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M37733S4

16-BIT CMOS MICROCOMPUTER

MITSUBISHI ELECTRIC  

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MITSUBISHI MICROCOMPUTERS

M37733S4BFP

16-BIT CMOS MICROCOMPUTER

PROCESSOR MODE

The bits 0 of processor mode register 0 as shown in Figure 8 is used

to select which mode of microprocessor mode, and evaluation chip

mode.

Figure 9 shows functions of P00/A0 to P47 pins in each mode.

The external memory area also changes when the mode changes.

Figure 10 shows the memory map for each mode.

The accessing of the external memory is affected by the BYTE pin,

the bit 2 (wait bit) of processor mode register 0, and bit 0 (wait selection

bit) of processor mode register 1.

• BYTE pin

When accessing the external memory, the level of the BYTE pin is

used to determine whether to use the data bus as 8-bit width or 16-

bit width.

The data bus width is 8 bits when the level of the BYTE pin is “H”,

and P20/A16/D0 to P27/A23/D7 pins become the data I/O pins.

The data bus width is 16 bits when the level of the BYTE pin is “L”,

and both P20/A16/D0 to P27/A23/D7 pins and P10/A8/D8 to P17/A15/

D15 pins become the data I/O pins.

When accessing the internal memory, the data bus width is always

16 bits regardless of the BYTE pin level.

7 654 321 0

Address

0

1

Processor mode register 0 5E16

Processor mode bit

0 : Microprocessor mode

1 : Evaluation chip mode

This bit must be “1”

(becomes “1” after reset release)

Wait bit

0 : Wait

1 : No Wait

7 654 3210

Address

Processor mode register 1 5F16

Wait selection bit

0 : Wait 0

1 : Wait 1

Software reset bit

Reset occurs when this bit is set to “1”

Interrupt priority detection time selection bit

0 0 : Internal clock ! 7

0 1 : Internal clock ! 4

1 0 : Internal clock ! 2

This bit must be “0”

Not used

Fig. 8 Processor mode register bit configuration

10

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