CHAPTER 3. FEATURES OF ARCHITECTURE AND MEMORY MAP
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3.2 MEMORY-MAPPED I/O
The
µ
PD75402A adopts memory-mapped I/O to map such peripheral hardware as the input/output port, serial
interface at addresses F80H to FFFH in the data memory space shown in Table 3-1. As a result, there is no special
instruction to control the peripheral hardware; the peripheral hardware is controlled wholly by memory manipu-
lation instructions (some hardware control mnemonics are available to make the program easy to understand).
Table 3-3 shows the addressing modes available when operating the peripheral hardware.
Table 3-3 Applicable Addressing Modes at Peripheral Hardware Operation
Applicable Addressing Mode
Specify the bit to be manipulated by the direct
addressing mem.bit.
Specify the bit to be manipulated by the direct
addressing fmem.bit.
Specify the address to be manipulated by the direct
addressing mem.
Specify the address to be manipulated by the direct
addressing mem. Mem is an even address, however.
Applicable Hardware
All the hardware capable of bit
manipulation
IE×××, IRQ×××, PORTn.×
All the hardware capable of 4-bit
manipulation.
All the hardware capable of 8-bit
manipulation.
Bit manipulation
4-bit manipulation
8-bit manipulation
Table 3-4 summarizes the
µ
PD75402A’s I/O map. The items shown in this table have the following meaning.
• Symbol: A name to indicate the address of the built-in hardware. It can be described in
the instruction’s operand column. IME is excepted, however.
• Number of manipulatable bits: The number of applicable processing bits when operating the relevant
hardware. Such symbols as R/W, indicate whether the relevant hardware is
readable/writable or not.
R/W : Readable/Writable
R : Readable
W : Writable
• Bit manipulation addressing: The applicable bit manipulation addressing when bit manipulating the relevant
hardware.