User’s Manual
C166S V1 SubSystem
Central Processing Unit
User’s Manual
3-55
V 1.6, 2001-08
3.6.2.1
Addressing via Data Page Pointer
The 4 non-bit-addressable DPP registers select up to 4 different data pages. The lower
10 bits of each DPP register select one of the 1024 possible 16-KByte data pages, while
the upper 6 bits are reserved for the future use. The DPP registers provide access to the
entire memory space in 16-KByte pages.
The DPP registers are used implicitly whenever data accesses to any memory location
are made via indirect or direct long 16-bit addressing modes (except for override
accesses via EXTended instructions and PEC data transfers).
Data paging is performed by concatenating the lower 14 bits of an indirect or direct long
16-bit address with the contents of the DDP register selected by the upper 2 bits of the
16-bit address. The contents of the selected DPP register specify one of the 1024
possible data pages. This data page base address together with the 14-bit page offset
forms the physical 24-bit address.
After reset, the DPP registers select data pages 3-0 within segment 0. If the user does
not want to use any data paging, no further action is required.
0
9
DPP
0
15 14
16-Bit Data Address
0
23 15 14
00’0000
H
01’0000
H
FE’0000
H
FF’0000
H
Memory
Figure 3-9
Addressing via the Data Page Pointer
DPP3 - 11
DPP2 - 10
DPP1 - 01
DPP0 - 00
selects DPP
Segment
Segment offset
Page
Page offset
0
254
x
255
1
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: ......