NEC PD17062 - Manual (Page 66)

66
µ
PD17062
8.6 GENERAL-PURPOSE REGISTER POINTER (RP)
The general-purpose register pointer points to the bank and row address of the general-purpose register.
However, since RPH of the
µ
PD17062 is fixed at 0, only RPL (3 bits) can be specified. This means that 0
to 7 can be specified as a register pointer. Hence, in the
µ
PD17062, the row address of the general-purpose
register can be specified anywhere within BANK0.
8.7 PROGRAM STATUS WORD (PSWORD)
The program status word consists of a flag that indicates the result of operation by the ALU in the CPU and
a 5-bit flag that modifies the ALU function. PSWORD has a binary coded decimal (BCD) flag, compare (CMP)
flag, carry (CY) flag, zero (Z) flag, and index enable (IXE) flag. Fig. 8-6 shows the functions of these flags.
Fig. 8-6 Configuration of PSWORD
b 0 b 3 b 2 b 1 b 0
BCD CMP CY Z IXE
When the arithmetic operation result is other than 0, this flag
is reset. The set condition differs according to the contents of
the CMP flag.
7EH 7FH
Index
enable
flag
When this flag is set, index modification is enabled.
Zero flag (1) When CMP = 0
The flag is set when the arithmetic operation result is 0.
(2) When CMP = 1
The flag is set when the result of the arithmetic operation
executed at Z = 1 is 0.
Carry flag
The carry flag is set when a carry occurs during the execution
of an addition instruction or when a borrow occurs during the
execution of a subtraction instruction. This flag is reset when
neither carry nor borrow occurs.
This flag is set when the least significant bit of the general-
purpose register is 1, in which the RORC instruction is executed.
The flag is reset when the bit is 0.
Compare
flag
When this flag is set, the arithmetic operation result is not
stored into data memory.
The CMP flag is reset automatically when the SKT or SKF
instruction is executed.
BCD flag
When this flag is set, all arithmetic operations are executed in
decimal. When this flag is not set, all arithmetic operations are
executed in binary.