Epson PX-8 User manual

EPSON
.--
TECHNICAL MANUAL
PX-B
H8490021-1

INTRODUCTION
The EPSON PX-8 is a general-purpose portable computer driven by an incorporated rechar-
geable battery. Standard features include a
micro cassette drive, ROM capsule and RS-232C
interface allowing the machine to independently handle a variety of applications. The system
can also be expanded by connecting peripheral equipment such as a printer. Long time
steady operation has been realized by employing the battery-powered supply system with its
large capacity of 1100 mAH. A recharge control circuit to protect the battery from over-
charge and an auxiliary
battery (90 mAH) for backup have been added to enhance reliability.
MICROCASSETTETM is a trade mark of OLYMPUS OPTICAL Co., Ltd.

TABLE OF CONTENTS
CHAPTER 1 GENERAL DESCRIPTION
CHAPTER 2 PRINCIPLES OF OPERATIONS
CHAPTER 3 OPTION (PRINCIPLES OF OPERATIONS)
CHAPTER 4 DISASSEMBLY/ASSEMBLY
CHAPTER 5 TROUBLE SHOOTING
CHAPTER 6 MAINTENANCE
CHAPTER 7 APPENDIX
REV.-A

CHAPTER 1
GENERAL DESCRIPTION
REV.-A
1.1 Specifications............................................................................................................ 1-1
1.2 Name of Major Parts................................................................................................. 1-4
1.3 Major Parts................................................................................................................. 1-5
1.4 Interface..................................................................................................................... 1-8
1.5 Connection Cable (option) ........................................................................................ 1-15

REV.-A
1.1 Specifications
(1) Dimension:
(2)
Weight:
(3) Environment:
• Temperature
•
Humidity
(4) Power:
•
Consumption:
• Battery:
• AC adapter
output:
(5) Keyboard:
(6) LCD:
(7)
Microcassette TM:
(8) Interface
• RS-232C:
297 mm (width) x 216 mm (depth) x 4 7mm (height)
Approx. 2.3 kg
Operating
Recharging
Not operating
Storing data
(not operating)
Operating
Not operating
5
~ 35°C
5
~ 35°C
-20 ~ 60°C
(below 30°C
for a long period of time)
o ~ 40°C
10
~ 80% (non-condensing)
5 ~ 85% (non-condensing)
Approx. 325 mW (when micro cassette, speaker, ROM capsule,
RS-232C, SERIAL are
not operating)
Two Ni-cd rechargeable batteries
Main battery
Auxiliary battery
Voltage 4.8V 4.8V
Capacity 1100 mAH
90mAH
Charging current 330 mA MAX.
10 mA MAX.
Charging voltage
5.6 ~ 6.4V
5.7 ~ 6.0V
6.0V, 600 mA
72 keys (include 9 function keys)
3
mode indication lamps
480 (width) x 64 (height) dots (80 x 8 characters per screen)
1/64 duty, adjustable VIEW ANGLE
Tape speed
Drive
Track
Frequency characteristic
Data file
Connector
Voltage
Transmission speed
Mode
1 -1
2.4 cm/s
Center capstan
Two-truck, one-channel
315 ~ 4KHz
Sequential file with directory
8-pin mini-DIN connector
± 8V (ON/OFF control by software)
75 ~ 19200 BPS
Full duplex/half duplex

