PIC18C242 MICROCHIP [Microchip Technology], PIC18C242 Datasheet - Page 53

• Manufacturer Part Number: PIC18C242
• Description: High-Performance Microcontrollers with 10-Bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

5.0
Enhanced devices have two memory spaces: the pro-
gram memory space and the data memory space. The
program memory space is 16 bits wide, while the data
memory space is 8 bits wide. Table Reads and Table
Writes have been provided to move data between
these two memory spaces through an 8 bit register
(TABLAT).
The operations that allow the processor to move data
between the data and program memory spaces are:
• Table Read (TBLRD)
• Table Write (TBLWT)
FIGURE 5-1:
FIGURE 5-2:
7/99 Microchip Technology Inc.
Note 1: Table Pointer points to a byte in
Note 1: Table Pointer points to a byte in
Instruction: TBLRD*
Instruction: TBLWT*
TABLE READS/TABLE WRITES
program memory
program memory
TBLPTRU
TBLPTRU
TABLE READ OPERATION
TABLE WRITE OPERATION
TABLE POINTER
TABLE POINTER
TBLPTRH
TBLPTRH
Program Memory
(TBLPTR)
(1)
(1)
Program Memory
(TBLPTR)
TBLPTRL
TBLPTRL
Preliminary
PROGRAM MEMORY
PROGRAM MEMORY
Table Read operations retrieve data from program
memory and place it into the Data memory space.
Figure 5-1 shows the operation of a Table Read with
program and data memory.
Table Write operations store data from the data mem-
ory space into program memory. Figure 5-2 shows the
operation of a Table Write with program and data mem-
ory.
Table operations work with byte entities. A table block
containing data is not required to be word aligned, so a
table block can start and end at any byte address. If a
table write is being used to write an executable program
to program memory, program instructions will need to
be word aligned.
TABLE LATCH (8-bit)
TABLE LATCH (8-bit)
PIC18CXX2
TABLAT
TABLAT
DS39026B-page 53