IBM 3278 Use and care manual

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IBM Personal Computer
3278/79 Emulation
Adapter Technical .
Reference
1502336

First Edition (October 1983)
Changes are periodically made to the information herein; these
changes will
be incorporated in new editions of this publication.
Products are
not stocked at the address below. Requests for
copies of this product and for technical information about the
system should be made to your authorized IBM Personal
Computer dealer.
A Reader's Comment Form is provided
at the back of this
publication.
If this form has been removed, address comments to
IBM Corporation, Personal Computer, P.O. Box 1328-C, Boca
Raton, Florida 33432. IBM may use
or distribute any of this
information you supply in any way it believes appropriate without
incurring any obligations whatever.
© Copyright International Business Machines Corporation 1983
ii

FEDERAL COMMUNICATIONS
COMMISSION RADIO FREQUENCY
INTERFEREN
CE STATEMENT
Warning: This equipment has been certified to
comply with the limits for a Class B computing
device, pursuant to Subpart J
of Part 15 of FCC
rules. Only peripherals (computer input/output
devices, terminals, printers, etc.) certified to comply
with the Class B limits may be attached to this
computer. Operation with non-certified peripherals
is
likely to result in interference to radio and TV
reception.
INSTRUCTIONS TO USER
This equipment generates and uses radio frequency
energy and if not installed and used properly, i.e., in
strict accordance with the operating instructions,
reference manuals, and the service manual, may cause
interference to radio
or television reception. It has been
tested and found to comply with the limits for a Class B
computing device pursuant to
Subpart J of Part 15 of
FCC Rules, which are designed to provide reasonable
protection against such interference when operated in a
residential installation.
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iv
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 or more of the
following measures:
• Reorient the receiving antenna.
• Relocate the equipment with respect to the receiver.
• Move the equipment away from the receiver.
• Plug the equipment into a different outlet so that
equipment and receiver are on different branch
circuits.
• Ensure that side option mounting screws, attachment
connector screws, and ground wires are tightly
secured.
• If peripherals not offered by IBM are used with this
equipment, it
is suggested that you use shielded,
grounded cables with in-line filters, if necessary.
If necessary, consult your dealer service representative
for additional suggestions.
The manufacturer is not responsible for any radio or TV
interference caused by unauthorized modifications to this
equipment. It
is the responsibility of the user to correct
such interference.
CAUTION
This product is equipped with a UL-listed and
CSA-certified plug for the user's safety. It is to be
used in conjunction with a properly grounded
receptacle
to avoid electrical shock.

Preface
This publication provides technical information about the IBM
Personal Computer 3278/79 Emulation Adapter Card. This
manual describes the hardware design and provides interface
information for the IBM Personal Computer and IBM Personal
Computer XT.
The information in this publication
is for reference, and is
intended for hardware and software designers, programmers,
engineers, and interested persons who need
to understand the
design and operation of the IBM Personal Computer.
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vi

Contents
Section 1. IBM Personal Computer 3278/79 Emulation
Adapter
........................................ 1-1
Introduction ................................. 1-1
Adapter Block Diagram
........................ 1-2
I/O Address Locations ......................... 1-3
Interrupt/Status Register (2DO) ................. 1-4
Visual/Sound Register
(2Dl) ................... 1-5
Cursor Address Register (2D2, 2D3)
............. 1-6
Control Register (2D4)
........................ 1-7
Scan Code Register (2D5)
...................... 1-9
Terminal ID Register (2D6)
................... 1-10
Memory Address Locations .................... 1-11
Accepted Commands
......................... 1-12
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viii

Section 1. IBM Personal Computer
3278/79 EmulationAdapter
Introduction
The IBM Personal Computer 3278/79 Emulation Adapter card
supports emulation
of the base 3270 data stream and controls
communication between the IBM Personal Computer and an IBM
control unit. All system control signals and voltage requirements
are provided through a 2
by 31 position card edge tab. A coaxial
connector (type
BNC) joins this adapter card to the control unit.
The adapter card will accept, decode, and execute commands
issued from the control unit
or the IBM Personal Computer. All
information from the control unit
is sent in the form of a 12-bit
frame over a coaxiallinlc Transition checks include mid-bit
transition and transmission parity.
1-1

Adapter BlockDiagram
Coax
line Interface
Personal
~
Transformer
~
Control
~
Control
Computer
~
Interface
~
,~
,If
Data Bus
~
),
~~
"
Buffer
'"
-
Buffer
~
Control
~
Adapter Block Diagram
1-2