECTION II
DISASSEMBLY/REASSEMBLY

DISASSEMBLY / REASSEMBLY
DISASSEMBLY
CASE:
(1) Disconnect the cables from the unit.
Taking care not to scratch any key top, turn the unit over and remove the four screws ® from the
upper and lower cases.
(2) Remove the upper case; it opens to the right side.
Note that the upper and lower cases are secured by snaps.
Also, do not apply too much force when pulling open; the LCD and keyboard connectors are attached.
(3) Remove the LCD and key board connectors from the main P.C.B.
(4) Remove the buzzer connector from LCD P.C.B.
K/B P.C.B.:
(1) Remove the five screws © and then remove the K/B P.C.B. and K/B supports.
LCD P.C.B.:
(1) Remove the four screws © and then remove the LCD P.C.B.
MAIN P.C.B.:
(1) Remove the seven screws ©.
* (2) Remove the MAIN P.C.B. upward, taking care when removing the RESET switch and battery contact
spring.

REASSEMBLY
MAIN P.C.B.:
(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.:
(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.:
(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:
(1) Position the upper case to the risght side of the lower case, taking care not to scratch the key top.
(2) Attach the LCD and K/B connectors to the MAIN P.C.B.
(3) Place the upper case over the lower case, taking care that the cable is not pulled out of place.
(4) Align the upper and lower cases so that the tabs fit well.
(5) Turn the cases over, and secure them together by using the four M3 x 8 screws.
2-2

SECTION III
PREVENTIVE MAINTENANCE

PREVENTIVE MAINTENANCE
ADJUSTMENT OF THE TRS-80 Model 100
The TRS-80 Model 100 is completely aligned and adjusted at the factory during production. Therefore
no electrical adjustments will be required.
CLEANING OF THE BODY AND LCD DISPLAY
(1) To avoid operational trouble, keep the TRS-80 Model 100 clean always.
(2) To clean the body and LCD, use soft, dry, lint-free cloth.
(3) For tough stains, clean the body or LCD using benzol.
Do not use any other solvents except for benzol.
MODEM TRANSMITTING LEVEL ADJUSTMENT
(1) Set the DIR/ACP switch to DIR position.
(2) Connect a 600 Ohm dummy Load between Pin-1 (RXMD) and Pin-7 (TXMD) of the MODEM CON¬
NECTOR (CN4).
(3) Connect a AC Voltmeter between RXMD and TXMD.
(4) Set the TRS-80 MODEL 100 in BASIC mode and enter following commands to generate carrier.
OUT 178, 47 (ENTER)
OUT 168, 02 (ENTER)
(5) Adjust VR2 so as to read —14 to —17 dBm on the AC Voltmeter both for ANS/ORIG modes.
3-1

SECTION IV
THEORY OF OPERATION

Fig. 4-1 System Block Diagram
GENERAL
The TRS-80 Model 100 has three principal LSIs:
• 80C85 CPU
This is the Central Processing Unit which control all functions.
• 81C55PIO
This is the Parallel Input/Output interface controller which controls the parallel printer, key board,
buzzer, clock and LCD.
• IM6402 UART
This is the Universal Asyncronous Receiver Transmitter which controls the serial interface (RS-232C
or MODEM).
The Input/Output for a cassette recorder and the Input of the BCR are controlled by CPU directly through
its SOD, SID and RST 5.5 terminals.
ROM and RAMs are connected to the system bus. ROM is available only for alternative selection of Stan¬
dard or Optional.
NOTE: On the figure in this section, the solid line shows high-level active line and the broken line shows
low-level active line.
4-1