UPD75236GJ データシートの表示（PDF） - NEC => Renesas Technology

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UPD75236GJ

4-BIT SINGLE-CHIP MICROCOMPUTER

NEC => Renesas Technology 

µPD75236

2.3 MEMORY MAPPED I/O

As shown in Fig. 2-1, the µPD75236 employs the memory mapped I/O with the peripheral hardware includ-

ing input/output ports and timers mapped at addresses F80H to FFFH in the data memory space. Thus, there

are no special instructions to control the peripheral hardware and all operations are controlled by memory

manipulation instructions. (Some hardware control mnemonics are available to make the program easy to

understand.)

When operating the peripheral hardware, the addressing modes listed in Table 2-3 can be used.

Manipulate the display data memory, key scan register and port H mapped at addresses 1A0H to 1FFH by

specifying memory bank 1.

Table 2-3 Addressing Modes Applicable when Manipulating the

Peripheral Hardware at Addresses F80H to FFFH

Bit manipulation

4-bit manipulation

8-bit manipulation

Applicable Addressing Mode

Specify by direct addressing mem.bit with MBE = 0 or

(MBE = 1, MBS = 15)

Specify by direct addressing fmem.bit irrespective of

MBE and MBS

Specify by indirect addressing pmem.@L irrespective

of MBE and MBS

Specify by direct addressing mem with MBE = 0 or

(MBE = 1, MBS = 15)

Specify by register indirect addressing @HL with

(MBE = 1, MBS = 15)

Specify by direct addressing mem with MBE = 0 or

(MBE = 1, MBS = 15) (mem is an even address.)

Specify by register indirect addressing @HL with

MBE = 1 and MBS = 15 (L register contents are even.)

Applicable Hardware

All hardware devices enabled for bit

manipulation

IST0, IST1, MBE, RBE,

IE×××, IRQ×××, PORTn. 0 to 3

PORTn.

All hardware devices enabled for 4-bit

manipulation

All hardware devices enabled for 8-bit

manipulation

Table 2-4 shows the µPD75236 I/O map.

In the table, each item has the following meanings:

• Symbol ............. Name indicating the on-chip hardware address.

Can be described in the instruction operand column.

• R/W ................... Indicates whether the corresponding hardware is enabled for read/write.

R/W : Read/write enable

R : Read only

W : Write only

• No. of manipulatable bits ........ Indicates the number of applicable bits before operating the corre-

sponding hardware.

• Bit manipulated addressing .... Indicates the applicable bit manipulated addressing before operating

the applicable hardware.

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