NEC Advanced Personal Computer User manual

NEe

.... ~ Advanced
A~"'Personal Computer
TM
APe System Reference Guide
NEe
NEe Information Systems, Inc.
819-000100-1003
4-83

LIMITED WARRANTY
AND
LIABILITY DISCLAIMER
NEC Information Systems, Inc. products are warranted in accordance with the
terms
of the applicable NEC Information Systems, Inc. products specification.
Product performance is affected bysystemconfiguration, software, the application,
customer
data, and operator control of the system among otherfactors. While NEC
Information Systems, Inc. products are considered to be compatible with most
systems, the specific functional implementation by customers
of the products may
vary.
Therefore, the suitability
of a product for a specific application must be determined
by the customer
and is not warranted by NEC Information Systems, Inc.
This
manual is as complete and factual as possible at the time of printing, however,
the information
in this manual may have been updated since that time. NEC
Information Systems, Inc. reserves the right to change the functions, features, or
specifications of its products at any time, without notice.
NEC Information Systems, Inc. has prepared this document for use by NECIS
employees
and customers. The information contained herein is the property of
NECIS and shall not be reproduced in whole or in part without prior written
approval from NECIS.
First Printing -September 1982
Revised -December 1982
Revised -March
1983
Copyright 1982
NEC Information Systems, Inc.
5 Militia Drive
Lexington,
MA 02173
Printed in U.S.A.

FEDERAL COMMUNICATIONS COMMISSION RADIO
FREQUENCY INTERFERENCE STATEMENT
"w ARNING: This equipment generates, uses and can radiate radio frequency
energy
and if not installed and used in accordance with the instructions manual,
may cause interference to radio communications. It has been tested and found to
comply with the limits for a Class A Computing device pursuant to Subpart] of
Part 15 of FCC Rules, which are designed to provide protection against such
interference. Operation of the equipment in a residential area is likely to cause
interference in which case, the user will be required to take whatever measures may
be
required to correct the interference."
Manufacturer's Instructions and User's Responsibility
to Prevent Radio Frequency Interference
Manufacturer's Instructions
The user must observe the following precautions when installing and operating this
device:
1. Operate the equipment in strict accordance with the manufacturer's
instructions for the model.
2.
Ensure that the unit is plugged into a properly grounded wall outlet and
that the power cord supplied with the unit is used and not modified.
3. Ensure
that the unit is always operated with the factory-installed cover set
on the unit.
4.
Make no modifications to the equipment which would affect its meeting the
specified limits
of the Rules.
5.
Properly maintain the equipment in a satisfactory state of repair.
User's Responsibility
The user has the ultimate responsibility to correct problems arising from harmful
radio-frequency emissions from equipment under his control. If this equipment
does cause interference to radio or television reception, which can be determined by
turning the equipment off and on, the user is encouraged to try to correct the
interference by
one of the following measures. All of these responsibilities and any
others not mentioned are exclusively at the expense of the user.
111

iv
1. Change in orientation of the receiving device antenna.
2. Change in orientation of the equipment.
3. Change in location
of equipment.
4. Change in equipment
power source.
If these attempts are unsuccessful, install one or all of the following devices:
1. Line isolation transformers
2. Line filters
3. Electro-magnetic shielding
If necessary, the user should consult the dealer, NEC, or an experienced radioltele-
vision technician for additional suggestions. The user may find the following
booklet prepared by the Federal Communications Commission to be helpful: "How
to Identify and Resolve Radio-TV Interference Problems." This booklet is available
from the U.S.
Government Printing Office, Washington, D.C. 20402, Stock No.
004-000-00345-4.
"N ote: The operator of a computing device may be required to stop operating his
device
upon finding that the device is causing harmful interference and it is in the
public interest
to stop operation until the interference problem is corrected."