• SERIAL:
• Speaker:
•
Analog input:
• Bar code:
Connector
Voltage
Transmission speed
REV.-A
8-pin mini-DIN connector
± 8V (ON/OFF control by software)
150, 600,4800, 38.4K BPS
Audio response controlled by software or by micro cassette
(with adjustable volume)
Input voltage
A/D converter o
~ 2.0V
6-bit (Resolution: approx.0.03V)
Can connect to high-resolution (0.19mm) or low-resolution
(0.33mm).
(9)
CPU and memory
• Main CPU:
• Slave CPU:
• Auxiliary CPU:
• Main RAM:
• Video RAM:
• ROM:
• ROM capsule:
Z-80,2.45MHz
6303, 614kHz
7508, 200kHz (with battery backup)
64kB D-RAM (with battery backup)
6kB static RAM (with battery backup)
32kB
Two capsules can be incorporated.
(8
~ 32kB per capsule)
1.1.1 Available models
The following models are available for this computer. However, major differences among these
models are restricted
to keyboard and AC adaptor specifications, the internal hardware is the
same.
Table 1-1
Model Keyboard AC adaptor
H101AAA
ASCII (U.S.A.) HOOAAA: 1
20V 60 Hz
H101AAC ASCII HOOAAA: 1 20V 60 Hz, HOOAAU-B: 240V 50 Hz,
HOOAAU-A:
240V 50 Hz
H1 01 ABA HASCII (U.S.A.) HOOAAA: 120V 60 Hz
H101AUA England HOOAAU-A: 240V 50 Hz
H101AFA France HOOAAF: 220V 50 Hz
H101AGA
Germany HOOAAG:
220V 50 Hz
H101A SA Sweden HOOAAG: 220V 50 Hz
H101ADA Denmark HOOAAG: 220V 50 Hz
H101 ANA
Norway
HOOAAG: 220V 50 Hz
1-2

REV.-A
1.1.2 Specifications of option
Optional features are summarized in
the table below. They provide you with system expansion to
meet your specific demands or flexible system configuration by using universal option.
Table 1-2
Name Application/Descriotion
# 723 cable For
floppy disk drive (serial)
#724 cable For acoustic coupler (RS-232C)
#
725 cable For
printer (RS-232C)
#726 cable Null
modem (for interconnection between two EPSON PX-8
computers via RS-232C interfacing)
CX-20/21 Acoustic coupler
PF-10 3.5 inch
floppy disk drive
TF-15/TF-20 5.25 inch floppy disk drive
RAM DISK UNIT
Additional 120/60 kB RAM
UNIVERSAL UNIT A
through-hole circuit board and a case
MODEM UNIT Built-in
modem (for U.S.A. only)
MULTI UNIT RAM + MODEM (for U.S.A. only)
EPSON PRINTER Verious
models with RS-232C interface
1-3

REV.-A
1.2 Names of Major Parts
2
•
(Front view)
(Bottom view)
8
• 9
10
pi" •• ni
(Left side view) (Right side view)
(Rear side view)
Fig. 1-1
Table 1-3 Major Component
No. Name No. Name
1
VIEW ANGLE VOLUME (adjustable view 10 Power switch
angle due to temperature complement)
11 Speaker output (for external speaker)
2
Microcassette (program load/save and
sound generation)
12
Analog input interface (analog input/
joystick)
3 LCD panel
unit
13 Bar code reader interface
4 LCD panel open
switch
5 Keyboard unit
14
RS-232C interface (for connection to
acoustic coupler/printer, etc.)
6 Battery
cover (to replace main battery)
7 ROM
cartridge cover (for replacement of
ROM capsule, and INITIAL RESET)
8 Reset switch
15
High-speed serial interface (for connec-
tion to floppy disk drive)
16
Expansion interface (for connection to
optional unit/universal unit)
9 Speaker
volume (internal/external
speaker
volume adjustment)
1-4

REV.-A
1.3 Major parts
The main unit consists of five parts and a case as shown in Fig. 1-2.
CD MAPLE board
A
control board realizing compact size and low power consumption with CMOS, flat package
type multifunction gate arrays and various chips on it.
CD Micro cassette
Consists
of control board and driving mechanism. Reads and writes data from and to the tape.
Q) Keyboard
Has
72 keys on it (73 keys for Japanese use), 9 of which are function keys. Also has three in-
dicators which show the input mode.
CD LCD
Consists
of 480 (width) x 64 (height) dots, can display a total of 480 characters.
® Main battery
A rechargeable Ni-cd battery with a capacity of 1100 mAH. It supplies power necessary for
the normal circuit operation.
Bottom side
Fig. 1-2
1.3.1 MAPLEboard
Power consumption is considerably reduced by employing power-saving C-MOS. On-board inte-
gration has become easy by employing customized LSls and chips. Although both sides of the
boards are utilized, the back side mainly includes chips such as resistors and capacitors.
~-ROM capsule Internal speaker
Front
view Rear view
Fig. 1-3
1-5

