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CHAPTER 14
INSTRUCTION SET
SUBNB A, r
(Subtract Register from A. Skip if No Borrow)
<1> Operation code
:
0
1
1
0
0
0
0
1
0
1
1
0
R2 R1 R0
<2> Number of bytes :
2
<3> Number of states :
8 (8)
<4> Function
A ← A–r; Skip if no borrow.
:
0
Subtracts the contents of the register r (V, A, B, C, D, E, H, L) specified by R2R1R0 (0 to 7) from the contents
of the accumulator, and stores the result in the accumulator. Skips if no borrow is generated as a result of
the subtraction.
<5> Flags affected
:
Z, SK, HC, L1 ← 0, L0 ← 0, CY
<6> Example
:
SUBNB A, D; A ← A–D
A skip is performed if no borrow is generated as a result of the subtraction.
SUBNB r, A
(Subtract A from Register. Skip if No Borrow)
<1> Operation code
:
<2> Number of bytes :
0
1
1
0
0
0
0
0
0
1
1
0
R2 R1 R0
2
<3> Number of states :
8 (8)
<4> Function
r ← r–A; Skip if no borrow.
:
0
Subtracts the contents of the accumulator from the contents of the register r (V, A, B, C, D, E, H, L) specified
by R2R1R0 (0 to 7), and stores the result in the specified register. Skips if no borrow is generated as a result
of the subtraction.
<5> Flags affected
:
Z, SK, HC, L1 ← 0, L0 ← 0, CY
<6> Example
:
To subtract A from the HL register pair.
256
SUBNB
L, A; L ← L–A, SKIP IF NO BORROW.
SUI
H, I; H ← H–1