Contents
Page
PREFACE ...................................................... Xlii
CHAPTER 1 HARDWARE OVERVIEW
CHAPTER 2
PROCESSOR PCB
2.1 MOTHER BOARD/CARD CAGE INTERFACE ......... 2-3
2.2 MICROPROCESSOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-13
2.3 DIRECT MEMORY ACCESS .......................... 2-14
2.4
INTERVAL TIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-19
2.5 INTERRUPT CONTROL. . . . . . . . . . . . . . . . . .. . . . . . . . . . .. 2-20
2.6 MEMORY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-26
2.6.1 Main
Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-27
2.6.2 Battery-Backed
Memory. . . . . . . . . . . . . . . . . . . . . . .. 2-28
2.6.3 Read Only Memory
............................ 2-29
2.7
PARALLEL PRINTER CONTROL ...................... 2-29
2.7.1 Interface
...................................... 2-29
2.7.2 Programming
Considerations. . . . . . . . . . . . . . . . . . .. 2-29
2.8
KEYBOARD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-38
2.8.1 Keyboard Layout
and Scan Codes. . . . . . . . . . . . . . .. 2-39
2.8.2
Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-41
2.9 CALENDAR AND CLOCK GENERATOR .............. 2-42
2.9.1 Circuit
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-43
2.9.2 Programming
Considerations. . . . . . . . . . . . . . . . . . .. 2-44
2.10 JUMPER SETTINGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-44
CHAPTER 3 CONTROLLER PCB
3.1 MOTHER BOARD/CARD CAGE INTERFACE ......... 3-1
3.2 CRT DISPLAY CONTROL ............................ 3-4
3.2.1 Display Buffer
Memory. . . . . . . . . . . . . . . . . . . . . . . .. 3-5
3.2.2 Programming
Considerations. . . . . . . . . . . . . . . . . . .. 3-8
3.3
CRT DISPLAY UNIT ................................. 3-18
3.4
FLEXIBLE DISK DRIVE CONTROLLER. . . . . . . . . . . . . .. 3-21
3.4.1 Programming Considerations. . . . . . . . . . . . . . . . . . .. 3-24
3.4.2 Drive A
and B Interface. . . . . . . . . . . . . . . . . . . . . . . .. 3-37
v

Contents (cont'd)
Page
3.5 FDD UNIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-39
3.5.1 Specifications
................................. , 3-39
3.5.2
Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-40
3.5.3 Terminations and Jumper Settings. . . . . . . . . . . . . . .. 3-40
3.6 SERIAL I/O COMMUNICATIONS CONTROLLER ..... , 3-43
3.6.1 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 3-43
3.6.2 Circuit
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-43
3.6.3 Interface
..................................... , 3-43
3.6.4 Programming Considerations
................... , 3-43
3.6.4.1 Asynchronous Operating Mode
.................. 3-50
3.6.4.2 Synchronous Operating Mode ................... 3-53
3.6.4.3 Business Machine Operating Mode
............... 3-57
3.6.5 Status
Word Format ........................... 3-59
3.7
SOUND CONTROL .................................. , 3-60
3.7.1 Interface ...................................... 3-61
3.7.2 Programming Considerations. . . . . . . . . . . . . . . . . . .. 3-62
3.8
ARITHMETIC PROCESSING UNIT. . . . . . . . . . . . . . . . . . .. 3-62
3.9
JUMPER SETTINGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-64
CHAPTER 4 POWER SUPPLY
APPENDIX A INTEGRATED CIRCUIT DATA SHEETS
Al 16-BIT MICROPROCESSOR ........................... AI-I
A2 PROGRAMMABLE COMMUNICATION INTERFACES .. A2-1
A3
SINGLE/DOUBLE DENSITY FLOPPY DISK
CONTROLLER ....................................... A3-1
A4
GRAPHICS DISPLAY CONTROLLER .................. A4-1
APPENDIX B LOGIC AND SCHEMATIC DIAGRAMS
VI

Contents (cont'd)
APPENDIX C PROGRAMMABLE ARRAY LOGIC DECODING
SPECIFICATIONS
APPENDIX D CHARACTER CODE AND KEYBOARD
INFORMATION
APPENDIX E 110 PORT ADDRESSES AND INSTRUCTIONS
APPENDIX F HARDWARE
SPECIFICATIONS
Vll

