NEC PD750008 - Manual (Page 306)

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µPD750008 USER'S MANUAL
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).
BRCB !caddr
Function: For the µPD750008 PC
12-0
<– PC
12
+ caddr
11-0
caddr = n000H-nFFFH
n = PC
12
= 0, 1
Branches to the address specified by the program counter whose low-order 12 bits
(PC
11-0
) have been replaced with the 12-bit immediate data caddr (A
11-0
).
Since the program counter of the µPD750004 consists of 11 bits, this instruction enables a branch to any
location in the program memory space.
In the µPD750006 and µPD750008, PC
12
cannot be changed, so no branch occurs beyond the block.
Similarly, in the µPD75P0016, PC
12
and PC
13
cannot be changed, so no branch occurs beyond the block.
Caution The BRCB !caddr instruction usually causes a branch within the block containing the
instruction. However, if the first byte is located at address 0FFEH or 0FFFH, a branch to
block 1 instead of block 0 occurs.
If the BRCB !caddr instruction is located at a or b in the figure above, a branch to block 1 instead of block
0 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).
a
b
7 0
Program memory
0FFEH
0FFFH
1000H
Block 0
Block 1