XC2200 Derivatives
System Units (Vol. 1 of 2)
Central Processing Unit (CPU)
User’s Manual
4-74
V2.1, 2008-08
CPUSV2_X, V2.2
4.10
Constant Registers
All bits of these bit-addressable registers are fixed to 0 or 1 by hardware. These registers
can be read only. Register ZEROS/ONES can be used as a register-addressable
constant of all zeros or all ones, for example for bit manipulation or mask generation. The
constant registers can be accessed via any instruction capable of addressing an SFR.
ZEROS
Zeros Register
SFR (FF1C
H
/8E
H
)
Reset Value: 0000
H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
Field
Bits
Type Description
0
[15:0]
r
Constant Zero Bit
ONES
Ones Register
SFR (FF1E
H
/8F
H
)
Reset Value: FFFF
H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
r
Field
Bits
Type Description
1
[15:0]
r
Constant One Bit