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MSM80C85AHRS/GS/JS

SUPPLEMENTARY EXPLANATION

(1) SIM instruction: The execution of the SIM instruction uses the contents of the accumulator

to mask MSM80C85AH’S interrupts.

Accumulator Setting Value

R7.5 (Reset interrupt 7.5 Flip-flop): When this bit is set to 1, the edge detecting flip-flop

of RST 7.5 interrupt is reset.

MSE (Mask Set Enable): When this bit is set to 1, the interrupt mask bits are valid.

M7.5 (Mask RST7.5): When this bit is set to 1 and MSE bit is set to 1, RST7.5 interrupt is

masked.

M6.5 (Mask RST6.5): When this bit is set to 1 and MSE bit is set to 1, RST6.5 interrupt is

masked.

M5.5 (Mask RST5.5): When this bit is set to 1 and MSE bit is set to 1, RST 5.5 interrupt is

masked.

—

Bit 7

—

6

—

5

R7.5

4

MSE

3

M7.5

2

M6.5

1

M5.5

0

(2) RIM instruction: When the contents of the accumulator are read out after RIM instruction has

been executed, MSM80C85AH interrupt status can be known.

Accumulator Reading Value

—

Bit 7

17.5

6

16.5

5

15.5

4

IE

3

M7.5

2

M6.5

1

M5.5

0

17.5 (Pending RST7.5): When RST7.5 interrupt is pending, "1" is read out.

16.5 (Pending RST6.5): When RST6.5 interrupt is pending, "1" is read out.

15.5 (Pending RST5.5): When RST5.5 interrupt is pending, "1" is read out.

IE (Interrupt Enable Flag): When interrupt is Enable, "1" is read out.

M7.5 (Mask RST7.5): When RST7.5 interrupt is masked, "1" is read out.

M6.5 (Mask RST6.5): When RST6.5 interrupt is masked, "1" is read out.

M5.5 (Mask RST5.5): When RST5.5 interrupt is masked ,"1" is read out.