16F84A Microchip Technology, 16F84A Datasheet - Page 6

• Manufacturer Part Number: 16F84A
• Description: 18-pin Enhanced Flash/EEPROM 8-Bit Microcontroller
• Manufacturer: Microchip Technology

PIC16F84A
2.2
The data memory is partitioned into two areas. The first
is the Special Function Registers (SFR) area, while the
second is the General Purpose Registers (GPR) area.
The SFRs control the operation of the device.
Portions of data memory are banked. This is for both
the SFR area and the GPR area. The GPR area is
banked to allow greater than 116 bytes of general
purpose RAM. The banked areas of the SFR are for the
registers that control the peripheral functions. Banking
requires the use of control bits for bank selection.
These control bits are located in the STATUS Register.
Figure 2-1 shows the data memory map organization.
Instructions MOVWF and MOVF can move values from
the W register to any location in the register file (“F”),
and vice-versa.
The entire data memory can be accessed either
directly using the absolute address of each register file
or indirectly through the File Select Register (FSR)
(Section 2.4). Indirect addressing uses the present
value of the RP0 bit for access into the banked areas of
data memory.
Data memory is partitioned into two banks which
contain the general purpose registers and the special
function registers. Bank 0 is selected by clearing the
RP0 bit (STATUS<5>). Setting the RP0 bit selects Bank
1. Each Bank extends up to 7Fh (128 bytes). The first
twelve locations of each Bank are reserved for the
Special Function Registers. The remainder are Gen-
eral Purpose Registers implemented as static RAM.
DS35007A-page 6
Data Memory Organization
Preliminary
2.2.1
Each General Purpose Register (GPR) is 8 bits wide
and is accessed either directly or indirectly through the
FSR (Section 2.4).
The GPR addresses in bank 1 are mapped to
addresses in bank 0. As an example, addressing loca-
tion 0Ch or 8Ch will access the same GPR.
FIGURE 2-1:
File Address
Note 1: Not a physical register.
Unimplemented data memory location; read as '0'.
0Ch
0Ah
0Bh
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
4Fh
50h
7Fh
GENERAL PURPOSE REGISTER FILE
Indirect addr.
Registers
EEDATA
PCLATH
INTCON
STATUS
Purpose
General
(SRAM)
PORTB
EEADR
PORTA
Bank 0
TMR0
FSR
PCL
68
REGISTER FILE MAP -
PIC16F84A
(1)
1998 Microchip Technology Inc.
Indirect addr.
OPTION_REG
EECON2
EECON1
PCLATH
STATUS
INTCON
(accesses)
TRISA
TRISB
in Bank 0
Bank 1
Mapped
FSR
PCL
(1)
(1)
File Address
80h
81h
82h
83h
84h
85h
86h
87h
88h
89h
8Ah
8Bh
8Ch
CFh
D0h
FFh