List of Illustrations
Figure Title Page
1-1 System Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-2
2-1 Processor PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-1
2-2 Processor PCB Block Diagram .............................. 2-2
2-3 Mother
Board/Card Cage Intp.rface . . . . . . . . . . . . . . . . . . . . . . . . .. 2-3
2-4 Processor
Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-8
2-5
DMA Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-9
2-6
RD Y Signal Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-10
2- 7 RFSH Signal Timing ...................................... , 2-10
2-8 Processor Tnterface Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-11
2-9 Device Interface Circuits
................................... 2-12
2-10
DMA Command and Mode Registers ........................ 2-16
2-11
DMA Request and Mask Register. . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-17
2-12
DMA Status Register ...................................... 2-19
2-13 Interval Timer Block
Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-19
2-14 Interrupt Control Block Diagram
............................ 2-21
2-15 Interrupt Initialization
Command Words ..................... 2-24
2-16 Interrupt Operation
Command Words ............ , ........... 2-25
2-17 System Memory
Map ...................................... 2-26
2-18 Main Memory Block Diagram
............................... 2-27
2-19 Battery-Backed Memory Block Diagram
...................... 2-28
2-20 Parallel Printer Control Block Diagram ....................... 2-30
2-21 Parallel Printer Cable Connections ........................... 2-32
2-22 Parallel Printer Controller Interface Timing
................... 2-36
2-23 Parallel Printer Controller Interface at Paper
Out Status ........ 2-37
2-24 Keyboard Block Diagram
................................... 2-38
2-25 Keyboard Layout
.......................................... 2-39
2-26 Keyboard Interface
........................................ 2-41
2-27
Clock/Calendar Block Diagram ............................. 2-43
2-28
Clock/Calendar Format .................................... 2-45
2-29 Proce<:sor PCB
Jumper Settings .............................. 2-46
3-1 Controller PCB ..........................•................ 3-2
3-2 Controller PCB Block Diagram
.............................. 3-3
3-3
CRT Display Control Block Diagram ........................ 3-5
3-4 Character-Code Representation in the
Character Code
Buffer Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 3-5
Vlll

List of Illustrations (cont' d)
Figure
3-5
3-6
3-7
3-8
3-9
3-lO
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-20
3-21
3-22
3-23
3-24
3-25
3-26
3-27
3-28
3-29
4-1
4-2
D-l
D-2
D-3
Title
Bit Map for Character Attribute Code ....................... .
Display Buffer Memory
Map ............................... .
Relationship Between
Character Code, Character-Attribute Code,
Display Position, and Video Screen ......................... .
GDC Status Register Bit Map .............................. .
Monochrome-CRT Display Interface ........................ .
Color-CRT Display Interface ............................... .
FDC Block Diagram ...................................... .
FDC Timing Diagram .................................... .
FDD Signal Connector Interface and Pin Assignments ......... .
FDD Power Connector Interfce and Pin Assignments .......... .
FDD Termination Resistor Modules, Location
and Installation .......................................... .
FDD Jumper, Location and Proper Setting .................. .
Serial
I/O Communications Controller Block Diagram ........ .
Communications Controller Cable Connections ............... .
Asynchronous Mode Instruction Word ...................... .
Command Instruction Word Format ........................ .
Communications Controller, Circuit for
Asynchronous Operation .................................. .
Synchronous Mode Instruction Word ....................... .
Communications Controller, Circuit for Synchronous Operation
Using External Clock ..................................... .
Communications Controller, Circuit for Synchronous Operation
Using Internal Clock ...................................... .
Communications Controller, Circuit for
Business Machine Clock
................................... .
Communications Controller, Status Word Format ............ .
Sound Control Block Diagram ............................. .
Location of Sound Interface Connectors ..................... .
Controller PCB Jumper Settings ............................ .
System
Power Supply Block Diagram ....................... .
Power Supply Interconnection Diagram ..................... .
APC GRPH 1 Characters .................................. .
APC GRPH2 Characters .................................. .
Keyboard Layout Showing Hex Codes
for Special Keys .......................................... .
Page
3-6
3-7
3-8
3-9
3-19
3-20
3-22
3-24
3-41
3-42
3-42
3-43
3-45
3-49
3-51
3-51
3-52
3-54
3-54
3-55
3-57
3-59
3-60
3-61
3-65
4-2
4-3
D-6
D-7
D-8
IX

