8086 questions.... a. There are 40 pins in the original 8086 microprocessor. Wri

Question

8086 questions.... a. There are 40 pins in the original 8086 microprocessor. Write the name of the pin that best matches the given description. ______ If this pin is active, the databus is being read into the CPUs internal data bus. _________ Works with the WAIT instruction: is set when the wait instruction is executed. _______ If the pin is low then the CPU will idle. When high, the CPU is 'ready' ________ This is the Interrupt request pin, pin gets set high when an external interrupt is present _________ Non-maskable interrupt, this pin will ignore the interrupt flag. When this present signal is active, the CPU will automatically use interrupt vector table 2.....used for gnarly interrupts. _________ If this pin is high for at least 4 clock cycles, the CPU is reset. _________ this pin selects the mode of processing ___________ Multiplexed pin, has bus high enable to signal that the mulitplexed address/data lines 15-0 contain address information __________ Heartbeat of the CPU. ________ power ________ ground

Explanation / Answer

1. DT/R

It stands for Data Transmit/Receive signal and is available at pin 27. It decides the direction of data flow through the transreceiver. When it is high, data is transmitted out and vice-a-versa.

2. TEST

TEST pin is examined by the "WAIT" instruction. If the TEST pin is Low, execution continues. Otherwise the processor waits in an "idle" state. This input is synchronized internally during each clock cycle on the leading edge of CLK.

3. READY

It is available at pin 32. It is an acknowledgement signal from I/O devices that data is transferred. It is an active high signal. When it is high, it indicates that the device is ready to transfer data. When it is low, it indicates wait state.

4.INTR

It is available at pin 18. It is an interrupt request signal, which is sampled during the last clock cycle of each instruction to determine if the processor considered this as an interrupt or not.

5.RESET

It is available at pin 21 and is used to restart the execution. It causes the processor to immediately terminate its present activity. This signal is active high for the first 4 clock cycles to RESET the microprocessor.

6.MN/$overline{MX}$

It stands for Minimum/Maximum and is available at pin 33. It indicates what mode the processor is to operate in; when it is high, it works in the minimum mode and vice-aversa.

7.ALE

It stands for address enable latch and is available at pin 25. A positive pulse is generated each time the processor begins any operation. This signal indicates the availability of a valid address on the address/data lines.

8. Vcc

pin 40 used for power supply

9.GND

pin 1 and 20 used

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