PPT – 8. 08. 6 Addressing Modes Power. Point presentation . P HEAD Department of Instrumentation Technology Medical Electronics M. S. Ramaiah Institute of Technology, Bangalore 2. Topics to be covered. 8086 CPU ARCHITECTURE. The microprocessors functions as the CPU in the stored program model of the digital computer. Its job is to generate all system timing signals. What are the flags in 8086? Microprocessor 8086 1. 8086 Microprocessor Dr. Gopikrishna Assistant Professor of Physics Maharajas College Ernakulam 2. En processor, Central Processing Unit (engelsk initialism CPU), X86 assembly language is a family of backward-compatible assembly languages, which provide some level of compatibility all the way back to the Intel 8008. Program, data and stack memories occupy the same memory space. The total addressable memory size is 1MB KB. As the most of the processor instructions use 16-bit. Session 2. 4 2. 2/1. Interrupt Processing, Interrupt Vector table, Hardware Interrupts. Session 2. 5 2. 3/1. Expanding the Interrupt Structure Session 2. Interrupt Applications 3. INTERRUPTThe meaning of interrupts is to break the sequence of operation. While the cpu is executing a program,on interrupt breaks the normal sequence of execution of instructions, diverts its execution to some other program called Interrupt Service Routine (ISR). After executing ISR , the control is transferred back again to the main program. Purpose of Interrupts. Interrupts are particularly useful when interfacing I/O devices that provide or require data at relatively low data transfer rate. Interrupt Sources. Hardware Interrupts (External Interrupts) ex NMI, INTR Software Interrupts (Internal Interrupts and Instructions) ex INT n (Software Instructions) 6. Interrupt Response. ISR procedure PUSH registers - - - POP registers. Mainline Program. 8086 microprocessor has two units; Execution Unit (EU) and Bus Interface Unit (BIU). They are dependent and get worked by each other. Below is a short description of. A DOS (8086) cross compiler is currently being developed in FPC trunk (the development version). It started as a hobby project meant to explore how to port.PUSH Flags CLEAR IF , TF PUSH CS PUSH IP FETCH ISR ADDRESSPOP IP POP CS POP FLAGSIRET 7. It decrements SP by 2 and pushes the flag register on the stack. Disables INTR by clearing the IF. It resets the TF in the flag Register. It decrements SP by 2 and pushes CS on the stack. It decrements SP by 2 and pushes IP on the stack. Fetch the ISR address from the interrupt vector table. It is one byte instruction whereas other instructions of the form INT nn are 2 byte instructions. If INT 0 is placed after a signed number arithmetic as IMUL or ADD the CPU will activate INT 0. F 1. In case where 0. F 0 , the INT 0 is not executed but is bypassed and acts as a NOP. P HEAD Department of Instrumentation Technology Medical Electronics M. S. Ramaiah Institute of Technology, Bangalore 2. HARDWARE INTERRUPTSNMI Non maskable interrupts INTR Interrupt request. Edge triggered Input NMI INTR INTA 8. Level triggered Input. Response to INTR input 2. Complete 8086 instruction set. CALL procedure name label 4-byte address: Transfers control to procedure, return address is (IP) is pushed to stack. Hardware Interrupts. NMI TYPE 2 Interrupt INTR Between 2. H and FFH 2. 7Interrupt priority structure Interrupt Priority Divide Error, INT(n),INTO Highest NMI INTR Single Step Lowest 2. University Questions. Aug 2. 00. 5 CSE/ISE (VTU) Explain the sequence of operation follow after the execution of INTR interrupt. What do you mean by interrupt priorities? List out interrupt priorities in 8. Explain why this is required. Explain the reasons for this separate IRET instruction (4 marks) 3. University Questions. Aug 2. 00. 5 EC/TC (VTU) What is an Interrupt Vector? Explain in detail the events that occur when a real mode interrupt becomes active. What is Interrupt vector table? Briefly describe the conditions which cause the 8. Interrupts Type 0 , Type 1, Type 2, Type 3, Type 4 What do you mean by Interrupt priorities? State the Interrupt priorities of 8. Applications of NMI Power failure detection circuit 7. NMI7. 4LS1. 22 Monoshot 3. The output of the isolator is shaped by Schmit trigger inverter that provides a 5. Hz pulse to the trigger Input of monoshot. The value of R C are chosen so that pulse width of 2 AC I/P periods. LS1. 22s retriggarable as long as a. Q 1, Q 0 If the AC power fails, no trigger pulses to monoshot hence Q 0, Q 1interrupting the microprocessor 3. The ISR stores the contents of all internal registers and other ddc into a battery- backed up memory The filter capacitor (normally high), the voltage decays exponentially provides energy for the memory after the AC power ceases. INTR and INTAInterrupt request input (INTR) is level sensitive, it must be held at logic 1 level until it is recognized. The microprocessor responds to the INTR input by pulsing INTA output in anticipation of receiving an interrupt vector type number as data bus (D7 D0) 3. INTR LOCK INTA D7- D0. Vector number. Interrupt type is inserted in the second pulse INTA 3. Minimum mode. IO/M 0 I/O operation during the INTA bus cycle LOCK 0 To avoid BIU from accepting a hold request between two INTA cycles 3. Maximum mode. Status lines s. INTA via 8. 28. 8 Lock 0 from T2 of first cycle until T2 of the second cycle to prevent the 8. RQ/GT input 3. 9Using a 3 state buffer for INTAD7- D0 (low data byte) 8. INTR INTA7. 4LS2. G 2. G1. 0 K5v. Pull up resistors. Switch open 1 Switch closed 0. Switches. S0 S7. S6 4. Microprocessor outputs INTA that is used to enable 7. LS2. 44 The octal buffer applies the interrupt vector type number to the data bus in response to INTA The vector type number is easily changed with the DIP switches. Making the INTR input Edge- trigger. Reset 4. 2RESET signal initially clears the flip- flop so that no interrupts requested when the system is powered Clock input becomes an edge- triggered interrupt request input Clear I/P is used to clear the request when the INTA is output by the microprocessor 4. Expanding the Interrupt structure. D7 D0 8. 08. 6 INTA INTR8. LS2. 44 1. G 2. G5v. VCC1. 0K. IR0. IR1. IR7 4. 4 If any of the IR input becomes a logic 0, then the output of the NAND gate goes to logic 1 and requests an interrupt through INTR input. Bit D7 1 4. 6HARDWARE INTERRUPT APPLICATIONSASCII Keyboard.
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