x
List of Tables
Table
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-lO
2-11
2-12
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-lO
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-20
3-21
Title Page
Card Cage Socket Contact Assignments . . . . . . . . . . . . . . . . . . . . .. 2-4
DMA Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-14
Timer Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-20
Interrupt Lines ........................................... 2-21
Interrupt Control Commands Summary. . . . . . . . . . . . . . . . . . . . .. 2-22
Parallel Printer Connectors Pin Assignments. . . . . . . . . . . . . . . . .. 2-31
Parallel Printer Interface Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-33
Parallel Printer Controller Instruction. . . . . . . . . . . . . . . . . . . . . . .. 2-35
Parallel Printer Controller Instruction Sequence . . . . . . . . . . . . . .. 2-36
Keyboard Scan Codes ..................................... 2-39
Keyboard Interface Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-42
Clock/Calendar Instruction Format ......................... 2-44
Attribute Description for Character Attribute Code ............ 3-6
GDC I/O-Address and Bit Map ............................. 3-9
Contents of the GDC Status Register ........................ 3-lO
GOC Symbols ............................................ 3-11
GOC Commands ......................................... 3-14
GDC Command Constants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-18
Bit Description
of the FDC Main Status Register .............. 3-23
FOC Symbols ............................................ 3-24
FDC Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-27
FDC Status Register 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-33
FOC Status Register 1 ..................................... 3-34
FDC Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-35
FDC Status Register 3 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-36
FDC Register I/O Addresses and Functions .................. 3-36
Output Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-37
Input Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-38
FDD Specifications ....................................... 3-39
Serial
I/O Communications Controller Specifications .......... 3-44
Serial
I/O Commands ..................................... 3-46
Serial
I/O Connector Pin Assignments .................... .... 3-47
Serial
I/O Device Interface Connector
Pin Descriptions .......................................... 3-48

List of Tables (cont'd)
Table
3-22
3-23
3-24
3-25
3-26
3-27
3-28
3-29
4-1
C-l
C-2
C-3
C-4
C-5
D-l
D-2
D-3
D-4
E-l
E-2
E-3
E-4
E-5
E-6
Title Page
8251A Instruction ......................................... 3-50
Communications Controller, Baud Rate Coding During
Asynchronous Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-53
Communications Controller,
Baud Rate Coding During
Synchronous Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-56
Communications Controller, Baud Rate Coding
During
Operations with Business Machine Clocking .................. 3-58
Sound Interface Pin Assignments ............................ 3-61
Sound Programming Read/Write Format. ................... , 3-62
Sound Control Commands ................................. 3-62
Sound Scale Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-63
Power Supply Pin Command Assignments .................... 4-4
Identification
and Location of PAL Device ................... C-l
PFBOIB Inputs/Outputs ................................... C-2
PFB02B Inputs/Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. C-3
PFCOI Inputs/Outputs .................................... C-4
NMS02 Inputs/Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. C-5
Code Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. D-2
ASCII Special Characters .................................. D-3
APC Special Characters .................................... D-4
Quick Reference
Guide for ASCII Special Character/ APC Spe-
cial Character Association. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. D-5
I/O Port Address and Instructions for the DMA Controller. . . .. E-2
I/O Port Addresses and Instructions for the Interrupt
Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. E-4
I/O Port Addresses and Instructions for the Internal Timer ..... E-5
I/O Port Addresses and Instructions for the Serial I/O Commun-
ications Controller Number 1 ............................... E-6
I/O Port Addresses and Instructions for the Serial I/O Commun-
ications Controller Number 2 ............................... E-6
I/O Port Addresses and Instructions for the DMA Address
Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. E-7
E-7
I/O Port Addresses and Instructions for the CRT Controller .... E-7
xi

List of Tables (cont'd)
Table
E-8
E-9
E-10
E-11
E-12
E-13
E-14
E-15
E-16
E-17
Title Page
110 Port Addresses and Instructions for the Graphics Display
Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. E-8
110 Port Addresses and Instructions for the Keyboard
Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. E-8
110 Port Addresses and Instructions for the FDD Controller. . .. E-8
110 Port Addresses and Instructions for the Clock and
Calendar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. E-9
110 Port Address and Instruction for the BBM Enable ......... E-9
110 Port Addresses and Instructions for the APU . . . . . . . . . . . . .. E-9
110 Port Address and Instruction for the Power Off Control .... E-9
110 Port Addresses and Instructions for the Sound Control ..... E-10
110 Port Addresses and Instructions for the Timer. . . . . . . . . . . .. E-1O
110 Port Addresses and Instructions for the ODA Controller
Number 1 ................................................ E-ll
E-18 110 Port Addresses and Instructions for the IDA Controller. . . .. E-ll
E-19 110 Port Addresses and Instructions for the Communications
Adapter ................................................. E-12
E-20 110 Port Addresses and Instructions for the ASOP Controller ... E-12
xu

