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SEQUENTIAL
MODIFICATION
OF USASCII TO
EXTENDED USASCII
(Cont'd)
~SEQUENTIAL
MODIFICATION OF
IBM 1050 CODE
Reference Information
2.
Under control of systems classification, the CCM extends this line
code by deleting the parity bit (27) and expanding the character by
shifting the 2 5 and 2
6
positions so that they become the 2 5 and 27
positions respectively., See Example
(2)
below.
3.
The original 2 6 bit is then duplicated in the newly created 2
5
position
making the character an eight-bit code. See Example
(3)
below.
8
4.
The CCM then adds the correct parity in the 9th level (2 ) before
the character is passed to the standard interface of the multiplexor
channel. See Example
(4)
below.
(Example is the Letter
D)
(1)
2
7
2
6
2
5 24
2
3 22 21
2
0
P
1
0
0
0
1
0
0
(2)
/5
1
2
6
2
X
~4 ~3
+2 +1
~o
2 2 2 2 2
1
0
0
0
1
0
0
7
6
5
4
2
3
2
1
0
2
2
2
2
2
2
2
(3)
1
0
1
0
0
1
0
0
I
•
(4)
2
8 27
2
6
2
5 24
2
3 22 21
2
0
P 1
0
1
0
0
1
0
0
•
The IBM 1050 code received from the communication line will be con-
figured as a
7
-level code with parity in the
2 6
bit (check bit). This parity
bit is shifted by the transmitting terminal so it is the first bit received from
the line. The 27 bit is added by the CCM to reflect the shift status estab-
lished by the previous shift character. Upshift for 1050 is 1 and downshift
is
o.
Parity is added by the CCM in the 2 8 bit position.
(Example is the letter D)
B
A
C
8
4
2
1 - IBM bit designations
2
0 21
2
6 22
2
3 24
5
2
1
1
0
0
1
0
0
Received from the line as:
B
A
8
4
2
1
C
2
0 21 22
2
3
4
2
5
6
2
2
1
1
0
1
0
0
0
3-3
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