NEC PD750008 - Manual (Page 307)

287
CHAPTER 11 INSTRUCTION SET
BR PCDE
Function: For the µPD750008 PC
12-0
<– PC
12-8
+ DE
PC
7- 4
<– D, PC
3-0
<– E
Branches to the address specified by the program counter whose low-order 8 bits (PC
7-0
) have been
replaced with the contents of the DE register pair. The high-order bits of the program counter are not affected.
Caution The BR PCDE instruction usually causes a branch within the page containing the instruction.
However, if the first byte of the instruction code is located at address xxFEH or xxFFH,
a branch to the next page instead of that page occurs.
If the BR PCDE instruction is located at a or b in the figure above, a branch to page 3 instead of page 2
occurs, jumping to the low-order 8 bits of the address specified by the contents of the DE register pair.
BR PCXA
Function: For the µPD750008 PC
12-0
<– PC
12-8
+ XA
PC
7- 4
<– X, PC
3-0
<– A
Branches to the address specified by the program counter whose low-order 8 bits (PC
7-0
) have been
replaced with the contents of the XA register pair. The high-order bits of the program counter are not affected.
Caution As with the BR PCDE instruction, if the first byte is located at address xxFEH or xxFFH,
a branch to the next page instead of the page containing the instruction occurs.
Remark "Function" in this section is applicable to the µPD750008 whose program counter consists of
13 bits (addr = 0000H to 1FFFH).
However, this is also applicable to the µPD750004 whose program counter consists of 12
bits (addr = 0000H to 0FFFH), the µPD750006 whose program counter consists of 13 bits
(addr = 0000H to 17FFH), and the µPD75P0016 whose program counter consists of 14 bits
(addr = 0000H to 3FFFH).
7 0
Program memory
02FEH
02FFH
0300H
Page 2
Page 3
a
b