REV.-A
External interfaces (shown in Table 1-4) and two ROM capsules on the board provide a system
configuration suitable for your needs or implementation of an application program. An auxiliary
rechargeable
battery of 90 mAH is also incorporated which supplies power in order to ensure
normal
circuit operation when the voltage of the main battery falls down below a certain value.
Table 1-4 External Interfaces
Item Function Note
RS-232C
11 0 ~ 19200 BPS, Operator-selectable:
transmission speed,
RS-232C level X-ON/OFF, etc.,
SERIAL
38400 BPS MAX., Operator-selectable:
transmission speed,
RS-232C level X-ON/OFF, etc.,
Barcode Read at TTL level Read program and bar code reader are required.
Analog input
Analog or joystick input Analog input line has +5V pull up function.
(with trigger)
External speaker o
~ 6Voutput
8.0
0.2W
1.3.2 Microcassette
The microcassette consists of a control board and drive mechanism. Operations such as FF,
REW, etc. are controlled by software, resulting in high reliability compared with manual control.
Increased chip
implimentation has permitted a reduction in size of the control board.
This cassette drive operates at a tape speed of 2.4 cm/s, and reads or writes data effectively utiliz-
ing a tape
counter and directory which contains file names, file starting addresses, etc.
Fig. 1-4
Mechanical components include a tape drive motor and its driving mechanism, R/W heads and
their mechanisms, reels, etc. The control board controls the revolving speed of motor, load/
unload of R/W heads and R/W operation.
To enable sound output, it provides signals to an internal or external speaker after amplifying them
twice. For reading data, duplicated amplification circuits eliminate high frequency component
(noise) and detect the peak of signal to ensure highly reliable sound output.
1-6

REV.-A
1.3.3 Keyboard
Matrix keyboard uses mechanical contact switches. Switches, reverse-current protection diode
and mode indication LED lamps are implemented on the control board.
Fig.
1-5
1.3.4 LCD
The LCD is a twist pneumatic (TNM) effect type liquid-crystal display. The screen angle can be
changed arbitrarily.
VIEW ANGLE volume is provided to correct the change of liquid crystal dis-
play condition caused by temperature rise or fall.
r
Fig. 1-6
1.3.5 Main battery
The main battery is Ni-Cd with a nominal voltage of 4.8V. When the battery is fully charged, the
voltage is 5.0V or more, enough to provide power for circuit operation. The battery can be easily
removed and replaced
by removing the battery cover on the bottom of the unit.
Fig.
1-7
1-7

REV.-A
1.4 Interface
As shown in Table 1-3, the unit has eleven connectors: among them, CN3, CN4 and CN5 have a
slide-lock mechanism.
Table 1-5 Interface Connectors
Name
Number
Function
of pins
CN1
3 AC adapter
connection interface
CN2 2 Main
battery connection interface
CN3
20
Incorporated microcassette interface
CN4
22 Keyboard interface
CN5
16 LCD interface
CN6 8 High speed serial interface
CN7 8 RS-232C interface
CN8
50 Expansion interface
CN9 3 Bar code reader interface
CN10
3 Analog input interface
CN11 2 External speaker interface
Note: CN5 is integrated on the back of MAPLE board.
Table 1-6 CN 1 (AC Adaptor) Pin Assignments
Pin No. Signal name
Definition
1 VCH Charging voltage
2 -Undefined
3 GND Ground
Table 1-7 CN2 (Battery Connection) Pin Assignments
Pin No. Signal Name Definition
1 VB Main battery voltage
2 GND Ground
1-8

