Burroughs -B9351/B9353 Input and Display Systems Technical Manual Sec. I
Page
3
Introduction and Operation
or group
of
sections associated with a separate monitor and
keyboard. Each section or group
of
sections associated with
a particular keyboard
is
loaded by that keyboard or by an
incoming
message
addressed to the associated monitor. The
content
of
each section or group
of
sections
of
the memory
is
displayed on the associated monitor at a flicker-free
re-
fresh rate.
All
or part
of
the display content
of
a section or
group
of
sections
of
the memory
is
transmitted
as
an out-
going message upon command from the associated key-
board.
MEMORY
For each monitor-keyboard connected to the Input
Display System, six memory bytes are reserved for internal
functions and the remainder
of
the memory assigned to the
screen
is
available for display data. The number
of
bytes
available for display data on a monitor
is
dependent upon
the number
of
sections
of
memory assigned to the monitor
as
follows:
Number
of
Total Number
of
Number
of
Display
Sections
of
Memory Memory Bytes Data Memory Bytes
Assigned to Monitor Assigned to Monitor Assigned to Monitor
1
256
250
2 512 506
3
768
762
4
1024 1018
The display data consists
of
both graphics and format
effectors.
The first display data memory byte corresponds to
the upper left screen position.
If
this character is a graphic,
the next memory byte corresponds to the next screen posi-
tion on the line. Each graphic character in memory assigns
the next memory byte
to
the next screen position across
each line and automatically from the end
of
one line to the
beginning
of
the next line. A format effector in memory
assigns
the next memory byte to a screen position depen-
dent upon the format effector. For example, the format
effector character
NL
(new line)
assigns
the next memory
byte to the first position
of
the next line; therefore, the
.screen positions after the NL screen position do not have an
associated byte in memory. These screen positions are
referred to
as
unassigned positions. Two memory bytes
are
required for eight
of
the graphic characters,
$,%,&;'S.,
x,] ,t,
and--.
One memory byte
is
required for each screen for
the end-of-screen position. This byte
is
one
of
the six
mentioned above.
DISPLAY FORMAT
The memory data content
is
displayed on a 17-inch
CRT. Table
1-2
lists the CRT display characteristics. The
tube
is
masked to correspond to the horizontal and vertical
extremities
of
the 80-character by 25-line format, which
Printed in U.S. America 10-12-70
yields a 12-inch horizontal by 9-inch vertical, rectangular
display presentation.
Corresponding to each
of
the graphic codes stored in
memory' the appropriate graphic character
is
generated by
using up to
12
straight-line strokes to form the character. A
cursor presentation
is
also provided.
It
appears at the char-
acter position where the next keyboard or Input/Output
operation
is
to take place. The character
is
formed on the
screen
as
a set
of
horizontal
brackets,=,
that surround the
character position, such that the character
to
be edited
re-
mains viewable. Chart
1-1
shows the font
of
the Input
Dis-
play graphic character set.
CHARACTER SET
AND
CODE
Burroughs Input Display System uses a modified
limited subset
of
the USASCII, USASCII X3.4. Figures
1-2
and
1-3
designate the characters to each seven-bit character
code for receive and transmit respectively.
With the exception
of
five
character substitutions,
namely the
characters~.~'
x, ¢
and~in
lieu
of
the char-
acters !, ',
I,
/\ and - , respectively, the figures agree with
the proposed USASCII. These figures differ only in the
inclusion
of
certain characters.
Undesignated Codes
Received character codes undesignated in Figure
1-2
are undefined in the Input Display System. The character
codes undesignated in Figure
1-3
are not generated by the
Input Display System.
OPERATION
Operation may
be
considered
to
consist
of
four
phases: Composition, Send, Wait, and Receive. The modes
are independent for each keyboard.
COMPOSITION PHASE
In the composition phase, the operator may compose
a message by using the keyboard shown diagrammatically in
Figure
1-4.
The operator has complete freedom to edit and
compose information anywhere on the screen (except with
forms mode option).
The composition phase
is
ended by pressing the
SEND or PRINT keys, either
of
which evoke the Send
phase.During composition phase, the KEYBOARD
LOCK
indicator
is
OFF. Depressing the KEYBOARD key reverts
the terminal to the composition phase. The keyboard con-
sists
of
graphic, cursor movement, and control keys. Certain
of
the keys work in conjunction with the SHIFT key.
A graphic key causes the character depicted by the
keytop designation to appear at the position
of
the cursor.
If
the cursor position already displays a graphic character, it
is
replaced by the new character. The cursor moves forward
For Form 1044187
I
