Keylock Feature; Operating Procedures; Communication Modes; Transmit Mode (T) - IBM 3742 Reference Manual

Keylock Feature
This feature controls the use of the communication mode.
In the locked position communication mode cannot be
used and in the unlocked position it can be used. The 3741
terminal can also be locked in a communications mode per-
mitting communication with a remote terminal. However,
once the 3741 is removed from COMM, the key must be
used to permit re-entry. Also, if the first or second disk is
removed, communications mode is discontinued.
OPERATING PROCEDURES
An overview of the general operating paths is shown in
Figure 26. Procedures pertaining to modem keys may vary
depending on the modem type installed.
Figure 27 illustrates the status indicators displayed on the
CRT display status line during BSCA operation.
COMMUNICATION MODES
Figure 28 summarizes the effect of disk label status on
data sets in the various BSCA modes. The following
further explains the individual BSCA modes.
Transmit Mode (T)
The transmit mode will be used to transmit data from one
disk or two disks (if the second disk feature is installed) to
a remote location. After loading the disks to be trans-
mitted, an operator can place the 3741 terminal in a trans-
mit mode by pressing FUNCT SEL upper, COMM, and T_
A T will then be displayed on the status line of the CRT
display to indicate the transmit mode.
When the 3741 is in transmit mode, it can be connected to
the telephone line through modem, and subsequently trans-
mit data from the disk to the remote location.
The procedure in the previous paragraph was for transmit-
ting one or two disks in their entirety. If the operator de-
sires to start transmission from any position on the first
disk, he can position the disk to any record of any data
set with normal key entry operations, and subsequently
start the transmission of data from that point.
If transmission occurs with no errors, a TT is displayed on
the display's status line to indicate a completed trans-
mission. If a disk error, invalid data set label, or a trans-
parency error occurs, TI will be displayed in the display's
status line to indicate an incompleted transmission. If the
mode indicator is TT or TI, the 3741 will not automatically
answer a telephone call. If the mode indicator remains T
(as it would if a line check, remote abort, or message
aborted error occurred), the 3741 will answer a telephone
call and will retransmit the data beginning at the same
place as the original call.
If the customer intends to use any transmit mode, he must
not write as data a % character in position 1 of sector 01001
since this unique condition is reserved for initiating a BSCA
diagnostics procedure.
Communications 51