DDS DELTA 1 User manual

DELTA 1
VIDEO DISPLAY TERMINAL
REFERENCE MANUAL
Delta
Data
Systems
Corporation
Woodhaven Industrial Park. Cornwells Heights. Pa.19020 • Phone (215] 639 - 9400

DELTA 1
VIDEO DISPLAY TERMINAL
REFERENCE
MANUAL
September 1969

DELTA 1
VIDEO DISPLAY TERMINAL

1.0
1.1
1.2
1.3
1.4
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.4.1
4.0
4.1
4.2
4.3
5.0
5.1
5.2
5.3
5.3.1
5.3.2
5.3.3
5.3.4
5.3.5
5.4
5.4.1
5.4.2
5.4.3
5.5
5.5.1
TABLE OF CONTENTS
Introduction
Selective Blink
Editing Package
Remote Programming
Cursor Controls
Systems Configuration
Display Control
Display
Read-Only Memory
Memory Control
Refresh Memory
Edit Control
Serial I/O Control
Parallel I/O Controller
Keyboard
Modes of Operation
Conversation Mode
Format Mode
Normal Mode
Graphic Mode
Light Pen Tracking
TV Compatibility
Use with CCTV Equipment
Raster Scan
Sync Signal and Composite Video
Input-Output Transfer
Party Line I/O Bus
Commands
Transmit Commands
Transmit Message
Transmit Display Command
Transmit Line Command
Transmit X Address Counter
Transmit Y Address Counter
Clear Commands
Clear Message Command
Clear Display Command
Clear Line Command
Enter Commands
Enter

5.5.2
5.5.3
5.6
5.6.1
5.6.2
5.6.3
5.6.4
5.7
5.7.1
5.7.2
5.7.3
5.7.4
5.7.5
5.7.6
5.7.7
5.7.8
5.7.9
5.7.10
5.7.11
5.8
5.9
6.0
6.0.1
6.0.2
6.1
6.1.2
6.1.3
6.1.4
6.1.4.1
6.1.4.2
6.1.5
6.2
6.2.1
6.2.2
6.3
6.3.1
6.3.2
6.3.3
6.3.4
6.3.5
7.0
7.1
Enter Addressed Line
Enter Addressed position
Edit Commands
Insert Command
Insert Line Command
Delete Command
Delete Line Command
Display Controls
Set Blink
Clear Blink
Cursor Left
Cursor Right
Cursor Up
Cursor Down.
Return
New Line
Home
Backspace
Tab
Party Line Signals
Interrupt System
Serial Communications
Communication Interface
Synchronous Interface
Serial Controller - IBM Compatible
ASCII Communication Control Characters
Addressing Sequences
Sequence/Response Dialogue
Transmit Data Commands
Enter Data Commands
Error Control
Teletype Compatibility Serial Controller
Echoplex Mode
Normal Mode
Serial Interface (RS-232B)
Grounds
Data Signals
Control Signals
Additional Control Signals
Electrical Signal Characteristics
Parallel Interface Controller
Parallel Controller I/O Bus

FIGURES
DELTA 1 USASCII CODE
3.0
DELTA 1 System Configuration
5.1 Input/Output Party Line Schematic
5.2 Party Line Data Input Timingl
5.3 Party Line Output Ti~in~
5.4 Party Line Timing
5.5 Sequential Priority Interrupt Schematic Diagram
6.1
6.2
7.1
7.2
8.0
9.0
5.1
7.1
Sequence/Response Diagram for Transmit
Data Commands from the Computer
Sequence/Response Diagram for Enter
Data Commands from the Computer
Sequence/Response Diagram for Transmit
Data Commands from the Computer
via a Parallel Interface
Sequence/Response Diagram for Enter
Data Commands from the Computer
via a Parallel Interface
Bits and DELTA 1 Control Codes
Keyboard
TABLES
Party Line I/O Connector
Parallel Interface Connector