REV.-A
19---------3 1
Table 1-8 CN3 (Incorporated Microcassette) Pin Assignments
E0CiiJj
20----------2
Pin No. Signal Name Definition
1 VLSW
Circuit voltage supply (through read gate)
2 VLR Circuit voltage supply (read amp. power supply)
3,4
GND Ground
5 RDSP Sound
output of read data
6
WE
7 RDMC Read signal
8
WD Write data
9
HMT
Head pinch motor control
10 CNTR Counter
11
MT B Capstan
motor drive control
12 MTA
Capstan motor drive control
13 HSW
Head switch status
14
MT C Capstan
motor speed control
15, 16 VBSW Battery voltage supply (for motor)
17 ERAH Erase signal
18,19,20 GND Ground
1-9

REV.-A
21---------3 1
Table 1-9 CN4 (Keyboard Interface) Pin Assignments
Ei0iiiiJj
22--------4 2
Pin No. Signal Name Definition
1 KSC 0 Key scan signal
2 KSC 1 Key scan signal
3 KSC 2 Key scan signal
4 KSC 3 Key scan signal
5 KSC 4 Key scan signal
6 KSC 5 Key scan signal
7 KSC 6 Key scan signal
8 KSC 7 Key scan signal
9 KSC 8 Key scan signal
10 KRTN 0 Key return signal
11 KRTN 1 Key return signal
12 KRTN 2 Key return signal
13 KRTN 3 Key return signal
14 KRTN 4 Key return signal
15 KRTN 5 Key return signal
16 KRTN 6 Key return signal
17 KRTN 7 Key return signal
18 LED 0 CAPS LOCK MODE
19
LED 1 NUMERIC MODE
20
LED
2 INSERT MODE
21,22
GND Ground
1-10

REV.-A
Table 1-10 CNS (LCD Interface) Pin Connections
15---------3 1
~
16--------4 2
Pin No. Signal Name Definition
1 VLD Circuit voltage:
+5
2 YDO Y data
3 YSCL Y
shift clock
4 YSPU Speed up signal
5 YDIS Y display signal
6
FS Frame signal
7 LP Latch pulse signal
8 XECL X enable clock
9 XSCL X shift clock
10 XDO X data 0
11
XD1 X data 1
12 XD2 X data 2
13
XD3 X data 3
14
GND Signal ground
15,16
VL Circuit voltage
* View from the rear side of the board.
Table 1-11 CNG (High Speed Serial Interface) Pin Connections
B~76
5 3
4
2 1
Pin No. Signal Name Definition
1 GND Signal ground
--
2 PTX Transmit data (output)
3
PRX Receiving data (input)
6
PIN Receiving mode (input)
7 POUT Transmit mode (output)
E
FG Chassis ground
1-11

Table 1-12 CN7 (RS-232C Interface) Pin Assignments
8~76 REV.-A
5 3
4
2 1
Pin No. Signal Name Definition
1 GND Signal ground
2
TXD Transmit data (output)
3 RXD Receiving data (input)
4 RST Request-to-send (output)
5 CTS Clear-to-send (input)
6 DSR Data
set ready (output)
7 DTR Data terminal ready (output)
8
CD Carrier detect
E FG Chassis ground
1-12