Preface
This system reference guide provides hardware design and interface information for
programmers, engineers, designers, and others who need to know how the APC is
designed.
Chapter 1, Hardware Overview, familiarizes you with the Advanced Personal Com-
puter and defines the principal components and devices.
Chapter 2, Processor PCB, includes descriptions and technical information for the
devices
contained on the Processor PCB along with programming considerations
where appropriate.
Chapter 3, Controller PCB, includes information similar to that in Chapter 2 for the
devices
contained on the Controller PCB.
Chapter 4, Power Supply, contains detailed specifications for the system power
source.
Appendices A
to F include hardware reference information such as IC data sheets,
logic
diagrams, and data summaries.
Xlll

List of Abbreviations
A Ampere
ISR
Read Inservice Register
ALE Address Latch Enable KB Kilobyte
APC Advanced Personal
LED
Light Emitting Diode
Computer
LSB Least Significant Bit
APU Arithmetic Processing Unit
LSI Large-Scale
Integration
AT Abnormal Termination
MB Megabyte
BBM Battery-Backed
Memory
MFM
Modified Frequency
CMOS Complementary Metal Modulation
Oxide Semiconductor
MHz
Megahertz
CPU Central Processing Unit
MOS Metal Oxide
CRT Cathode Ray Tube Semicond uctor
CS
Code Segment ms Millisecond
DCH Device Control
MSB
Most Significant Bit
DIP Dual In-line Package ns Nanosecond
DMA Direct Memory Access
NT
Normal Termination
DMC Direct Memory Access
OCW
Operational Command
Cycle
Word
OS Data Segment
ODA
Output Device Adapter
EPROM Erasable Programmable
PAL Programmable Array
Read-Only Memory
Logic
ES Extra Segment PCB Printed Circuit Board
FDC Flexible Disk Drive
POF
Power Off Control
Controller
RAM
Random Access Memory
FDD Flexible Disk Drive
ROM Read-Only Memory
FIFO First-In First-Out
rpm Revolutions Per Minute
FM Frequency Modulation
SS
Stack Segment
GDC Graphic Display Controller
SW
Switch
HEX Hexadecimal
TTL
Transistor/Transistor
Hz Hertz Logic
IC
Integrated Circuit,
USART
Universal Synchronous/
Interrupt Code, Invalid
Asynchronous Receiver/
Command
Transmitter
ICW Initialization Command
V Volt
Word
VFO
Variable Frequency
I/O Input/Output Oscillator
IP Instruction Pointer
W
Watt
IRR
Read Interrupt Register
JlS
Microsecond
xiv

Chapter 1
Hardware Overview
The NEC Advanced Personal Computer (APC) has two basic components: a Main
Unit and a Keyboard. The Keyboard, which cable-connects to the Main Unit, is
common to all APC models. The Main Unit, which houses the Central Processing
Unit (CPU), memory, visual display, sound output, and peripheral controllers, is
available in three models: (I) a Monochrome Cathode Ray Tube (CRT) Display
with one 8-inch Flexible Disk Drive (FDD), (2) a Monochrome CRT Display with
two 8-inch FDDs, and (3) a Color CRT Display with two 8-inch FDDs. Several
options and accessories are available to enhance performance or to adapt the APC
for special applications.
Figure 1-1 is a block diagram of the APe. The Main Unit, the heart of the APC, has
a
CRT Display, one or two 8-inch FDDs, an ON/OFF switch, and several controls
associated with the CRT Display. Three Input/Output (I/O) cable connectors are
available
at the rear of the cabinet.
The CPU, memory, and basic control logic are contained in the Main Unit on two
quad-layered Printed Circuit Boards (PCB): a Processor PCB (G9PFBU) and a
Controller PCB (G9PFCU). These PCBs plug into a mother board interface bus
that has the space and power for up to three additional (optional) PCBs.
The Processor PCB contains as standard equipment:
• A 16-bit 8086 Microprocessor
• An 8288 Bus Controller with 20-bits of addressing, making one megabyte
(MB)
of memory accessible
• 128 kilobytes (KB) (standard) of Random Access Memory (RAM)
• 8 KB of Read-Only Memory (ROM)
• 4 KB of CMOS Battery-Backed Memory, which remains refreshed for at
least two years without ac power
• A 4-channel Direct Memory Access (DMA) Controller
1-1