1.0 INTRODUCTION
The DELTA 1 VIDEO DISPLAY TERMINAL is a complete stand
alone computer terminal for rapid entry, transmission,
and retrieval of digital information. It consists of
a controller, an alpha-numeric keyboard and a CRT dis-
play. A standard T.V. monitor is used for display of
an EIA-TV compatible signal. This makes possible the
operation of many T.V. monitors in a room or building
to display information to many users.
The DELTA 1 has a capacity of 960 characters, 40 on
each of 24 lines. A graphics mode provides display of
graphic information on a 128 by 64 matrix. Complete
capability for editing, formatting and transmitting
data is included to provide data manipulation hereto-
fore unavailable with a terminal in this price class.
Communications with the DELTA 1 is provided through an
EIA compatible serial communications interface. The
serial interface provides ASCII communications capa-
bility to make the ~ELTA 1 compatible with the Model
2701 communications controller of the IBM software.
A parallel interface is also available with DTL
electrical compatibility. Data is transferred through
the parallel interface using a REQUEST-ACKNOWLEDGE
control sequence providing compatibility with computer
input/output.
The most complete set of editing and format controls
are provided to simplify operator manipulation and
preparation of data. The character insert and delete
keys open or close a space on a line and the line
insert or delete keys open or close a line space. The
format control permits entering and protecting fixed
information while the operator enters variable infor-
mation. Transmission and clearing of the variable
information provides a high level of efficiency of
operation.
The selective blink feature permits any characters at
selected positions to blink to call the operator's
attention to the data.
Complete cursor control from the keyboard as well as
the computer is provided by cursor controls to position
the cursor anywhere on the screen. Variable trans-
mission and erase data commands provide the ability to
handle either the entire screen, a single line, or a
message.

options offered for the DELTA 1 include a light pen,
hard copy devices for printing what is on the screen,
closed circuit T.V. equipment for use in conjunction
with the DELTA 1, and various interfaces for communi-
cation and direct connection to other computers.
A. Options also include a 96 character set where
the 32 additional characters are either:
1. Lower case.
2. Line drawing characters.
3. ASCII control code graphic symbols.
(The use of any of these options requires that
the blink capability be deleted.)
1.1 SELECTIVE BLINK
The SELECTIVE BLINK feature permits the computer to
call attention to important information displayed on
the screen. Such information blinks on and off at
approximately a once per second rate. The operator's
eye is captured by the blinking and he can take appro-
priate action to acknowledge receipt of such information.
Blink will cause any field of characters to be in the
BLINK condition. When BLINK is established for a given
character position, any displayable characters stored
in that position will blink on and off on the screen.
Clearing the position to a space or changing the char-
acter will not stop the blink function. To stop a field
from blinking, the appropriate command must be entered
for each position for which the blink function should
be terminated. In this way, each position may be sep-
arately and independently programmed to blink or to
stop blinking as required.
BLINK is independent of the format function and will
be affected by whether a given position is FIXED or
VARIABLE data in the FORMAT MODE. Edit commands will
change the location of the blink field as well as data.
1.2 EDITING PACKAGE
The DELTA I has a complete set of data editing features.
Because an important characteristic of a CRT terminal
is the ability to receive data from a computer, mani-
pulate the data and then transmit back to the computer,
the edit features provided by the DELTA I are essential.
These are as follows:

A. Insert
The Insert Command causes a character space to be
opened up at the position of the Cursor and all
characters at that position and to the right are
moved over one place. The last character on the
line is discarded. The Cursor remains in its same
position and repeated operation of this key will
open up a multi-position space. The data to be
inserted can then be typed directly in without
affectinq subsequent lin~of data. This is used
to add a letter or a number in the middle of an-
other group of numbers or letters.
B. Insert Line
This command takes the entire line of data on which
the Curosr is located and moves it and all lower
lines down one line. The bottom line of data is
discarded. This opens up an entire line of data
for insertion into the body of the text.
C. Delete
This command causes the character at the position
of the Cursor to be replaced by the one immediately
on its right and all characters to the right of the
Cursor position to be moved to the left one posi-
tion. A space is brought into the last position
on the line. It is used to remove a word or char-
acter from a line without replacing it with some-
thing else. It differs from the normal typing
operation where any new characters typed over an
old one will simply repla,ce the old character with
the new one.
D. Delete Line
This command causes all characters on the same line
as the Cursor to be replaced by all the characters
on the next lower line. All lines below that are
moved up one line and spaces are brought into the
bottom line from a text without replacing it with
a different line.
E. Roll and Crawl
One of the important capabilities of the DELTA 1
Terminal through the edit functions is the ability
to ROLL data up and down by the use of the dele-
tion-Qr insertion command. New lines of data can
then be entered so that a continuously moving text

