Tektronix 4956 User manual

Tektronix , Inc.
P.O.
Box
500
Beaverton ,
Oregon
97077
070-2210-00
TEKTRONIXⓇ
4956
GRAPHICS
TABLET
OPERATOR'S MANUAL
First Printing FEB 1977

AN
WARRANTY
This Tektronix product is warranted against defective materials
and workmanship , under normal use , for a period of one year
from date of initial shipment . Tektronix will repair or replace , at its
option ,
those products
determined
to be
defective
within
the
warranty
period and
returned ,
freight prepaid ,
to a
Tektronix
service center .
In
addition , in those
areas where
Tektronix
has service
centers
available for this product , on - site warranty repair is provided at no
charge
during the first
ninety ( 90
) days from
date of initial
shipment .
y
There is no implied warranty for fitness of purpose .
Copyright ©
1977 by
Tektronix , Inc.
Beaverton ,
Oregon .
Printed
in the United States of America . All rights reserved . Contents of
this publication may not be reproduced in any form without
permission of
Tektronix
,
Inc.
U.S.A. and foreign TEKTRONIX products are covered by U.S. and
foreign patents and / or patents pending .
TEKTRONIX is a registered trademark of Tektronix , Inc.
a

Section 1
Section 2
Section
3
4956
Graphics Tablet
CONTENTS
General Information
Some
Words
About
Terminology
Introduction to
the Graphics
Tablet
Graphics Tablet Components
Graphics Tablet Operation
Introduction
Generation of Coordinates
Digitizing
Modes
Time
and
Distance Filters
Origin
and
Coordinates
Transfer of Coordinates
Status
Byte
Back
Panel
Switches
Input
Procedure
Example Program
Tablet
Controller
Interrupt
Optimizing
Data
Transfer
Plot
50 :
Graphics
Tablet
Support
Software
Introduction
User
-
Definable Keys and
Graphic
Functions
Internal Data
Structure
Tape
Data
Structure
Operating
Notes
Initializing
Plot
50 :
Graphics
Tablet
Support
Software
Programs
for
the
Writing Pen
(
Menu
Items 1-5
)
Pen
Display Only
Pen
Display
and
Save
Pen Save Only
Pen
Display
and Store
Pen
Store
Only
Tape
Editing Programs
(
Menu Items
6 and 7 )
Data Tape Edit
Data
Tape
Merge
@
8
.
.
.
Page
1-1
1-1
1-2
2-1
2-1
2-1
2-2
2-2
2-5
2-5
2-7
2-8
2-9
2-9
2-10
3-1
3-1
3-2
3-4
3-6
3-7
3-8
3-8
3-10
3-14
3-17
3-19
3-22
3-22
3-30

ii
Section 4
Section 5
Section 6
Appendix
A
Appendix
B
Appendix C
Appendix D
Index
CONTENTS (
cont
)
Programs
for
the
Four
Button
Cursor
( Menu Items 8 through 12 )
Cursor
Display
Only
Cursor
Display and
Save
Cursor Save Only
Cursor
Display
and Store
Cursor
Store
Only
Tablet Maintenance
Biasing
the
Tablet
Checking
the
Tablet and
Tablet
Controller
Cleaning
the Tablet
Surface
Installation
Introduction
Installation
Steps
Setting
Coordinate
Units
AC
Power
Requirements
AC
Power Cord and
Grounding
Requirements
Line Voltage Selection
Fuses
Repacking
Information
Specifications
Internal
Switch
Settings
Plot 50 : Support Software Variables
Supplemental
Programs
Change
Information
Error
Messages
REV
. A ,
MAR
.
1978
.
.
.
.
.
Page
3-35
3-36
3-38
3-42
3-44
3-47
4-1
4-3
4-3
5-1
5-1
5-3
5-6
5-6
5-7
5-7
5-7
4956
Graphics
Tablet

