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WORD
TYPE
0
0
STORAGE
CONTROL
2
3
00= READ CONTROL
01 =READ AUX OR
PROGRAM
10 =STORE CNTL
11 =STORE AUX
OR PROGRAM
BIT 11 DETERMINES IF THE
AUXILIARY STORAGE AREA
OR THE PROGRAM STORAGE
AREA IS ACCESSED FOR BIT
2, 3 DECODES OF 01 and 11.
THIS IS ONLY TRUE WHEN
INDIRECTLY ADDRESSING.
WHEN NO ACCESS TO STORAGE
IS DESIGNATED BY THE MODI-
FIER CONTROL FIELD. BITS
2 and 3 INDICATE THE UPDATE
VALUE.
BITS
VALUE
2,3
00
0
01
+OR -1
10
+OR -2
11
+OR -2
DATA REGISTER ADDRESS
4
5
6
7
THIS FIELD MAY ADDRESS LOCAL
STORAGE FOR A BYTE OR HALFWORD.
BYTE SELECTION OF LOCAL STORAGE
IS LIMITED TO THE ODD ADDRESSES.
HALFWORD SELECTION IS LIMITED TO
EVEN ADDRESS
EXTERNAL FACILITY ADDRESSING
IS ALWAYS DONE IN BYTE MODE.
THEREFORE ONLY THE EXTERNALS
WITH ODD ADDRESSES CAN BE
ACCESSED.
LOCAL
STORAGE DECODES
0000-
uo
0001 -
Ul
0010-
VO
0011 -
Vl
.0100-
GO
0101 -
Gl
0110-
DO
0111 -
Dl
1000-
10
1001 -
11
1010-
TO
1011 -
Tl
1100-
PO
1101 -
P1
1110 -
HO
1111 -
H1
ALL EVEN ADDRESSES CAN BE
USED AS ADDRESS REGISTERS IN
THE FIELD DESIGNATED BY CON-
TROL WORD BITS 8, 9,
1'0, and
11.
ADDRESS REGISTER OR K FIELD
8
9
10
11
FOR INDIRECT ADDRESSING
THE ADDRESS REGISTER SELECTED
BY THIS FIELD IS A HALFWORD
LOCAL STORAGE REGISTER
BIT 11 DOES NOT ENTER INTO
THE ADDRESSING OF THE LOCAL
STORAGE REGISTER. BUT DOES
INDICATE THE FOLLOWING
BIT
BITS
MEANING
11
2,3
0
01 READ AUXILIARY
1
01 READ PROGRAM
0
11 STORE AUXILIARY
1
11 STORE PROGRAM
FOR DIRECT ADDRESSING
THIS FIELD CONTAINS BIT CODES
THAT FORCE THE ADDRESS REG-
ISTER M1 TO SPECIFIC VALUES
THESE VALUES ARE -
BITS
FORCED M1
8,9, 10, 11
VALUES
0000
88
0001
BA
0010
8C
0011
8E
0100
98
0101
9A
0110
9C
0111
9E
1000
A8
1001
AA
1010
AC
1011
AE
1100
B8
1101
BA
1110
BC
1111
BE
12
000
001
010
011
100
101
110
111
MODIFIER CONTROL
13
14
NO UPDATE
DIRECT ADDRESSING
NO ACCESS, PLUS
UPDATE.
NO ACCESS, MINUS
UPDATE.
LOCAL STORAGE
DATE REG, ACCESS,
PLUS UPDATE
LOCAL STORAGE DATE
REG, ACCESS, MINUS
UPDATE
EXTERNAL DATA REG.
ACCESS, PLUS UPDATE
EXTERNAL DATA REG,
ACCESS, MINUS UPDATE
FOR K ADDRESSABLE
AUX
MO = 00000000
CTRL
Mo=yooo11
DEPENDENT
ON STORAGE SIZE
WORD
TYPE
0
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