can appear on the screen of the terminal. The
same thing can be true for a single row of charac-
ters, CRAWLING from left to right or right to left.
In each case the appropriate characters or lines
to be entered can be displayed and moved up, down,
left or right.
1.3 REMOTE PROGRAMMING
The DELTA 1 display is capable of responding to a vari-
ety of commands to provide for remote operation of the
various function controls. These include all of the
format controls, the erase controls, and the transmit
control. In addition, the remote computer can cause the
Cursor to be set at any fixed position on the screen by
providing an absolute address to the terminal.
1.4 CURSOR CONTROLS
An extensive set of Cursor Controls is provided on the
DELTA 1. These are designed with two points of view;
For operator convenience, and to provide complete flex-
ibility to the computer programmer.
At the keyboard, there are 7 Cursor Commands~ These
include UP: DOWN, LEFT, and RIGHT. Also provided is the
HOME command which:mD-Ves the Cursor to the first posi-
tion of the first line, the RETURN command which moves
the Cursor to the first position of the following line,
and the BACKSPACE command which moves the Cursor back
one position.
All of the above Cursor Commands are programmable from
the computer which also has the capability for absolute'
positioning the Cursor any where on the screen with the
POSITION CURSOR COMMAND. The Cursor command, given with
a line and position number, will automatically move to
the position addressed. This provides the ultimate in
manipUlative capability from the computer.

2.0 SYSTEMS CONFIGURATION
The DELTA 1 display station consists of a number of mod-
ular components described in the following paragraphs:
2.1 DISPLAY CONTROL
The function of display control is to generate master
timing, integrate the refresh memory, generate the char-
acter font, and convert the digital character informa-
tion into a signal capable of being recognized by a
standard T.V. monitor. It also contains an EIA RS170
compatible sync generator which produces composite sync
and composite video signals. Optionally available is
a source of control signals necessary to permit the
Display Controller to be the source of synchronization
for any closed circuit T.V. facility.
2.2 DISPLAY
The technique used for generation and display of data
employs a scanned raster approach. The display is a
atandard CRT T.V. monitor mounted in a desk top housing.
The 12" screen will display 960 characters in 24 rows
of 40 characters each. Mounted on the side of the dis-
play station are three control knobs, for brightness,
contrast, and horizontal hold. At the users option,
other displays may be attached to the same controller
providing the opportunity to monitor the contents of
the screen in several different locations. These moni-
tors can be additional DELTA 12" display screens, or
large screen remote monitors can be used.
2.3 READ-ONLY MEMORY
The read-only memory is a permanent storage device. It
is programmed to contain a pattern of one's and zero's
which represent the shape of each of the standard 64
characters which can be displayed on the screen. Since
each character is made up of seven rows of five dots
each, the memory is broken up into 64 x 7 words of five
bits each.
2.4 MEMORY CONTROL
Memory control serves the purpose of addressing the
refresh memory and controlling the source and destina-
tion of the data. During that portion of the raster