Fig
.
No.
1-1
1-2
1-3
1-4
1-5
2-1
2-2
3-1
4-1
4-2
5-1
5-2
5-3
CONTENTS (
cont
)
4956
Graphics Tablet
ILLUSTRATIONS
Standard
4956
Graphics
Tablet
Graphics
Tablet
configuration in
4051
Graphic
System
Standard
Tablet
default
coordinate
plane
Tablet
Controller
Front
Panel
Tablet
Controller
Back
Panel
Different
Coordinate
Planes
Back
Panel
Switch
with
factory
settings
Four
Button
Cursor
Error
caused
by
uneven
Tablet
bias
Biasing
the
Tablet
Tablet
connection
GPIB
cable
connection
Internal
switch
locations
.
TABLES
Table
2-1A
Normal
Status
Byte
Values
2-1B
Special Four Button Cursor Status Byte Values
Back
Panel
Switch
Bank
2-2
3-1
Graphic Functions Represented in D values
3-2
5-1
5-2
6-1
Cursor Button and User - Definable Key Functions .
Range
of
Digitizing Units
4956
Operating
Voltages
4956 Operating Voltage Specification
REV . A , MAR . 1978
.
.
.
.
.
Page
Frontispiece
1-2
1-3
1-5
1-6
2-3
2-7
3-35
4-1
4-2
5-1
5-2
5-3
Page
2-6
2-6
2-7
3-4
3-36
5-4
5-6
6-1
iii

iv
TEKTRONIX
TEKTRONDE
KAN
VER
Fig
. 1-1 .
Standard 4956
Graphics Tablet
.
2210-01
4956
Graphics
Tablet
●

I
Section 1
GENERAL
INFORMATION
SOME
WORDS
ABOUT
TERMINOLOGY
The
TEKTRONIX 4956
Graphics
Tablet
is
designed
to
be used with a
TEKTRONIX 4050 - Series
Graphic System . The term Graphics Tablet is used in this manual to refer to the 4956 Graphics
Tablet
which includes the 20
" X 20 "
Tablet
as a
standard
component , and
Option
33
which
substitutes
a
36 " X 48 "
Tablet . The term
Graphic System is used to
reference
a
4050 - Series
Graphic System , which includes the 4051 Graphic System .
INTRODUCTION TO THE
GRAPHICS
TABLET
The Graphics Tablet inputs graphic data on command to the Graphic System through the
GPIB
interface . By using
BASIC
instructions
, the
Graphic
System
can
display
or store
the
graphic data
using
either
existing software or user -
designed
special
purpose
programs
. The
graphic material can be in many forms , such as handwriting , schematics , or freehand design .
With the feature of direct graphic input , the Graphics Tablet greatly enhances the graphic
capabilities of the
Graphic
System .
This section describes the three basic components of the Graphics Tablet : the Tablet , the
Writing Pen , and the Tablet Controller . Although the Tablet surfaces may vary in size , the
operating procedure is the same . The Writing Pen and Tablet are used just like pen and paper .
The function of the Tablet Controller is to convert the position of the Writing Pen on the Tablet
surface to the corresponding ASCII character coordinate pair . This process is called digitizing .
The coordinates and a status byte are sent to the Graphic System when an appropriate INPUT
instruction is executed . The operating procedure is explained in Section 2 of this manual .
4956
Graphics Tablet
Section 3 describes the Plot 50 : Graphics Tablet Support Software Tape which provides BASIC
programs that use Tablet coordinates and status information to display and / or store the
graphic data in memory or on magnetic tape . These programs are a convenient way to use the
Graphics Tablet . The programs make use of user - definable keys and five special programs are
included for use with the optional four - button Cursor . In addition , two programs edit data files
created
by the
software
programs .
1-1

GENERAL
INFORMATION
1-2
GRAPHICS
TABLET
COMPONENTS
The
configuration of
the
Graphics
Tablet
components in
the
Graphic
System is
shown
in
Fig .
1-2 .
The
following
paragraphs
describe
each
component
and
how
coordinates
are
digitized .
MANO MAN A
van me and they say
4051
77
TABLET
CONTROLLER
O
ma
WRITING
PEN
Fig
. 1-2 .
Graphics
Tablet
configuration in
4051
Graphic System
.
TABLET
2210-02
TABLET
The
Tablet and the
Writing Pen
are
used just like
pen and
paper
. The
Tablet has
a flat
surface on
which
paper
(
transparencies
,
etc. ) is
placed
.
The Writing
Pen
is
used
to
trace or
draw on
the
paper .
The
position of
the
Writing Pen
on the
Tablet
surface
is digitized
and
ASCII
character
coordinates are
produced
.
The
coordinates lie
on an X - Y
coordinate
plane
and
the
values are
relative to the
origin
. By
default , the
origin
is at the
lower
left
corner of the
Tablet
. X
coordinates
are
measured
horizontally
from the
origin and
Y
coordinates are
measured
vertically
as
shown in Fig
. 1-3 .
Identifiable points are .005 " apart .
4956
Graphics
Tablet

