Page 128 - Digital Electronics by harish

This is an active low signal. It will be 0 during memory
32 read and I/O read operation.

This is an active low signal. It will be 0 during memory
31 write and I/O write operation.

Peripheral initiated signals
This pin is used for interfacing slow devices with the
35 READY microprocessor.

39 HOLD DMA (Direct Memory Access) signals:
HOLD (hold request)
38 HLDA HLDA (hold acknowledge)

Clock signals

Used for connecting the crystal for generating the clock
1, 2 X 1, X 2 signal.

37 CLK OUT Clock signal for the peripheral devices.

Reset signals

Used to apply reset signal to the microprocessor. When this pin
goes low, the microprocessor is reset and begins executing the
36 instruction from the memory location 0000. All the registers
inside the microprocessor is reset to zero.

RESET Used to reset the peripheral devices.
3
OUT
Interrupt signals

6 TRAP
7 RST 7.5 Interrupt request input signals to the microprocessor.
8 RST 6.5
9 RST 5.5
10 INTR
Interrupt Acknowledgesignal from the microprocessor to the
11 peripheral devices.

Serial I/O signals

5 SID Serial Input Data. Used to receive serial data bits.

4 SOD Serial Output Data. Used to transmit serial data bits.

Power supply and Ground signals

40 V CC Power supply pins.
+5V to V CC
20 V GND to V SS
SS

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