IBM 2790, Руководство пользователя, Страница: 41 / 88

2715 to System/360
System/360 to 2715
Type
Hex Code Type
Hex Code
Transaction ID
L
i­
b
s \
o o
1053 Printer Data 'FA'
Positive Response CPU Request 'CA' 2740 Terminal Data 'FB'
Negative Response CPU Request 'CB' Control Requests 'Cl '-'C ?”
Response Invalid CPU Request 'CC' ' D l ' D 9 '
Positive Response 2715 Request 'DA'
sO L
U
I
C
N
L
U
Negative Response 2715 Request
'DB'
'EA'-'EC'
Response Invalid 2715 Request 'D C
User Defined
'F0'—'F91
Unsolicited 2715 Response 'FD'
• Figure 24. Transaction Control Byte
Note that in the last two cases the user program still has
access to the 2740 or 1053 output within the normal output
limitations. Thus the user may reroute this traffic under
control of the user program if he wishes.
When rerouting transactions, the user should be careful
not to violate the following. The time field must be restored
to valid EBCDIC numeric characters before rerouting mes­
sages to the 2740. The idle character must not be sent to
the 1053 Printer (it is an invalid character for the printer).
The idle character should be sent to the 2740 printer if the
tab carriage control character is embedded in the text. If
a new-line character is embedded in the text, the 2715
inserts the required trailing idle characters.
Read-Deferred-Data Mode
Read-deferred-data mode is set or reset by a control trans­
action from the System/360. When read-deferred-data mode
is set and the 2715 has no priority data, deferred data is
sent to the System/360 as soon as a full block of data is on
the disk.
If the 2715 receives a ‘stop 2790 input’ control transac­
tion prior to receiving ‘set read deferred data mode’, the
response to ‘set read deferred data mode’ is held up until
all data is sent to the CPU. When all data has been sent,
the 2715 resets read-deferred-data mode and sends a posi­
tive response to the CPU. The ‘reinitialize disk’ control
transaction will not be accepted by the 2715 until both
‘stop 2790 input’ and ‘set read deferred data mode’ have
been executed and the positive response to ‘set read defer­
red data mode’ have been executed and the positive response
to ‘set read deferred data mode’ has been sent.
Data Format
Data Entry
A data entry consists of a single block of data entered by an
operator at an area station, data entry unit, remote badge
reader, or other input device. See “Area Stations” and
“Data Entry Units” for definition by device type
The Transaction
A transaction may consist of one to thirteen data entries
from a 2796, or from one to sixteen data entries from a 2791
or 2795, for a maximum of 247 data bytes per transaction.
An assembled transaction consisting of single or multiple data
entries has an eight-byte header prefixed to the first data
entry. Thus, the maximum transaction length is 255 bytes.
IBM 2715 Transmission Control Unit 41