Answer / boss

If an interviewer asks this question. i would first say, it doesn't make a lot of sense in comparing these 2.

However, we can compare an ISR and a Function in terms of the do's and don'ts while writing them.

function can have anythings. there is no restriction. But ISR has some restrictions.

1. It should be as small as possible
2. Hence no large functin calls allowed (NO to printf())
3. No blocking function calls from an ISR. It should not
try to take a semaphore. but can release a
semaphore(counting/binary)


There may be few more. Pls google and collect all

Answer / praveen

Main difference is If function is called it should be
processed by compiler where as ISR is processed only when
interrupt occur.function call can return some value .but ISR
not return any thing .

Answer / mahesh

ISR will be initiated by the hardware and the ISR will
clear the flag that has initiated the interupt when it
returns from the ISR. The function call is initiated by the
program.

Answer / bhavin

ISR runs in Interpret context ; where as function routine runs in thread context of Caller .

so during an interrupt total context switch happens and after returning from interrupt scheduler is invoked .

A function call is essentially just a jump instruction apart from PC and CPU reg saving no other context change hapnes ( T.ID, Process ID , address space etc) .

Answer / manohar

ISR has priority associate whereas function call doesn't
because of this stack structure of them are different.
If we look assembly code : function call has RET and ISR have
IRET.

Answer / ravi a joshi

There is no comparison between function call and an ISR.
Both are used in a completely different paradigm. Hence
comparison doesn't exist.

Answer / sunitakn

In case of a function call the arguments,local variables and
return address is stored in the stack where as in case of an
ISR, after executing the current instruction the context is
saved with no return value.

What is ALE? Explain the functions of ALE in 8085.

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What is the bit size of Itanium processor of Intel?

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in a sn SR latch made by using cross coupling of two nand gates, if both S andR inputs set o then it will result

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explain the trap input for the 8085.

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write an assembly code which can call function in a loop with al value from 0 to 9

5 Answers   Google,

What is a microprocessor?

