NorthStar HSIO-4 User manual

N o rttiS la r^
HSIO-4
HORIZON
Serial Input/O utput-
Four Port
USER/TECHNICAL MANUAL

NorfhSta^
North Star Computers, Inc.
14440 C a ta lin a St.. San Leandro, C A 94577 USA
(415) 3 5 7 -8 50 0 TWX/Telex (9 1 0 ) 366-7001
HSIO-4
HORIZON Serial Input/Output — Four Port
USER/TECHNICAL MANUAL
HORIZON® is a registered trademark of North Star Computers, Inc.
Copyright © 1981, by North Star Computers, Inc.
All Rights Reserved
00261B

TABLE OF CONTENTS
SECTION 1 GENERAL INFORMATION PAGE
1.1 Introduction 1
1.2 Warranty 2
1.3 Features of the HSIO-4 3
SECTION 2 INSTALLING THE HSIO-4
2.1 Unpacking the HSIO-4 4
2.2 Setting I/O Address Switches for
the North Star TSS/A 5
2.3 Configuration Changes 6
2.4 Completing Installation 7
SECTION 3 IMPLEMENTING HSIO-4 FEATURES 14
3.1 General Concepts 14
3.1.1 Establishing a Communication Link 15
3.1.2 HSIO-4 Board Layout 19
3.1.3 I/O Addresses 20
3.1.4 Interrupts 22
3.2 Asynchronous Operation 24
3.2.1 Configuring Port as Modem 24
3.2.2 Configuring Port as Terminal 25
3.2.3 Baud Rate Selection 26
3.2.4 Sample Program 29
3.2.5 Current Loop Operation 33
3.2.6 Buffer Full Signals 35

PAGE
3.3 Synchronous Operation 38
3.3.1 Fixed Baud Rate of 55.8KHz 39
A. Configuring Port as Modem 39
B. Configuring Port as Terminal 40
3.3.2 Programmable Baud Rates 41
A. Configuring Port as Modem 41
B. Configuring Port as Terminal 42
3.3.3 Programming Baud Rates 43
3.3.4 Alternative Baud Rates 45
3.3.5 Sample Program 46
3.4 Interrupts 50
3.4.1 Arming and Disarming Maskable
Interrupts 51
3.4.2 Arming the Synchronous Detect
Interrupt 53
3.4.3 Connecting the Interrupt Lines 54

SECTION 4 THEORY OF OPERATION
PAGE
56
4.1 Address Decoder 57
4.2 Data Buffers 58
4.3 Baud Rate Generator 58
4.4 Interrupt Header 59
4.5 I/O Port 60
4.5.1 USART 61
4.5.2 Configuration and Clock Headers 61
4.5.3 Baud Rate Select Register 62
4.5.4 Interrupt Select Register 63
SECTION 5 TROUBLESHOOTING 64
5.1 Creating a Test Diskette 65
5.1.1 Creating an Auto-Start DOS Diskette 65
5.1.2 Creating the Test Program 66
5.1.3 Configuring Basic for Auto-Start
Operation 68
5.2 Software Testing 69
5.3 Oscilloscope Testing 71
5.4 Repair Procedures 73
APPENDICES
A. RS-232 Connector Pin Assignments 74
B. Notes On The Interface To The USART
and USART Manufacturer Specification 75
92
C. HSIO-4 Parts List
D. Schematic Drawings 94

SECTION 1 GENERAL INFORMATION
1.1
INTRODUCTION
The HSIO-4 is a 4-port serial input/output
board designed for use with the HORIZON. It
can also be used with some other S-100 bus
systems.
This manual provides basic instructions on how
to install the HSIO-4 board in your HORIZON;
it also provides technical information and
detailed instructions for implementing a range
of HSIO-4 features and operating characteristics.
SECTION 1 describes HSIO-4 features and
capabilities and contains warranty
information.
SECTION 2 provides basic instructions on
how to unpack and install the HSIO-4 board
in a HORIZON.
SECTION 3 describes interface connections and
requirements; it also provides detailed
instructions on how to use the HSIO-4 to
establish communication links between the
HORIZON and a variety of peripheral devices.
SECTION 4 provides a functional block diagram
of the HSIO-4 and discusses the theory of
operation.
SECTION 5 provides troubleshooting procedures
to aid in isolating problems.
The APPENDICES furnish detailed technical
information, including schematic drawings,
RS-232 pin assignments, and a manufacturer data
sheet for the USART.
Every effort has been made to ensure the accuracy
of this manual. If you find errors or omissions
in this material or if you have suggestions on
how it can be improved, please write:
North Star Computers, Inc.
North Star Technical Services Group
14440 Catalina Street
San Leandro, CA 94577
North Star HSIO-4 1User/Technical Manual

