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LOAD A-REGISTER (LDA) EXECUTION CYCLE.
transferring information from M to A (Figure 8):
This instruction performs the function of
1.
The operand address in L is transferred to the memory address lines for accessing
the memory.
2.
The contents of M are transferred to the arithmetic unit.
3.
The contents of M are transferred through the arithmetic unit to Z.
4.
The contents of M are transferred from Z to A, thus loading A with the contents of M.
5.
Simultaneously with steps 2, 3, and 4, the contents of M are being regenerated by the
memory drivers.
6.
The branch flip-flops store the plus, zero, and even conditions of the contents of
memory.
COllTJIOU.ll
Io
COllTROIJ.,!R
I
7
- - - - - - - - - - - - - - - - - - - - - - - - -
-
-
I
A
REGISTER
18
B
REGISTER
18
Q
COUNTER
14
p
COUNTER
4
15
L
REGISTER
AD>IESS
REGISTER
1
MEMORY;:
UNIT
I
N
REGISTER
I
I
I
1S
I
I
_J
HE!l)RY
ADDRESS
-1
I
LINES
15
I
MAGll!TIC
CORE
MEll>llY
REGISTER
INSERT
SWITCHES
18
I
MEMORY
I
DRIVIRS
18
I
I
18
I
5
I
---'
Figure 8. Detailed Block Diagram DATANET-30
Load A (LDA)
I-18
BRANCH FLIP ·FLOPS
FLUS
Zl!RO
Z
DRIVERS
18
3
ARITllHETIC
UNIT
2
Y
REGISTER
18
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