NEC PD17062 Manuale Utente

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Data memory can be used to perform, with one instruction, a four-bit operation, comparison, decision, or

transfer of the data in data memory and immediate data (arbitrary data) by executing one of the data memory

manipulation instructions listed in Table 5-1.

If the general-purpose register is used, a four-bit operation, comparison, or transfer between data memory

and the general-purpose register can be performed by a single instruction.

Examples are given below.  See Chapters 6 and 7 for details.

; 

#

MOV  35H, #0001B ; Transfer (write) immediate data 0001B to data

; memory address 35H in the currently selected bank.

; 

$

ADD  76H, #0001B

; Add immediate data 0001B to the contents of

; data memory address 76H in the currently selected ;bank.

In instructions 

# and $, the currently selected bank is specified in the bank register of the

system register.  For an explanation of the bank register, see Chapter 8.

In 

$, the instruction is for addition to the contents of data memory address 76H.  Address

76H is part of the system register.  Because the system register always exists regardless of

the bank, the ADD instruction eventually adds 0001B to the contents of address 76H of the

system register, regardless of the bank.

Remark   For explanation of how to code instructions, see Section 5.3.1.

Assume that the general-purpose register is allocated to row address 1H of BANK0.

; 

#

ADD  7H, 36H

; Add the contents of data memory address 36H in the

; currently selected bank to the contents of the

; general-purpose register location having column address

; 7H, or address 17H of BANK0.

; 

$

LD     7H, 36H

; Transfer the contents of data memory address 36H to

; the general-purpose register location having column

; address 7H.

; In this instruction, the general-purpose register

; location is address 17H of BANK0.

The system register, data buffer, general-purpose register, and port registers can be manipulated in the

same way as data memory by using the data memory manipulation instructions.

Sections 5.2.1 to 5.2.4 describe the functions of these registers.