NEC PD17062 - Manual (Page 40)

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PD17062
6. GENERAL-PURPOSE REGISTER (GR)
The general-purpose register is allocated in data memory space, and is used to perform direct operations
on the data in data memory and to transfer data to and from data memory.
6.1 STRUCTURE OF THE GENERAL-PURPOSE REGISTER
Fig. 6-1 shows the structure of the general-purpose register.
As shown in Fig. 6-1, 16 words (16 words
×
4 bits) having the same row address in data memory space can
be used as the general-purpose register.
The row address to be used as the general-purpose register can be specified using the general-purpose
register pointer of the system register. The general-purpose register consists of seven bits. However, the
high-order four bits are fixed to 0 so, within the data memory space, only row addresses 0H to 7H of BANK0
can be used as the general-purpose register.
See Section 8.6.
6.2 FUNCTION OF THE GENERAL-PURPOSE REGISTER
The general-purpose register can be used to perform an operation or to transfer data between itself and
data memory with the execution of a single instruction. The general-purpose register is allocated in data
memory space. This enables an operation or transfer to be performed between data memory locations by
the execution of a single instruction.
Like other data memory, the general-purpose register can be controlled using a data memory manipulation
instruction.