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
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CHAPTER 1
GENERAL DESCRIPTION
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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

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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
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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

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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

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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

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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

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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