2845 Commands And Command Operation - IBM 2265 Manual

(See causes of No Response under "Summary of Sequences
and Responses" and 2701 line timeouts under "Timing
Considerations". )
The 2845 response to an addressing sequence depends
on the nature of the 2845 command and conditions at the
2845 and the selected device. The various 2845 responses
to an addressing sequence are shown in Figures 6 through
13 and described under "Summary of Sequence and
Responses" .
Table 3. Display Control Address Assignments
Display
Control Hexadecimal USASCII-8 Address Code
Number Representation
8
7 6 5 4 3 2 1
1 40 0 1 0 0 0 0 0 0
2 41
0 1 0 0 0 0 0
1
3 42 0 1 0 0 0 0 1 0
4 43 0 1 0 0 0 0 1 1
5
44
0 1 0 0 0 1 0 0
6 45 0 1 0 0 0 1 0 1
7 46 0 1 0 0 0 1 1 0
8 47 0 1 0 0 0 1 1 1
9 48 0 1 0 0 1 0 0 0
10
49
0 1 0 0 1 0 0 1
11 4A
0 1 0 0 1 0 1 0
12 4B
0 1 0 0 1 0 1
1
13 4C
0 1 0 0
1 1 0 0
14 40
0 1 0 0 1 1 0
1
15 4E
0 1
0 0 1 1 1 0
16 4F 0 1 0 0 1 1 1 1
Note: Any invalid or unasssigned display control address code may
be transmitted as part of an addressing sequence, however it will
not be acknowledged by the 2845. The 2845 will remain in con-
trol mode.
2845 COMMANDS AND COMMAND OPERATION
The remote display system equipped with the Line Address-
ing and Printer Adapter Features can execute eight com-
mands. These commands, their USASCII-8 code structure
and hexadecimal representation, and the feature required
(if any) to enable their execution, are listed in Table 5.
Table 5. 2265/2845 Commands
USASCII-8 Code Structure
2845 Command 8 7 6 5 4 3 2
1
Specific Poll-2265 0 1 0 0 0 0
0 0
Specific Poll-Printer 0 1 0 0 0 0 0 0
General PolI* 0 1 0 0 0 0 0 0
Read Addressed Full OS Buffer 0 1 0 1 0 0 0 0
Write Addressed DS 1 0 1 0 0 0 0 0
Write Printer
.1
0 1 0 0 0 0 0
Write DS Line Address 1 0 1 1 0 0 0 0
Erase/Write Addressed DS 1 1 1 0 0 0 0 0
The operation of each 2845 command is controlled and
monitored by exchanges (between the I/O channel and the
2845 Display Control) of a single USASCII communication
control character or a sequence of characters of which one
(or more) is a USASCII communication control character.
These exchanges are called "sequences" and "responses".
The sequences and responses that occur during an opera-
tion depend upon the command, conditions at the display
system, and the program. The sequence and response dia-
grams (Figures 6 through 13) illustrate possible sequences
and responses that may occur during each operation. Each
figure is divided vertically by a broken line. Sequences and
responses to the left of the line represent those that may be
transmitted by the I/O channel to the 2845. Sequences and
responses to the right of the line represent those that may
be transmitted by the 2845 to the I/O channel. The heavy
line indicates the sequences and responses that occur most
frequently during an operation; the lighter lines indicate
other possible sequences and responses.
Table 4. Remote Device Address Assignments
Display
Control Printer Hex Display Station Hex
Number Address Byte
Rep Address Byte Rep
8 7 654 3 2 1 8 7 6 5 4 3 2 1
1
o
1 00000 0 40 0 1
o
1
o
0 0 0
50
2
o
1 00000 1
41
o
1 0 1 000 1 51
3
o
1
o
0 0 0 1 0 42
o
1 0 1 001 0
52
4
0 1 000011 43 0 101 001 1
53
5
o
1 000 1
o
0 44
o
1
o
1
o
1 0 0 54
6
o
1 000 1
o
1 45
o
1 0 1
o
1
o
1 55
7 0 1 000 1 1 0
46 0 1 0 1
o
1 1 0 56
8 0 1 00011 1 47
o
1
o
1
o
1 1 1 57
9
o
1 001 000 48
o
1
o
1 1 000 58
10
o
1 001 001 49
o
1
o
1 1 001
59
11
0 1 001 010 4A
o
1
o
1 1 010
5A
12"
01 001 011
4B
o
1
o
1 1
o
1 1 5B
13
o
1 001 100 4C
0 1
o
1 1 100 5C
14
o
1 001 1
o
1 4D
o
1
o
1 1 1
o
1
50
15
o
1 001 1 1 0 4E
0 1
o
1 1 1 1 0
5E
16
o
1 001 1 1 1 4F
o
1
o
1 1 1 1 1 5F
Hexadecimal
Representation
Feature Required
40
40
Printer Adapter Feature
40
50
AO
AO
Printer Adapter Feature
BO Line Addressing Feature
EO
*The General Poll is identified by the third character of the addressing sequence (Device Address). An all ones code for this character (FF)
and the indicated Command Code signifies the General Poll.
Principles of Operation 29