Ram Data Memory; Str�Ct�Re; Special P�Rpose Data Memory - Holtek HT46R003B Manual

HT46R003B
Cost-Effective A/D 8-bit OTP MCU

RAM Data Memory

The Data Memory is a volatile area of 8-bit wide RAM internal memory and is the location where
temporary information is stored.
Structure
Divided into two sections, the first of these is an area of RAM where special function registers are
located. These registers have fixed locations and are necessary for correct operation of the device.
Many of these registers can be read from and written to directly under program control, however,
some remain protected from user manipulation. The second area of Data Memory is reserved for
general purpose use. All locations within this area are read and write accessible under program
control.
The two sections of Data Memory, the Special Purpose and General Purpose Data Memory are
located at consecutive locations. All are implemented in RAM and are 8 bits wide but the length of
each memory section is dictated by the type of microcontroller chosen. The start address of the Data
Memory for the device is the address "00H".
All microcontroller programs require an area of read/write memory where temporary data can be
stored and retrieved for use later. It is this area of RAM memory that is known as General Purpose
Data Memory. This area of Data Memory is fully accessible by the user program for both reading
and writing operations. By using the "SET [m].i" and "CLR [m].i" instructions individual bits can
be set or reset under program control giving the user a large range of flexibility for bit manipulation
in the Data Memory.
Note: Most of the Data Memory bits can be directly manipulated using the "SET [m].i" and "CLR
[m].i" with the exception of a few dedicated bits. The Data Memory can also be accessed
via the memory pointer registers.
Special Purpose Data Memory
This area of Data Memory is where registers, necessary for the correct operation of the
microcontroller, are stored. Most of the registers are both readable and writeable but some are
protected and are readable only, the details of which are located under the relevant Special Function
Register section. Note that for locations that are unused, any read instruction to these addresses will
return the value "00H".
Rev. 1.00
0 0 H
I A R 0
0 1 H
M P 0
0 2 H
S p e c i a l
I A R 1
P u r p o s e
0 3 H
R e g i s t e r s
M P 1
3 F H
4 0 H
6 4 b y t e s
G e n e r a l
P u r p o s e
R e g i s t e r s
7 F H
Data Memory Structure
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