REV.-A
49 31
1:-=------------=--::1
Table 1-13 eN8 (Expansion) Interface
50
42
Pin Signal Direction Definition
No. Name
Pin Signal Direction Definition
No. Name
1
AB12
0 Address bus 12 2 AB11 0 Address bus
11
3 AB14
0 Address bus
14 4 AB13
0 Address bus 13
5 AB 1 0 Address bus 1 6 AB 2 0 Address bus 2
7
AB15
0 Address bus 15
8 AB 0 0 Address bus 0
9 AB 4 0 Address bus 4
10 AB 3 0 Address bus 3
11 AB 6 0 Address bus
~l 12 AB 5 0 Address bus 5
13 AB10
0 Address bus 10 14 AB 7 0 Address bus 7
15 AB 8 0 Address bus 8
16 AB 9 0 Address bus 9
17
DB 0 I/O Data bus 0 18 DB 1 I/O Data bus 1
19 DB
2 I/O Data bus 2 20 DB 3 I/O Data bus 3
21 DB 4 I/O Data bus 4 22 DB
5 I/O Data bus 5
23 DB 6 I/O Dat bus 6 24 DB 7 I/O Data bus 7
--
25
BURQ 0 Bus request
26 BUAK 0 Bus acknowledge
27 M1
0 Machine cycle 1 28 WAIT
I
Wait
29 Vl 0 Circuit voltage: +5V 30 HlTA
0 Halt acknowledge
31 GND -Signal ground 32 GND -Signal ground
33
RS
0 Reset 34 SPI I Speaker
-
35
RD
0 Read 36
MRQ 0 Memory request
-
37
WR 0
Write 38 ClK
0 2.45 MHz
39
VCH 0 Charging voltage
40
10RQ 0 I/O request
41
DCAS 0 Data CAS 42 DW 0 Data write
43
INTEX I External interruption
44 OFF
0 Initializilng signal
of IC "6A"
--
--
45
RXD I Serial received data 46 TXD 0 Serial send data
--
47 VB1
0 Battery voltage 48 BK2 I Bank exchange
49
CG
-Chassis ground 50
CG
-Chassis ground
1-13

REV.-A
Table 1-14 CN9 (Bar Code Read Interface) Pin Assignments
Pin No. Signal name
Definition
1 G Signal ground
2 +5 Circuit
voltage
3 BRDT
Barcode reader data
Table 1-15 CN10 (Analog Input Interface) Pin Assignments
Pin No. Signal name
Definition
1 G Signal
ground
2 ANIN
Analog input
3 TRIG
Analog trigger input
Table 1-16 CN11 (External Speaker Interface) Pin Assignments
Pin No. Signal name
Definition
1 EXSPG Speaker
ground
2 EXSP Speaker signal
1-14

REV.-A
1.5 Connection Cable (option)
Fig. 1-8 shows in a diagram the information cables for all the available peripheral devices.
PX-8
Option unit
#726
<px-_=:>
#724
Fig. 1-8 Peripheral Device Information Cables
Table 1-17 Information Cables Specific to the PX-8 Computer
No. Interface Part No.
#723 High speed serial
Y204080000 (Y204080400"'JAPAN)
#724
RS-232C
Y204080 100 (Y204080500"'JAPAN)
#725 RS-232C
Y204080200 (Y204080600"'JAPAN)
#726
High speed serial/RS-232C
Y204080300 (Y204080700"'JAPAN)
#727 Expansion interface
Y204301000
1 -1 5

REV.-A
(1) # 723 cable
Usage
Connection to dedicated floppy disk drive
Connector: Round-type miniature, DIN6
~
oo
00 0
00
Q'------"I=~----(lt---l -------t-mI...JJllWJ>-IIIIIIIII------'O G
No. Signal Name
Color
1 GND Black
~
2 PTX
Brown
No. Signal Name Color
3 PRX Red
1 PRX Red
4
--
-2
PIN Orange
5
--
-3 PTX
Brown
6 PIN Orange 4 POUT Blue
7 POUT Blue 5 GND Black
8
--
-6
-- -
E CGND (Shield) E CGND (Shield)
Fig. 1-9
# 723, simple serial cable, consists of two lines: the send/receive data line and the I/O control
line. Therefore, devices which can be connected via this cable are intelligent terminals only (that
is, dedicated floppy disk drives) that can be controlled by PIN, POUT.
(2) #
724 cable
Usage :
Connection to acoustic coupler
Connector: Round-type miniature, DB25
~
oo
00 0
00
1-16
JI