1.2
WARRANTY North Star Computers, Inc., warrants the
electrical and mechanical parts and workmanship
of this product to be free of defects for a
period of 90 days from date of purchase. If
such defects occur, North Star Computers, Inc.,
will repair the defect at no cost to the
purchaser. This warranty does not extend to
defects resulting from improper use or assembly
by purchaser, nor does it cover transportation
to the factory. Also, the warranty is invalid
if all instructions included in the
accompanying documentation are not carefully
followed.
Should a unit returned for warranty repair be
deemed by North Star Computers, Inc. to be
defective due to purchaser's action, then a
repair charge (not to exceed $50 without
purchaser's consent) will be assessed. ANY
UNIT(S) OR PART(S) RETURNED FOR WARRANTY REPAIR
MUST BE ACCOMPANIED BY A DATED COPY OF THE
ORIGINAL SALES RECEIPT. The item should be
returned to the dealer from whom the product
was purchased, for implementation of the
warranty. When sending the item to the factory
for repair, the dealer must call the North Star
Technical Hotline to receive a Return Material
Authorization (RMA) number to accompany the
item to the factory. Terminals and printers are
covered under separate warranties.
The following warranty limitation applies to
units located outside the United States of
America: All costs and arrangements for
transportation of the product to and from the
factory are borne entirely by the customer.
No warranty, expressed or implied, is extended
concerning completeness, correctness, or
suitability of the North Star equipment for any
particular application. There are no warranties
which extend beyond those expressly stated
herein. This limited warranty is made in lieu
of all other warranties, expressed or implied,
and is limited to repair or replacement of the
product.
North Star HSIO-4 2User/Technical Manual

1.3
FEATURES OF THE HSIO-4
The HSIO-4 is a 4-port serial input/output
board designed by North Star Computers, Inc.,
for use with the HORIZON and North Star
multi-user systems. As supplied, the HSIO-4
is configured for use with the North Star
TSS/A Multi-User System for Application
Software. Additional capabilities provide
flexibility and permit operation in a variety
of hardware and software environments.
Synchronous/Asynchronous
The HSIO-4 provides four serial input/output
ports which may be configured for synchronous
or asynchronous communications.
Baud Rate Selection
Baud rates are programmable and may be
selected from among ten available
asynchronous baud rates and five available
synchronous baud rates. Simple wiring
changes provide additional baud rates.
Asynchronous Range: 75 baud to 19.2K baud
Synchronous Range: 1.76K baud to 55.8K baud
Mode Configuration
All four ports use RS-232 signal levels. A
hardware change permits 20mA current loop
operation. As supplied, each port is wired
for connection to a standard terminal or
printer. Each port has a configuration header
which may be changed to permit connection to a
modem or another computer.
Buffer Full Signals
The HSIO-4 accomodates printers and other
peripheral devices using 'buffer full'
signals.
Interrupts
Each port provides four sources of interrupt;
three are maskable, the fourth is armed by a
jumper. The resultant interrupt from each
port may be connected to any of the S-100 bus
interrupt lines.
North Star HSIO-4 3 User/Technical Manual

SECTION 2 INSTALLING THE HSIO-4
2.1
UNPACKING THE HSIO-4
The HSIO-4 board is shipped in a carton
containing:
1. North Star HSIO-4 board
2. Four ribbon cables
3. Plastic envelope containing eight
jackscrews, lockwashers, and nuts.
4. HSIO-4 User/Technical Manual
Examine the contents of the carton to make
sure they match this list. If anything appears
to be damaged due to shipping, please notify
your dealer immediately.
CAUTION
Before handling the board, you
should ground yourself to
discharge whatever static
electricity may have built up on
your body. The electronic
components on the board are
sensitive to static electricity.
So, just before you handle the
board, touch a grounded metal
object, such as the chassis of a
HORIZON that is plugged into a
wall outlet. This will prevent a
surge of static electricity from
damaging the components.
North Star HSIO-4 4User/Technical Manual