0 Answers  

I have code and test bench however it is not working porperly. Need help to get it working. module fsm(clock,reset,coin,vend,state,change); \\these are the inputs and the outputs. input clock; input reset; input [2:0]coin; output vend; output [2:0]state; output [2:0]change; \\i need to define the registers as change,coin and vend reg vend; reg [2:0]change; wire [2:0]coin; \\my coins are declared as parameters to make reading better. parameter [2:0]NICKEL=3’b001; parameter [2:0]DIME=3’b010; parameter [2:0]NICKEL_DIME=3’b011; parameter [2:0]DIME_DIME=3’b100; parameter [2:0]QUARTER=3’b101; \\MY STATES ARE ALSO PARAMETERS . I DONT WANT TO MAKE YOU READ \\IN MACHINE LANGUAGE parameter [2:0]IDLE=3’b000; parameter [2:0]FIVE=3’b001; parameter [2:0]TEN=3’b010; parameter [2:0]FIFTEEN=3’b011; parameter [2:0]TWENTY=3’b100; parameter [2:0]TWENTYFIVE=3’b101; \\AS ALWAYS THE STATES ARE DEFINED AS REG reg [2:0]state,next_state; \\MY MACHINE WORKS ON STATE AND COIN always @(state or coin) begin next_state=0; \\VERYFIRST NEXT STATE IS GIVEN ZERO case(state) IDLE: case(coin) \\THIS IS THE IDLE STATE NICKEL: next_state=FIVE; DIME: next_state=TEN; QUARTER: next_state=TWENTYFIVE; default: next_state=IDLE; endcase FIVE: case(coin) \\THIS IS THE SECOND STATE NICKEL: next_state=TEN; DIME: next_state=FIFTEEN; QUARTER: next_state=TWENTYFIVE; //change=NICKEL default: next_state=FIVE; endcase TEN: case(coin) \\THIS IS THE THIRD STATE NICKEL: next_state=FIFTEEN; DIME: next_state=TWENTY; QUARTER: next_state=TWENTYFIVE; //change=DIME default: next_state=TEN; endcase FIFTEEN: case(coin) \\THIS IS THE FOURTH STATE NICKEL: next_state=TWENTY; DIME: next_state=TWENTYFIVE; QUARTER: next_state=TWENTYFIVE; //change==NICKEL_DIME default: next_state=FIFTEEN; endcase TWENTY: case(coin) \\THIS IS THE FIFTH STATE NICKEL: next_state=TWENTYFIVE; DIME: next_state=TWENTYFIVE; //change=NICKEL QUARTER: next_state=TWENTYFIVE; //change==DIME_DIME default: next_state=TWENTY; endcase TWENTYFIVE: next_state=IDLE; \\THE NEXT STATE HERE IS THE RESET default : next_state=IDLE; endcase end always @(clock) begin \\WHENEVER I GIVE A RESET I HAVE TO MAKE THE STATE TO IDLE AND VEND TO 1 if(reset) begin state <= IDLE; vend <= 1’b0; // change <= 3’b000; end \\THE CHANGE ALSO HAS TO BECOME NONE else state <= next_state; case (state) \\HERE WE DECIDE THE NEXT STATE \\ALL THE STATES ARE DEFINED HERE AND THE OUTPUT IS ALSO GIVEN IDLE: begin vend <= 1’b0; change <=3’d0; end FIVE: begin vend <= 1’b0; if (coin==QUARTER) change <=NICKEL; else change <=3’d0; TEN: begin vend <= 1’b0; if (coin==QUARTER) change <=DIME; else change <= 3’d0; FIFTEEN : begin vend <= 1’b0; if (coin==QUARTER) change <=NICKEL_DIME; else change TWENTY : begin vend <= 1’b0; if (coin==DIME) change <=NICKEL; else if (coin==QUARTER) TWENTYFIVE : begin vend <= 1’b1; change <=3’d0; end default: state <= IDLE; endcase end endmodule module test; \\THE INPUT IN THE FSM MODULE ARE REG HERE reg clock,reset; reg [2:0]coin; \\THE OUTPUT IN THE FSM MODULE ARE WIRES HERE wire vend; wire [2:0]state; wire [2:0]change; \\THE PARAMETERS AGAIN FOR THE COIN AND STATE parameter [2:0]IDLE=3’b000; parameter [2:0]FIVE=3’b001; parameter [2:0]TEN=3’b010; parameter [2:0]FIFTEEN=3’b011; parameter [2:0]TWENTY=3’b100; parameter [2:0]TWENTYFIVE=3’b101; parameter [2:0]NICKEL=3’b001; parameter [2:0]DIME=3’b010; parameter [2:0]NICKEL_DIME=3’b011; parameter [2:0]DIME_DIME=3’b100; parameter [2:0]QUARTER=3’b101; \\I MONITOR THE TIME,DRINK,RESET,CLOCK,STATE AND CHANGE FOR CHANGES. initial begin $display("Time\tcoin\tdrink\treset\tclock\tstate\tchange"); $monitor("%g\t%b\t%b\t%b\t%b\t%d\t% d",$time,coin,vend,reset,clock,state,change); \\NEW FEATURE: MY MACHINE HAS THE FACILITY TO DUMP VARIABLES SO THAT \\ I CAN VIEW THEM USING A VCD VIEWER. $dumpvars; $dumpfile("file.vcd"); // Dump output file. \\THIS IS WHERE THE COINS ARE ADDED. clock=0; reset=1; \\FIRST LETS RESET THE MACHINE #2 reset=0; coin=NICKEL; \\CHECK FOR STATE 1 #2 reset=1; coin=2’b00; #2 reset=0; coin=DIME; \\RESET AGAIN AND CHECK FOR STATE 2 #2 reset=1; coin=2’b00; #2 reset=0; \\RESET AGAIN AND CHECK FOR STATE 5 coin=QUARTER; #2 reset=1; coin=2’b00; #2 reset=0; \\RESET AGAIN AND CHECK FOR STATE 5 coin=NICKEL; #2 coin=NICKEL; #2 coin=NICKEL; #2 coin=NICKEL; #2 coin=NICKEL; #2 reset=1; coin=2’b00; #2 reset=0; \\RESET AGAIN AND CHECK FOR STATE 5 AND SO ON coin=NICKEL; #2 coin=DIME; #2 coin=DIME; #2 reset=1; coin=2’b00; #2 reset=0; coin=NICKEL; #2 coin=DIME; #2 coin=QUARTER; #2 reset=1; coin=2’b00; #2 reset=0; coin=NICKEL; #2 coin=NICKEL; #2 coin=NICKEL; #2 coin=DIME; #2 reset=1; coin=2’b00; #2 reset=0; coin=NICKEL; #2 coin=NICKEL; #2 coin=NICKEL; #2 coin=NICKEL; #2 coin=DIME; #2 reset=1; coin=2’b00; #2 reset=0; coin=NICKEL; #2 coin=NICKEL; #2 coin=QUARTER; #2 reset=1; coin=2’b00; #2 reset=0; coin=NICKEL; #2 coin=QUARTER; #2 reset=1; coin=2’b00; #2 $finish; end \\THE CLOCK NEEDS TO TICK EVERY 2 TIME UNIT always #1 clock=~clock; //always @(state) // coin=!coin; initial begin if (reset) coin=2’b00; end \\THIS IS WHERE I INSTANTIATE THE MACHINE fsm inst1(clock,reset,coin,vend,state,change); endmodule

0 Answers   Intel,

What are the different flags in 8085?

24 Answers   Spectra Innovations, TCS, Wipro,

Write the flags of 8086?

0 Answers  

Define microprocessor?

0 Answers  

Point out the differences between the 8086 and 8088 microprocessor?

0 Answers