scan in which the display is active, memory access is
controlled by a real time clock counter which defines
character position along the line and character line on
the page. During this time the data is transferred
from core memory to the Display Control.
If new characters are to be entered into the refresh
memory or if some other form of an edit is pending,
during the period of time in which the raster is re-
tracing., the memory address is the cursor address.
Data is either extracted from the memory or entered in-
to the memory during the retrace time,. as defined by
Edit Control.
2.5 REFRESH MEMORY
The refresh memory is a high speed, random access mag-
netic core storage. This unit contains 1024 eight-bit
words. In the DELTA 1, six bits are used for storage
of which of the 64 characters in the set is to be dis-
plqyed. The other two bits are used to store blink
and format information. In a 96 character-set display
or in a color terminal, one or the other of the remain-
ing two bits may be used for other information.
2.6 EDIT CONTROL
The function of Edit Control is to perform all editing
operations for the data received from either the com-
puter or the keyboard, and for sending all data to the
computer.
The basic edit functions include control of transmission
to and from a computer, clearing all or sections of
the display, entering data into the display, controlling
the cursor on the display, or manipulating data via the
insert, insert line, delete, or delete line commands.
2.7 SERIAL I/O CONTROL
The function of the Serial I/O Controller is to permit
the display system to communicate with a computer via
a communications line. The Serial I/O Controller
transmits and receives serial ASCII Coded data via a
telephone company supplied modem and converts it to edit,
transmit, or control commands for the display.
The Serial I/O Controller also performs the handshaking
operation required to establish communications.

2.8 PARALLEL I/O CONTROLLER
The function of the Parallel I/O Controller is to permit
direct communications between the display system and
other I/O devices. Such devices include small general
purpose computers, paper tape readers or punches, card
readers or punches, magnetic~ tape controllers, line
printers, and the keyboard.
The parallel I/O Controller contains a party line data
bus permitting the display controller and other peripheral
devices to share common information. To insure proper
direction of information flowing into or out of the data
lines, an interrupt structure is used. Thus, any device
requiring service will make a request which is stored in
the Parallel I/O Controller, and when the Controller
completes the processing associated with some other I/O
device control is transferred to the requesting peri-
pheral. During the time that this peripheral is using
the data bus, all other requests are stored and only
the peripheral presently using the I/O data bus can con-
trol the flow of data to or from the display controller.
2.9 KEYBOARD
The keyboard, as shown in figure 9, contains a stan-
dard typewriter keyboard, a display edit keyboard, and
a display control keyboard all in one package. The
standard typewriter keyboard permits entry of 26 charac-
ters, ten numbers, and 24 special symbols.
The edit keyboard permits relative motion control of the
cursor (up, down, left, and right), homes the cursor,
permits the establishment of formats and blink fields,
and permits the operator to enter or delete characters
or lines.
The control keyboard permits the operator to request
transmissions, to clear a message, display, line, to re-
set the display"to select the mode of operation, and
the mode of display, and permits a limited number of
special controls which will cause actions on external
I/O devices (up to ten can be supplied).

3.0 MODES OF OPERATION
There are three modes of operation for display of alpha-
numeric information. These are 1) conversation mode,
2) format mode, and 3) normal mode.
3.1 CONVERSATION MODE
The Conversation Mode is provided to facilitate conver-
sational dialogue between the computer and the DELTA 1
terminal. The purpose is to simplify operator actions
in communicating with the computer and to permit the
past conversation with the computer to be left displayed
on the screen.
After Activation of the Conversation Mode Key, the Mode
Light will go on. The address of the cursor is stored
in a register and the operator types his inquiry to the
computer. The last character of the message will be an
End Of Message (EOM) symbol. The terminal transmits
all information between the cursor locations stored ln
the register and the End Of Message symbol. The com-
puter begins its reply on the next line leaving displayed
the inquiry to the computer. When the computer has com-
pleted transmission of its message, it sends a Return and
returns control to the terminal. The terminal again stores
the address of the cursor in the address register and the
operator can type in the next inquiry.
In the Conversation Mode it is not necessary to constantly
reposition the cursor to the beginning of a message in
order to transmit. Furthermore, the entire dialogue
between computer and operator remains displayed on the
screen instead of being cleared after each communication.
The Conversation Mode is an important factor in the man-
machine interface problem by simplifying communications
with the computer. It, therefore, simplifies operator
intervention and training.
3.2 FORMAT MODE
The Format Mode is designed to simplify man-machine inter-
action. It is used when a pre-established format is
placed on the screen in the Normal Mode and requested
information (variable data) is typed in Format Mode.