When handling the board, touch it only by the
edges to avoid bending pins on the components'.
If you lay the board down, put it on a flat
surface with the components facing up.
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Figure 2-1
2.2
SETTING I/O ADDRESS SWITCHES FOR THE NORTH STAR TSS/A
As supplied, the I/O address switches on the
HSIO-4 board are set for use with the North
Star TSS/A (Multi-User System for Application
Software). The I/O addresses for each port are
set by the four switches located in the upper
right corner of the board.
To make sure the switches have not been
inadvertently changed, check them against the
setting shown in Figure 2-3.
If you are using different software, refer to
Section 3 for instructions on how to set
the I/O address switches.
Figure 2-2
Figure 2-3
North Star HSIO-4 5User/Technical Manual

2.3
CONFIGURATION CHANGES
As supplied, the HSIO-4 is ready for
immediate connection to four asynchronous
RS-232 terminals or printers.
If you are using the North Star TSS/A
Multi-User System for Application Software
with asynchronous RS-232 terminals and
printers, the HSIO-4 can be installed directly
in the HORIZON without modification.
If you are using different software or using
hardware with different operating
characteristics, you may need to implement
configuration changes and/or programming
routines and should refer to Section 3
(IMPLEMENTING HSIO-4 FEATURES) for general
guidelines and specific instructions before
continuing this installation procedure.
IMPORTANT NOTE
Any necessary configuration
changes must be completed
BEFORE installing the HSIO-4
board in the HORIZON.
North Star HSIO-4 6User/Technical Manual

2.4
COMPLETING INSTALLATION
WARNING
Turn off the power switch on the
back of the HORIZON, and unplug the
power cord from the wall outlet
before you remove the HORIZON
cover. The high voltages used in
the computer can be dangerous
unless you observe this precaution.
Do NOT remove the cover from the
HORIZON until the power is off, the
fan has stopped, and the red
indicator light on the front panel
has fully dimmed.
Remove the four screws that hold the HORIZON
cover in place. Lift off the cover.
Hold the HSIO-4 board in one hand and touch
the metal chassis of the HORIZON with the
other hand. This will eliminate any difference
in static potential between the HSIO-4 board
and the computer.
Figure 2-4
North Star HSIO-4 7User/Technical Manual

Hold the board as shown in figure 2-5, with
the component side of the board toward the
front of the HORIZON. Slide the board into the
rear-most slot in the card cage. If that slot
is already occupied by another board, remove
that board and place it in an unused slot.
Figure 2-5
The row of metallic strips or "fingers" on the
bottom of the board should fit into the
connector at the base of the slot. Press
firmly on the top of the board to make sure it
is fully seated in the connector. The top of
the HSIO-4 board should be even with the other
installed North Star boards.
If a second HSIO-4 board is utilized, it
should be installed in the slot immediately in
front of the first HSIO-4 board.
North Star HSIO-4 '8 User/Technical Manual

Four flat ribbon cables are supplied with the
HSIO-4 board. You will notice that each cable
has a connector at either end. The Terminal/
Modem Mating Connector is shaped like an
elongated "D" and has curved corners. The
Board Mating Connector is rectangular.
Terminal/Modem Mating Connector
Board Mating Connector
Figure 2-6
Each Board Mating Connector must be plugged
into one of the four port connectors on the
HSIO-4; each Terminal/Modem Mating Connector
must be seated in one of the connector holes
in the back panel of the HORIZON.
It is recommended that you utilize the
outer-most column of connector holes, as
shown in Figure 2-7. The other column of
connector holes should be utilized only if a
second HSIO-4 board is installed.
North Star HSIO-4 9User/Technical Manual

