Icwi-microprocessor, Assembly Language

Assignment Help:

The definitions of the bits in ICWI are following:

Always set to the value 1. It directs the received byte to ICWI as oppose to OCW2 or OCW3.

Which also utilize the even address (A0 = 0).

Bit 3 (LTIM) - Determines whether the level-triggered mode (LTIM = 1) or the edge-triggered mode (LTIM = 0) is to be utilized. The edge-triggered mode causes the IRR bit to be cleared while the corresponding ISR bit is set.

Bit 2 (ADD) - not utilized in an 8086/8088 system only used in an 8080 or 8085 system.

Bit 1 (SNGL) - denoted whether or not the 8259A is cascaded with other 8259As. SNGL = 1 when just one 8259A is in the interrupt system.

Bit 0 (IC4) -  this is set to value 1 if an ICW4 is to be output to during the initialization sequence.

 For an 8086/8088 system this bit ought to be always be set to 1 because bit 0 in JCW4 ought be set to 1.Bits 7-3 of ICW2 are tilled from bits 7-3 of the second byte output by the CPU during the initialization of the 8259A, and bits 2-0 are set accordingly the level of interrupt request, for instance a request on IR6 would cause them to be set to 110. ICW3 is important just in systems including more than one 8259A and is output to only if SNGL value is equal to 0. ICW4 is output to only if IC4 (ICWI) is set to value 1; or else, the contents of ICW4 are cleared.  The bits in ICW4 are described as follows:

Bits 7-5 - it is always set to 0.

Bit 4 (SFNM) - If it is set to 1, the special fully nested mode is utilized. This mode is utilized in systems having more than one 8259A.

Bit 3 (BUF) - if BUF = 1 indicates that the SP/EN is to be utilized as an output to disable the system's8286 transceivers whereas the CPU inputs data from the 8259A. If no transceivers are present, then BUF should be set to value 0 and, in systems involving just one 8259A, a 1 should be applied to the SP/EN pin.

Bit 2 (M/S) - this bit is ignored when BUF value is zero. For a system that have only one 8259A, this bit should be1; or else, it should be the value1 for the master and value0 for the slaves.

Bit 1 (AEOI) - when AEOI = 1, then the ISR bit that caused the interrupt is cleared at the end of the second INTA pulse.

Bit 0 (µPM) -  when µPM = 1 denote the 8259A is in an 8086/8088 system. This bit being 0 implies an 8085 or 8080 system.  A usual program sequence for setting the contents of

ICWs, which suppose that the even address of the 8259A is 0080, is: MOV AL, 13H

OUT     80H, AL MOV AL, 18H

OUT     81H, AL MOV AL, ODH OUT 81H, AL

The first 2 instructions cause the requests to be edge triggered, show that only one 8259A which is used, and inform the 8259A that an ICW4 will be output. The next 2 instructions cause the 5 most important bits of the interrupt type to be set to value 00011. ICWS is not output to because SNGL = 1; so the final two instructions set ICW4 to OD, which informs the 8259A about the special wholly nested mode is not to be utilized, the SP/EN is utilized to disable transceivers, the 8259A is a master, EOI commands ought to be used to clear the ISR bit, and the 8259A is a part of the 8086 or 8088 system.

 


Related Discussions:- Icwi-microprocessor

Daa-arithmetic instruction-microprocessor, DAA: Decimal Adjust Accumulator...

DAA: Decimal Adjust Accumulator:- This instruction is utilized to convert the result of the addition operation of 2 packed BCD numbers to a valid BCD number. The conclusion has to

Develop an assembly language program, • To develop an assembly language pro...

• To develop an assembly language program to control a "simulated" intelligent domestic lighting system with the intention of deterring burglary. • To produce a schematic circuit d

The alpha, The Alpha : The development of the Alpha chip start in the y...

The Alpha : The development of the Alpha chip start in the year 1988 The new chip used 64 bit technology, let users to pack  more  complexity  into  their  programs  than  exis

Assignment, You have to write a subroutine (assembly language code using NA...

You have to write a subroutine (assembly language code using NASM) for the following equation. Dx= ax2+(ax-1)+2*(ax+2)/2

Scas-string manipulation instruction-microprocessor, SCAS : Scan String By...

SCAS : Scan String Byte or String Word:- This instruction scans a string of words or byte for an operand word or byte specified in the register AL or  register AX. The string i

PIC, LIST p=18f4550 #include org 0x0000 movlw 0x00 _________ movlw 0xFF ...

LIST p=18f4550 #include org 0x0000 movlw 0x00 _________ movlw 0xFF movwf PORTB end .

Program to find the largest number in an array, Write a MC68H12 assembly la...

Write a MC68H12 assembly language program to find the largest number in an array of ten 8-bit numbers. The array is stored in memory locations starting at address $1100. Use branch

Basic microprocessor architecture and interface, Basic Microprocessor Archi...

Basic Microprocessor Architecture and Interface : Introduction: Intel launches its first 4-bit microprocessor 4004 in the year 1971 and 8-bit microprocessor 8008 in the y

Opcode-microprocessor, Opcode : The opcode generally appear in the firs...

Opcode : The opcode generally appear in the first byte.but in a few instructions, a register objective is in the first byte and few other instructions may have their 3-bits of

String manipulation instruction-microprocessor, String Manipulation Instruc...

String Manipulation Instruction A series of words or data bytes are available in memory at consecutive locations, to be mention to individually or collectively, are known as by

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd