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The dual-access DSU may be tested in an identical manner with two additional test positions:
L*
L&
L¢
18
17
16
15
14
13
12
11
10
9
8
7
Same as single access
SAMPLE CODING TO ADDRESS a DSU
Below is given a sample coding for positioning the arm:
NIS
7
BZE
*-1
CSR
0
BEV
*-1
BMI
*-
2
LDB
1st Word (Command)
STB
3
LDD
2nd and 3rd Word (Command)
STD
4
single access
LOCKOUT INDICATOR
The other processor has set
lockout bit
Test and Branch - the other processor
has issued a test-and-branch instruction
SEL
(Arm starts seek for Position. DSU goes ready when in position. Now issue
Read or Write.)
Below is given a sample coding for a read or write operation:
NIS
7
BZE
*-1
CSR
0
BEV
*-1
BMI
*-
2
LDB
1st Word (C0mmand) Read/Write
STB
3
LDD
2nd and 3rd Word (Command) Read/Write
STD
4
SEL
(To Execute Read/Write.)
@&tr&~~trCl ~@------------
V-42
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