Hardware Overview
1-2
\1.'\I~ LJNIT
r
I
I
PO\\'ER Sl'PPLY
5 LPiELS
SySTEM CLOCK
(4.9152!\.UIz)
'VIKROPROO.SSOR
(8086)
RAM
nYNAMIC MEMOR\
(pPD4164)
128 KB
I
B,I"THRY-SACKED
MEMOR\
(pPD449)
4 KB
Rf<A.D ONLY MUIIORY
(2732)
8 KB
TIMER
(8253)
BATTERY-BACKED
CAU;NDAR A~()
CLOCK CO"- I ROL
PRO( ESSDR PCB ((;9PFBl)
Figure 1-1 System Block Diagram
• A IS-channel Interrupt System
• Printer and Keyboard Controllers
-----l
4 CHA~NEL DMA
(8237)
15 CHA~"'EL INTR
(8259)
PARALLEL BUS
I
I
I
I
"RINTER CONTROL J--- I
(8255)
KDnOARD CON'IROL
--~
AUER~A1E
I/O CONTROLLER~
(OPTlO"'iALj
• Calendar-and-Clock Controller, which keeps track of the month, date, day
of week, hour, minute, and second, and runs on battery power when ac
power is off, thus preserving the time/date setting.
The Controller PCB contains as standard equipment:
• CRT Display Control, which can generate 250 predefined characters and
allows you to create and store on disk any number of sets of 256 other
special characters
NEe MODEL AP(
DOT MHRIX PR Ir"I I ER
NEt SPINWRIHR MODEL 3530
Ft LLY FORMED CHARAClER
PRINTER
MODEM OR OTHER
RSB2 ASYNCURO"'Ol S,
SY"CHRO~OL'S.
OR IWSI'\ESS
"'ACHINt: DFVI(T

• Flexible Disk Drive Controller (FDC) to coordinate the reading of and the
writing
to one or ~wo 8-inch flexible disks
• Alarm and Music Sound Programming System, which enables you to select
alarm tones and generate music across two octaves, with selected tempos,
volumes, and tone characteristics
• Serial Communications Adapter, which is a Universal Synchronous/
Asynchronous Receiver/Transmitter (USART), enabling the APC to
. communicate with almost any type of communications device.
The APC power supply is a 100-watt, 5-voltage-level switching regulator. It fur-
nishes dc levels
to all components -except to the CRT which has its own power
unit - and has sufficient reserve capacity to handle future expansion. The power
supply has a software-controlled Power-Off control (POF) circuit that enables you
to turn off the system locally or remotely.
One or two 8-inch FDDs are integrated into the Main Unit. The FDC (NEC
pPD765) can read from or write to dual-sided double-density disks (which store up
to 1MB of unformatted data) or single-sided single-density flexible disks(which can
store about 260 KB of unformatted data). The disk drive is a compact, high-
performance, energy-efficient design featuring direct drive by a dc motor. Head
loading and positioning is microprocessor-controlled for greater accuracy and
minimum wear and damage to the media surface. Variable Frequency Oscillation
(VFO) is employed to improve data transfer.
The APC comes equipped with a 12-inch (diagonal) green-phosphor monochrome
CRT or a 12-inch 8-color CRT. Either unit has a self-contained power supply. Both
have a reduced glare surface and a high resolution screen. Standard alphanumeric
characters are composed from an 8-by-19 dot matrix, allowing a display of25 lines
of80 characters. Special symbols can be designed by the user with a dot matrix of up
to 8-by-16.
The CRT Display has considerable versatility and provides you with capabilities for
scrolling, partitioning (and scrolling within selected partitions), overbar, vertical
bar, underscore, highlighting, blinking, and reverse video. The Color CRT Display
has all these attributes plus a choice from eight colors.
With the special-character generator, you can design up to 256 characters dot-by-
dot, which can be saved on disk as one or more special character sets. Using a dot
matrix printer, these special characters can be printed and displayed, making the
APC especially adaptable to users who use non-Roman alphabets or scientific
symbols.
Hardware Overview
1-3

