Operation Codes; Timing Considerations; Modes Of Communication - Beehive International B150 Series Operator's Manual

memory following this sequence to blink.
The ESC-b sequence causes the keyboard to be
enabled (data can be entered from the keyboard.
The ESC-c sequence causes the keyboard to be
disabled (data cannot be entered from the key
board).
WARNING - Only thecomputer can remove ^e
disabled state after the keyboard is locked, unless
the Control, Shift and Home /Clear keys are d^
pressed together. This command will do a Rcocl
FUNCTION, but all display data is lost because
this is still a Clear sequence.
The cursor can be sent to a specific location
on command of the operator. Use the keys
ESC-F followed by two characters (see Table
3-2) that represents the line and column co
ordinates for the character location. If oper
ating in FORMAT MODE and the cursor is
placed in a protected area of the display as
a result of this command, the cursor will
scan right and will stop when it finds the
first unprotected location.
The ESC-0 sequence produces a page type
block send out the Auxiliary Port.
3A OPERATION CODES
The B15G series code structure consists of 32 ASCII
control codes, 95 ASCII alphanumerics, and 96 es-
caoe sequence codes. Operation codes perform the
necessary functions in response to commands gene
rated by control or escape code sequences rather
than a single key command. These functioYis may
be generated from the keyboard or received at the
I/O pert. Addendum I gives an ASCII chart which
lists the code, describes their function, and lists the
code sequence with the octal code.
3.5 TIMING CONSIDERATIONS
Certain functions require longer intervals than one
character time at high transmission rates to com
plete the operation. Longer intervals are provided
by inserting filler (null) codes into the data block.
The number of characters required to fill these inter
vals for various operations and various baud rates
is given in Table 3-1. Although any character may
be used, the NULL character (000 octal) is sug
gested, since this code will be completely ignored.
3-4
Table 3-1 TIMING FILLER NULL CODES
BAUD RATE
FUNCTION 19200 9600 7200 4800
3600
CLEAR
5
nulls
3
nulls
1
nulls
0 0
EOS FROM HOME
5
nulls
3
nulls
1
nulls
0
0
TAB
2
nulls
0
0
0
0
FORMAT ON (ESC-
10
nulls
8
nulls
6
nulls
4
nulls
2
nulls
I/O BAUD SWITCH #
14 13 12
11
10
3.6 MODES OF COMMUNICATION
The B150 series terminals are capable of operating
Off-Line (Local) or On-Lina In the Local mode,
all communication with external devices is cut off
and data generated at the keyboard is only seen
locally by the terminal itself. Three operational
modes of communication are provide when the
unit is On-Line: Full Duplex (conversational),
Half Duplex (conversational), and Block. Full
duplex operation allows data to be transmitted
with the terminal's receiver input enabled for im
mediate computer reply of the transmitted data
(echoplexed) to verify proper receipt of the data.
Half duplex data transfer is generally used for mes
sages or sending messages character-by-character
where echoplex is not available. Keyboard data
entered while the terminal is operating in half duplex
is entered into memory and displayed and does not
require the echoplex process from the CPU to veri
fy accuracy of the message. In Block mode, data
generated at the keyboard is not sent out the main
I/O port butis sent directly to the screen. This
mode allows the operator the option of composing
the message on the screen, verifying its accuracy,
and sending the entire message on command. The
transmission of the message is initiated by depress-
in the SEND key. The data can be sent a lineat a
time with the simultaneous actuation of the SEND
and the SHIFT keys. While transmitting data in
eitherthe Line or Page modes, the keyboard is dis-