DS80CH11 Datasheet, PDF (25/88 Pages) Dallas Semiconductor – System Energy Manager

DS80CH11
4.2.2 Dual Data Pointer
A second data pointer register (DPTR 1) is incorporated
into the SEM in addition to the standard one in the 8051.
This feature allows faster execution of many operations
involving data memory access, such as block moves.
Operation of the dual data pointer function is fully docu-
mented in the Dallas High Speed Micro User’s Guide.
4.3 EXTERNAL MEMORY INTERFACE
Interface techniques for interfacing external memory as
program or data storage to the SEM via Ports 0 and 2
are described in the Dallas High Speed Micro User’s
Guide.
4.4 DIRECT (SCRATCHPAD) RAM ACCESS
The SEM incorporates a full 256 bytes of direct RAM.
This RAM is accessed in a manner identical to that of a
standard 80C52 compatible device. A full description of
this memory along with the instructions that access it is
contained in the Dallas High Speed Micro User’s Guide.
4.5 SPECIAL FUNCTION REGISTERS
Special Function Registers (SFRs) control most special
features of the SEM. This allows the SEM to have many
new features but use the same instruction set as the
8051. When writing software to use a new feature, an
equate statement defines the SFR to an assembler or
compiler. This is the only change needed to access the
new function. The SEM duplicates the SFRs contained
in the standard 80C52. Table 4–2 is a summary of the
values loaded into the SEM’s SFR’s on reset. Table 4–3
is a summary of all of the SFR’s and the control bits they
contain.
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