Hardware Overview
1-4
The APC also offers an optional Graphics Adapter based on the NEC pPO 7220.
This self-contained single PCB plugs into the Main Unit and simplifies graphics
applications, such as area shading, simulated movement, and solid or dashed lines,
either straight or curved. By employing the Graphics Adapter with selected soft-
ware
packages, you can generate graphs, bar graphs, and three~dimensional
pictures. .
Also optional are two NEC printers. The Dot Matrix Printer provides rapid, high
quality printing at a low cost. It prints in both directions at 100 characters per
second on a 80-to-136-character column width. It prints special and graphic charac-
ters as well as standard alphanumeric characters.
The other printer is the NEC Model 3530 Spinwriter®, which produces high quality
fully-formed characters. This printer features interchangeable print elements that
contain up to 128 characters and are offered in several dozen type styles and symbol
sets.
It prints 35 characters per second at 10, 12, and 15 characters per inch or
proportional spacing. It also prints bidirectionally and offers word processor
functions, such as automatic underlining, shadowing, bold face printing, as well as
several
paper-handling accessories.
The standard APC comes equipped with 128 KB of RAM, which resides on the
Processor PCB. With the optional memory-expansion kits, RAM can be expanded
to 640 KB.
The asynchronous, synchronous serial I/O communications adapter is a standard
feature of the APC. The interface is supported by the NEC 8251A Communications
Controller, a USART, that is used as a peripheral and is programmed by the
microprocessor to communicate using virtually any serial or parallel data-
transmission technique, at programmable baud rates. For communications inter-
face
requirements beyond this standard controller, NEC offers special-purpose I/O
Controllers on plug-in boards.
The Keyboard is not housed in the Main Unit; it attaches to the rear of the Main
Unit with a single five-foot, coiled cable. The Keyboard has 109 keys, including a
numeric keypad and 22 programmable function keys that facilitate data and word
processing.
Each function key has two shift-modes, making available 44 user-
definable
functions with one or two keystrokes.
NOTE
Only 32 of the 44 user-definable functions can be character strings.

Chapter 2
Processor PCB
The Processor PCB (G9PFBU) fits vertically in the Main Unit and is 11 inches long
by
9Y2 inches high (see Figure 2-1). It is composed of four sandwiched layers,
including the signal, ground, and dc-power internal planes. It plugs into the third
slot of the card cage with a IOO-contact edge connector on the bottom of the PCB.
INTR
DMA
CO'lTROLLER
8086
PROCESSOR
RO:vI
CMOS
BATTERY·
BACKED
MEMORY
I
I
~---
~o::=;r::=:::;r=='ir====iIC~=,o
oDQ OOTMIO
c:::::I~:::::; 0 ('II
00 0
D0 Dog
~CJ[~hn
D oTM4
CJO
DO
DO
c::::JO
Cl OODOc::::J D
ODODDDD
ODD D D DO
ODD D D 00 ...
O~ D ~ 0 ~ 0 (S
DDDDD=D
ODD 0 DO
ODD 0 0 DO
DOD 0 DOD
G9PFBU
:vIAl'! MEMORY
Figure 2-1 Processor PCB
BATTERY POWER
SLPPLY CO'l'lECTOR
PARALLEL PRI"fI lOR
I'ITERF,CE
(O'l'lECTOR
RED LED
KEYBOARD
INTERFACE
COI\I\ECTOR
GREEN LED
11 in.
As shown in Figure 2-1, three cable connectors are on the Processor PCB; two are
26-pin connectors and the third is a 2-pin header connector. The Keyboard interface
uses
one of the 26-pin connectors, while the other connector provides a parallel
printer (or other such device) interface. Battery power is supplied by the 2-pin
connector.
2-1