User’s Manual
C166S V1 SubSystem
Central Processing Unit
User’s Manual
3-15
V 1.6, 2001-08
The Instruction Pointer IP
This register determines the 16-bit intra-segment address of the currently fetched
instruction within the code segment selected by the CSP register. The IP register is not
mapped into the C166S’s address space, and thus it is not directly accessible by the
programmer. The IP can be modified indirectly by return instructions via the stack. The
IP register is updated implicitly by the C166S for branch instructions and after instruction
fetch operations.
The Code Segment Pointer CSP
This non-bit-addressable register selects the code segment being used at run-time to
access instructions. The lower 8 bits of register CSP select one of up 256 segments of
64 KBytes each, while the higher 8 bits are reserved for future use.
IP
Instruction Pointer
(----
H
,--
H
)
Reset value: 0000
H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
IP
0
(r)(w)h
r
Field
Bits
Type Description
IP
[15:1]
rwh
Specifies the intra-segment offset from which the
current instruction is to be fetched; IP refers to the
current segment <SEGNR>.
0
[0]
r
IP is always word-aligned
CSP
Code Segment Pointer
SFR(FE08
H
,04
H
)
Reset value: 000x
1)
H
1)
The reset value of the bitfield segnr[1:0] is product-specific. With an alternate boot mode feature, the code
execution can be started at different segments after reset.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
SEGNR
r
r
r
r
r
r
r
r
r(w)h
Field
Bits
Type Description
SEGNR
[7:0]
rwh
Specifies the code segment from which the current
instruction is to be fetched
Содержание C166S V1 SubSystem
Страница 10: ...User s Manual C166S V1 SubSystem User s Manual I 6 V 1 6 2001 08...
Страница 16: ...User s Manual C166S V1 SubSystem Introduction User s Manual 1 6 V 1 6 2001 08...
Страница 126: ...User s Manual C166S V1 SubSystem Central Processing Unit User s Manual 3 96 V 1 6 2001 08...
Страница 178: ...User s Manual C166S V1 SubSystem Memory Organization User s Manual 4 52 V 1 6 2001 08...
Страница 206: ...User s Manual C166S V1 SubSystem Instruction Set User s Manual 5 28 V 1 6 2001 08...
Страница 306: ...User s Manual C166S V1 SubSystem Detailed Instruction Set User s Manual 6 100 V 1 6 2001 08...
Страница 362: ...User s Manual C166S V1 SubSystem The External Bus Interface User s Manual 8 40 V 1 6 2001 08...
Страница 452: ...User s Manual C166S V1 SubSystem General Purpose Timer Unit User s Manual 12 44 V 1 6 2001 08...
Страница 454: ...User s Manual C166S V1 SubSystem Instruction Index User s Manual 13 2 V 1 6 2001 08...
Страница 459: ......