PIC17C7XX Datasheet, PDF (63/328 Pages) Microchip Technology – High-Performance 8-Bit CMOS EPROM Microcontrollers with 10-bit A/D

8.4 Operation with External Memory
Interface
When the table reads/writes are accessing external
memory (via the external system interface bus), the
table latch for the table reads is different from the table
latch for the table writes (see Figure 8-9).
This means that you cannot do a TABLRD instruction,
and use the values that were loaded into the table
latches for a TABLWT instruction. Any table write
sequence should use both the TLWT and then the
TABLWT instructions.
PIC17C7XX
FIGURE 8-9: ACCESSING EXTERNAL MEMORY WITH TABLRD AND TABLWT INSTRUCTIONS
TABLPTR
TABLATH (for Table Reads)
TABLRD
TABLATH (for Table Writes) _TABLWT
Program Memory
(In External Memory Space)
© 1998 Microchip Technology Inc.
DS30289A-page 63