Before connecting the cables, you should
number each connector hole on the HORIZON back
panel. For use with the TSS/A, the connector
holes should be numbered as shown in Figure
2-8.
Figure 2-8
From outside the back panel of the HORIZON,
thread each ribbon cable — rectangular Board
Mating Connector first — through a connector
hole. Gently pull the cable through until the
Terminal/Modem Mating Connector touches the
sides of the hole. From outside the back
panel, push firmly to seat the connector in
the hole.
Board Mating Connector
Terminal/Modem
Mating Connector
North Star HSIO-4 10 User/Technical Manual

Using the jackscrews provided, bolt the
D-connector in place, as shown in Figure 2-10.
From outside the back panel, insert each screw
through the connector mounting. Slip a
lockwasher over the screw, and secure it with
a nut.
Repeat these installation procedures for all
four ribbon cables.
North Star HSIO-4 11 User/Technical Manual

Taking care not to twist the cables, plug each
Board Mating Connector into the appropriate
26-pin header at the top of the HSIO-4 board.
See Figure 2-11. For use with the TSS/A, the
cables should be connected as follows:
J1 to Port 2
J2 to Port 3
J3 to Port 4
J4 to Port 5
Figure 2-11
North Star HSIO-4 12 User/Technical Manual

Gently flex each cable to fit it into the
space between the card cage and the back
panel, taking care to position the cables so •
they will not be crushed when you replace the
lid.
Replace the cover on the HORIZON, and replace
the screws.
Connect the terminals and/or printers to the
appropriate I/O port sockets on the HORIZON
back panel.
Plug the HORIZON line cord into the wall
outlet. Plug the power cords for all connected
terminals into the wall outlet. Turn on the
power switches for the HORIZON and all
terminals.
North Star HSIO-4 13 User/Technical Manual

SECTION 3 IMPLEMENTING HSIO-4 FEATURES
This section provides an overview of serial
data communication between computers and other
electronic devices; it also provides detailed
instructions on how to use the HSIO-4 to
establish communication links between the
computer and a variety of periperal devices.
As supplied, the HSIO-4 is ready for immediate
connection to four asynchronous RS-232
terminals or printers. Connection to most
asynchronous terminals and printers usually
requires no configuration changes to the
HSIO-4. Reading through the discussion that
follows can help you to determine what, if
any, changes are required by the particular
hardware and software you are using. Once you
have identified the needed modifications, you
should consult the appropriate subsection for
specific, detailed instructions.
3.1
GENERAL CONCEPTS
In order to transmit data between a computer
and another electronic device, a communication
link must be established. Such a communication
link is usually comprised of a cable with a
connecting plug at each end. One plug is
connected to an Input/Output (I/O) port in the
computer; the other is connected to an I/O
port in the electronic device.
COMPUTER
TRANSMITTER
I/O PORT
RECEIVER
RECEIVER
I/O PORT
TRANSMITTER
DEVICE
Figure 3-1
North Star HSIO-4 14 User/Technical Manual

3.1.1
ESTABLISHING A COMMUNICATION LINK
To establish a communication link between two
electronic devices (such as a computer and a
terminal), the operating characteristics of
both devices must be compatible.
The HSIO-4 has four serial I/O ports. Each
I/O port provides the interface necessary to
establish a communication link between a
HORIZON computer and another electronic device
with a compatible serial I/O port.
RS-232 OR 20mA CURRENT LOOP SIGNALS
Most computers, terminals, and printers use
RS-232 signals. A few commercially used
terminals, such as teletypes, use 20mA
current loop signals.
As supplied, each HSIO-4 port is wired to
use RS-232 signals. 20mA current loop signals
can be accomodated with a configuration
change. Refer to section 3.2.5 for specific
instructions.
ASYNCHRONOUS OR SYNCHRONOUS TRANSMISSION
Each port on the HSIO-4 allows two different
types of data transmission: asynchronous and
synchronous. Typical communication between a
computer and a terminal is asynchronous.
Synchronous communication is used primarily to
facilitate high-speed computer-to-computer
data transmission.
ASYNCHRONOUS
See Section 3.2 for specific configuration
and programming instructions. As supplied,
each port on the HSIO-4 is configured for
asynchronous operation.
SYNCHRONOUS
To operate an I/O port in synchronous mode,
you must wire the Configuration Header and
the Clock Header, and then program the I/O
port according to the specific procedures in
Section 3.3.
North Star HSIO-4 15 User/Technical Manual