NEC PD754144 - Manual (Page 281)

CHAPTER 11 INSTRUCTION SET
281 User’s Manual U10676EJ3V0UM
BR PCDE
Function: PC 11-0
← PC 11-8 + DE
PC 7-4
← D, PC 3-0
← E
Branches to an address specified by the lower 8 bits of the program counter (PC
7-0
) replaced with the contents
of register pair DE. The higher bits of the program counter are not affected.
Caution
The BR PCDE instruction usually branches execution to the page where the instruction exists. If the first byte of
the op code is at address
××FE or ××FFH, however, execution does not branch in that page, but to the next page.
7 0
02FFH
0300H
Page 3
Page 2
Program memory
02FEH
a
b
For example, if the BR PCDE instruction is at position a or b in the above figure, execution branches to the lower
8-bit address specified by the contents of register pair DE in page 3, not in page 2.
BR PCXA
Function: PC 11-0
← PC 11-8 + XA
PC 7-4
← X, PC 3-0
← A
Branches to an address specified by the lower 8 bits of the program counter (PC
7-0
) replaced with the contents
of register pair XA. The higher bits of the program counter are not affected.
Caution
This instruction branches execution to the next page, not to the same page, if the first byte of the op code is at
address ××FEH or ××FFH, in the same manner as the BR PCDE instruction.