TEKTRONIX 4956
Y
Axis
Origin
( , 4000 )
4956 Graphics Tablet
( 0,0 )
Fig . 1-3 .
Standard
Tablet
default
coordinate
plane
.
GENERAL INFORMATION
@
(
4000 ,
4000 ) .
(
, 4000 )
To digitize coordinates , a grid of magnetized ( biased ) wires under the Tablet surface is used .
The
horizontal set of
wires is for the X
axis and
the
vertical set is for the Y
axis .
Pulses are
propagated along these wires and detected by a sensitive coil in the tip of the Writing Pen . The
time
between
transmission of a
pulse and its
detection
represents
a
coordinate
of
a point . For
each coordinate , two pulses are sequentially sent from opposite ends of the coordinates axis
wires , producing two values . The Tablet Controller then performs calculations on the two
values to produce highly accurate results .
X
Axis
2210-03
1-3

GENERAL INFORMATION
1-4
Only
a
certain
portion of the
Tablet
surface is used
as the
digitizing area
. This area
is not
marked on the
surface
since
it may move
when the Tablet
is biased
. (
Biasing
is
explained in
Section
4. )
However , the
minimum
size
of the
digitizing
area
is
standard
for
each of the
Tablet
sizes .
For example
,
the physical
size of
the standard
4956
Tablet
is 27.75
" X
27.75 "
while
the
digitizing
area
is
20 " X 20
" . The
digitizing
area may be
located by
moving
the
Writing Pen
on the
Tablet
surface near
the
metal
frame while watching
the
PROX
indicator on the
front panel of
the
Tablet Controller
. The
PROX
indicator
illuminates
when the
Writing
Pen is
in the
valid data
area
and
extinguishes
when
the
Pen leaves
the area .
WRITING
PEN
The
Writing
Pen is
used to
draw
on the
Tablet
surface
.
The tip of
the
Writing
Pen contains
a
sensitive
pick -
up
coil .
Whenever
the
tip
of
the Pen
is
within
5/32
inch of
the Tablet
surface ,
the
pick - up
coil detects
the
Tablet (
the
Pen is in
Proximity
) .
The
coil detects
the
change
in the
magnetic
field
caused
by
the pulse
on
the
Tablet
wires .
Coordinates
are
calculated
when
the
Pen detects the pulse .
Pressing
the tip of
the Writing
Pen against
the Tablet
surface
moves
the Pen's
filler
slightly
into
the
Pen .
This action
activates
a switch
,
located
within
the Writing
Pen
.
The Z
Axis
indicator
illuminates
when the
switch is
activated
.
This switch
can be
used
to
separate
coordinates
obtained
when
moving
the
Pen in
the
Proximity
area of
the Tablet
from
those
obtained
when
the
Pen is
actually
on
the Tablet
surface
as
explained in
Section
2
.
The
Writing
Pen's
inkless
filler
can be
replaced
by the
blue ballpoint
filler
so that
marks
can
be
seen .
If
accuracy is
desired
,
when
tracing
a
drawing ,
for
example ,
the
Writing
Pen
can
be
replaced by
an
optional
one -
button or
four -
button
Cursor
. In
the
Cursor ,
the switch
is
activated
by
pressing
the large
button on
top of
the cursor
.
TABLET
CONTROLLER
The
Tablet Controller
contains
the
power supply
and the
necessary
circuitry
to digitize
coordinates .
Upon
command of
the
Graphic
System ,
the
Tablet Controller
conveys
coordinate
and
status
information through
the
General
Purpose
Interface
Bus
(
GPIB ) .
Power is
applied
to
the
Graphic
Tablet
by
moving
the power
switch
on
the back
panel of
the Tablet
Controller
to
the
ON
position .
The front
panel
of
the
Tablet
Controller ,
shown
in
Fig .
1-4
,
contains
the
following
buttons
and
indicators .
NOTE
Before
applying
power to
the Graphics
Tablet ,
see the
installation
instructions
in
Section 5 .
4956
Graphics
Tablet