An example of a format would be:
NAME:
ADDRESS:
CITY:
STATE:
ZIP:
S. S. #:
EMPLOYER:
The computer would transmit data in the Normal Mode to
establish such a format. Now, operating in the Format
Mode, the operator would be unable to erase the format
information. Operation of the tab control would move
the cursor to the start of the first variable data field.
The operator would then type (TAB) Richard M. Nixon
(TAB) 1600 Pennsylvania, Ave (TAB) WASHINGTON (TAB)
D.C. (TAB) 21111 (TAB) 333-333-3333 (TAB) U.S. GOVERN-
MENT (END OF MESSAGE).
The screen would then look like this:
NAME: RICHARD M. NIXON
ADDRESS:
1600 PENNSYLVANIA AVE
CITY: WASHINGTON STATE: D.C.
S. S. #: 333-333-3333
EMPLOYER: U.S. GOVERNMENT
ZIP: 21111
Now the operator is ready to transmit the variable data
to the computer. Since the computer established the
format in the first place, it knows what the format
information is. The transmit button is pushed and the
terminal sends only the variable data. Now, the clear
screen command is activated. This will clear the vari-
able data and bring the screen back to just the format
information, ready for a new entry.
When a delete or insert character editing function is
operated in the Format Mode, it only operates on the
field from the cursor to the end of the line or the end
of the variable data field, whichever shall occur first.
3.3 NORMAL MODE
The Normal Mode is the usual operating condition of the
DELTA I terminal. It provides unrestricted use of the
editing functions. Clear commands will operate on all
character positions and all data specified will be trans-
mitted in a send operation.
3.4 GRAPHIC MODE
An alternate mode of operation from that of ALPHA-NUMERIC
display is for GRAPHIC DATA DISPLAY. In this mode the

screen is divided up into 8192 spots on the face of the
screen. Each eight bit character in the refresh memory
of the terminal describes an on-off condition for any
one of a corresponding eight spots on the face of the
screen. The computer can then transmit data to the mem-
ory to provide a pattern of lit and unlit spots that
will draw lines, circles, and curves and generate char-
acters on the face of the screen. In this way graphic
data may be displayed and annotated using the DELTA 1.
No relationship exists between the positioning of the
alpha-numeric data on the screen and the graphic data.
3.4.1 LIGHT PEN TRACKING (OPTIONAL)
Light Pen Tracking permits use of the light pen to draw
lines and curves on the face of the screen. When the
light pen tracking control has been operated, the move-
ment of the pen across the face of the screen will cause
dots along the path of the pen to be turned on. This
pattern becomes stored in the refresh memory and can be
interrogated by the computer to provide input data.

4.0 T.V. COMPATIBILITY
The DELTA 1 Terminal is a T.V. compatible display. This
means the signal generated to drive the display portion
of the terminal is compatible with the television signal
generated in any closed circuit television system. This
opens up a broad avenue of applications for the DELTA 1
Terminal. Because of T.V. COMPATIBILITY, we are able
to make use of a standard solid state 12" T.V. set in
our terminal at an accompanying savings to the user.
This savings is in the form 6f initial cost as well as
maintainability because the operation of the circuits
within the display are identical to those of part of a
standard commercial television set.
4.1 USE WITH CCTV EQUIPMENT
The T.V. compatible signal drives a standard 525 line
T.V. monitor or modified T.V. set. The display asso-
ciated with each keyboard can be monitored remotely
through a closed circuit television system. A single
television distribution amplifier can be used to drive
several remote monitors in different locations.
A standard commercially available Video Tape Recorder
may be used to record the data being displayed for later
retrieval and display. The output of a closed circuit
television camera can be combined with the signal from
the DELTA 1 terminal to superimpose computer generated
information onto a T.V. signal for display or recording.
This is useful in many applications where existing
closed circuit television systems can be combined with
the output data generated by a computer. Graphic data
such as pictures from slides or art work can be scanned
by a T.V. camera and annotated by the signal from DELTA 1
terminal.
4.2 RASTER SCAN
Characters are created on the screen in the TV raster
mode by blanking and unblankinq of the TV beam as it
moves laterally across the screen. The beam moves across
the screen 525 times to create a normal TV picture. Suc-
cessive sweeps skip every other line creating two fields
of scan of 262 and 263 lines equally spaced up and down
the screen. This is known as an interlace. In the
DELTA 1 terminal, the information on each field is re-
freshed identically so that in effect we have 262 lines
on the screen rather than 525. Since each is written
30 times per second, an equivalent refresh rate of 60
per second assures a flicker free display.

