TSC80251 TEMIC [TEMIC Semiconductors], TSC80251 Datasheet - Page 17

• Manufacturer Part Number: TSC80251
• Manufacturer: TEMIC [TEMIC Semiconductors]

Rev. C – May 7, 1999
Address Spaces
TSC80251 microcontrollers have three address spaces: a memory space, a Special Function Register (SFR) space and
a register file. This chapter describes these address spaces as they apply to all TSC80251 microcontrollers. It also
discusses the compatibility of the C251 Architecture and the C51 Architecture in terms of their address spaces.
3.1. C251 Architecture Address Spaces
Figure 3.1. shows the three address spaces: i.e. memory space, SFR space and register file for TSC80251
microcontrollers. The address spaces are depicted as being 8–byte wide with addresses increasing from left to right
and from bottom to top (See Figure 3.1. ).
It is convenient to view the unsegmented, 16–Mbyte memory space as consisting of 256 64–Kbyte regions, numbered
00: to FF:.
Note :
The memory space in the C251 Architecture is unsegmented. The 64– Kbyte “region” 00:, 01:, ..., FF: are introduced only as a convenience for
discussions. Addressing in the C251 Architecture is linear; there are no segment registers.
TSC80251 microcontrollers can have up to 64–Kbytes of on–chip code memory in region FF:. On–chip data RAM
begins at location 00:0000h. The first 32 bytes (00:0000h-00:001Fh) provide storage for a part of the register file.The
sizes of the on–chip code memory and on–chip RAM depend on the particular device.
The register file has its own address space (See Figure 3.1. ). The 64 locations in the register file are numbered
decimally from 0 to 63. Locations 0-7 represent one of four, switchable register banks, each having 8 registers. The
32 bytes required for these banks occupy locations 00:0000h-00:001Fh in the memory space. Register file locations
8-63 do not appear in the memory space and are new hardware resources of the C251 Architecture.
The SFR space can accommodate up to 512 8–bit Special Function Registers with addresses S:000h-S:1FFh. Some
of these locations may be unimplemented in a particular device. In the C251 Architecture, the prefix “S:” is used with
SFR addresses to distinguish them from the memory space addresses 00:0000h-00:01FFh.
Figure 3.1. Address Spaces for TSC80251 Microcontrollers
00:0000h
Memory Address Space
16 Mbytes
FF:FFFFh
00:0007h
S:000h
00h
Register File space
64 bytes
SFR Space
512 bytes
TSC80251
S:1FFh
S:007h
3Fh
07h
3.1