The display characters are formed in the middle 212 T.V.
lines which made up of seven lines per character and two
lines between rows on each of 24 rows of characters.
The cursor is written on the 8th line of each character
row and the 9th line is always used as a separation to
to row below.
It takes approximately 52 microseconds for the beam to
sweep from one side of the screen to the other and approx-
imately 12 microseconds for it to return back to the left
hand side. During the 52 microsecond period as it sweeps
the screen, the beam is turned on and off to generate one
line of the character. However, the first 5 microseconds
of the sweep are not used in order to assure a placement
of the characters in the center of the screen and reduce
maintenance problems from drift of the characters to the
left or right of the visible area of the screen.
4.3 SYNC SIGNAL AND COMPOSITE VIDEO
The output signal from the Delta 1 generator to the dis-
play station and to remote monitors is a standard EIA
Video signal as per specification RS 170 of the Electri-
cal Industries Association. This specification provides
the exact timing and characteristics of the synchroni-
zation signal for the TV receiver and the composite video
signal.
The sync signal must have a pulse at the beginning of
each line of video data to cause the beam to return from
the right hand side of the screen to the left hand side.
When the proper number of these pulse signals have been
generated at 60 microsecond intervals, a horizontal
synchronization sequence is generated. These provide the
triggering necessary for the TV receiver to cause return
of the beam from the bottom of the screen on the right
to the top of the screen on the left. The receiver is now
ready to receive a new vertical sync pulse and video data
for the next field of display.
Standard synchronization signals are available as outputs
from the generator to be used to trigger T.V. cameras
and other closed circuit television equipment used in
conjunction with the DELTA 1 terminal. Sync signal is
mixed with the digital data to provide a composite video
signal. This is the type of signal normally received
from the output of a television camera and required by dis-
tribution amplifiers and monitors in a closed circuit TV

system. The compatibility with EIA standard RS 170 assures
operation with closed circuit or broadcast TV equipment.
When operating in conjunction with TV equipment, it is
necessary to provide the synchronization signals to the
equipment from the Delta 1 display in order to provide
for compatibility in operation.

5.0 INPUT-OUTPUT TRANSFER
All data transferred to and from the DELTA I passes
through the party line input/output bus. This consists
~f eight bi-directional data lines and a series of con-
trol lines. These control lines provide for transfer
of data through the data register. Data is transferred
to and from the memory via the data register.
A priority input/output structure is provided through
the party line I/O to permit various devices to gain
exclusive access.
The single input/output port provided by the party line
I/O is used by the serial communications interface, the
parallel communications interface as well as other I/O
devices. All data exchanged with the external world is
passed to the memory through the party line I/O.
5.1 PARTY LINE I/O BUS
The DELTA 1 controller employs a "Party Line" I/O bus to
communicate with peripheral equipment.
The party line at the last device must be terminated
with a resistor whose value is the characteristic
impedence of the signal line. This is done to minimize
reflections. Since the data lines are bilateral, i.e.
they can be driven from either end, a termination is
required at each end. The control lines, which are
unilateral, are required to be terminated only at the
receiving end of the line. Figure 5.1 shows the circuit
schematics of both types lines. Signal lines should be
twisted pairs. Peripheral design should try to minimize
the length of the line. While the controller can
operate at long distances an effort should be make to
keep the party line cable under 12 feet long.
5.2 COMMANDS
All commands described in the following paragraphs
may be initiated from a remote source. To initiate
them the controller expects the fiist input word to be
the code for the command and the COMEN signal to be true
during the transfer. If the command is a XMIT the
XMITEN signal must also be true during the transfer.