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Intel 8086 and 8088
The Intel 8086/8088 family of microprocessors is a 16 bit architecture on a 16 bit (8086) or an 8 bit (8088) bus. The 8088 was the processor in the original IBM PC, and has evolved into the most popular processor used today in PC's and servers.
1,056 Questions
What is execution unit and bus interface unit?
In the 8086/8088, the execution unit is the part of the processor known as the CPU. It executes the instructions and generates the results. The bus interface unit, on the other hand, is the part of the processor that handles reading and writing to memory. The two are somewhat loosely coupled, with the bus interface unit attempting to always be ahead of the execution unit, i.e. using the cache, so that the execution unit's wait time is minimized and performance is maximized.
Why the gray code is also known as the reflected binary code?
Gray Code is known as reflected binary code (RBC) because Frank Gray's 1947 patent application contained the following paragraph:
The binary code with which the present invention deal may take various forms, all of which have the property that the symbol (or pulse group) representing each number (or signal amplitude) differs from the ones representing the next lower or next higher number (or signal amplitude) in only one digit (or pulse position). Because this code in its primary form may be built up from the conventional binary code by a sort of reflection process and because other forms may in turn be built up from the primary form in similar fashion, the code in question, which has as yet no recognized name, is designated in this specification and in the claims as the "reflective binary code."
What he meant by this "reflection process" is that any n-bit RBC sequence could be generated recursively by reflecting the n-1 RBC sequence for all n>0. The minimum RBC sequence is n=1:
0, 1
To generate the n=2 sequence, we reflect the n=1 sequence which simply reverses it:
1, 0
We then prefix the original n=1 sequence with a 0 bit and prefix the reflected sequence with a 1 bit:
00, 01 11,10
Finally, we concatenate these two sequences to produce the n=2 sequence:
00, 01, 11, 10
Note that this sequence represents the decimal sequence 0, 1, 2, 3, and not 0, 1, 3, 2 as per conventional binary notation.
Repeating the process with the n=2 sequence we can produce the n=3 sequence, then the n=4 sequence, and so on, for as many bits as we require.
Note that the sequence is cyclic. The final binary value for any given sequence differs from the first by only one digit (as is common throughout the sequence), thus when we reach the end of an RBC sequence we can simply start over again. This led to RBC becoming known as a "cyclic permutation code" in a 1953 patent. Other names for RBC include "minimum error code" and "the Bell Telephone Gray Code", a reference to Frank Gray's research work at Bell Labs. Today, the term Gray Code almost always refers to Reflected Binary Gray Code, or RBGC, as per Gray's original patent.
We can easily convert any conventional binary value to its RBGC equivalent such that:
rbgc(n) = n ^ (n >> 1)
>> is bitwise right shift and ^ is bitwise exclusive or.
For the decimal value 40 (binary 101000) we find:
101000 ^ (101000 >> 1) = 101000 ^ 010100 = 111100
Thus RBGC (101000) is 111100.
RBGC is typically used wherever we have a sequence of consecutive values and need to represent them in such a way that when we access a value mid-transition, we know that any read error can only be one value up or down from what it should be. For instance, without RGBC, the transition from 3 to 4 would result in 3 bits changing simultaneously (011 to 100), however with mechanical representations, there may be a small but significant delay in the bit transitions so we might read 000, 001, 010, 011, 100, 101, 110 or 110, depending on which bit changes first and at what stage in the transition we read the value. The more bits that change, the greater the range of errors we might encounter. But with RBGC, we guarantee that during the transition phase from 3 to 4 we either read a 3 or we read a 4 because only 1 bit can ever be in transition.
Define stack.discuss push and pop operation?
A stack is a region of memory that you store things, and retrieve them in the reverse order of storage.
Think of it as a stack of papers. You write something down on a piece of paper, and then you put that paper in a stack, specifically on the top of the stack. This is called a push operation. If you want to go and do something else, such as service an interrupt or call another function, you create more pieces of paper and you push them onto the top of the stack as well.
Under normal conditions, you cannot access anything on the stack below the top. I say "normal" because the architecture of the processor allows you to access chunks of memory contained within the stack, relative to the base pointer BP, allowing you to pass arguments and store temporary variables in what is called a stack frame.
The reverse of push is called pop, and it is equivalent to taking a piece of paper off of the top of the stack and throwing it away - or using it, whatever you want - but that action exposes the next piece of paper, which is now the new "top of stack".
How macro calls within macros are handled?
'=============>>
Public Sub Main()
'Your code
Call One
'your code
End Sub
'<<=============
'=============>>
Public Sub One()
MsgBox "Hi from One"
End Sub
'<<=============
> Does it matter where the other macros are stored or is it
> better to have them all in one module?
Unless there are a larger number of macros, they can be stored in a single
module. However, for organisational reasons, it is usually better to store
macros by type in different modules.
Regards
Rollick
Explain the function of BIU and EU in 8086?
biu stands for bus interface unit and eu stands for execution unit.
In 8086 microprocessor BIU fetches the instructions and places in the queue.
The Eu executes the fetched instruction and places the result in the registers
das
There are many different instructions and registers in the 8086/8088. The question is too broad. Please ask a more specific question. Alternatively, you can consult a good book, such as "The 8086/8088 Primer", Second Edition, Stephan P. Morse, Hayden Book Company, or any of a wide variety of other books.
How many data lines are necessary in 16-bit microprocessor?
It depends. From the CPU's point of view, 16 data lines are necessary in a 16-bit microprocessor. Some implementations, however, such as the 8088, use an 8-bit bus, instead of like the 8086, which uses a 16-bit bus. The Bus Interface Unit (BIU) handles the conversion, packing, and unpacking transparently to the Execution Unit (EU or CPU).
Define briefly about procedures and macros in microprocessor?
Procedures-Procedure is the set of codes written in other module used 2 solve a specific task and can be included in the main program when an instruction CALL is used in the program.
Macro is also the set of codes used in the 'main program' or same module used to solve a specific task. Macros can be called in the program with the syntax using syntax-MACRO_NAME(actual variables). But the macros should be included in the program with the syntax MACRO_NAME(dummy variables). Dummy and actual variables should match.
Why filo is not used in stack?
FILO is an acronym of "first in last out". If we imagine a stack of plates, the first plate is at the bottom of the stack and is therefore the last to be removed from the stack. Thus FILO is used when referring to a stack. We use a stack when we wish to process elements in the reverse order they arrive, always processing the newest arrival first. Stacks are useful in backtracking algorithms and are a fundamental aspect of the call-and-return mechanism.
FIFO, on the other hand, is an acronym of "first in first out" and is synonymous with "first come, first served". As such, FIFO applies to queues rather than stacks. We use a queue when we wish to process elements in the same order they arrive.
What are applications of 8086 microprocessor?
8086 main application is to evaluate the arithmetic operations in any systems that uses 8086
Stock exchange symbol for DaimlerChrysler AG (USA).
AnswerActually, since this is in the Computer category, I think the answer is that DCX is the file format used for storing multi-page PCX images. It also may refer to the common filename extension for MS Visual FoxPro.
What do BIU and EU stand for and what are their functions?
biu stands for bus interface unit and eu stands for execution unit.
In 8086 microprocessor BIU fetches the instructions and places in the queue.
The Eu executes the fetched instruction and places the result in the registers
A segment address is the contents of a segment register, CS, DS, ES, or SS. It is used after effective address generation to provide an offset in physical memory, by multiplying the segment register by 16 and then adding it to the effective address, giving a 20 bit address.
This gives you addressability to 65536 segments of 65536 bytes, each separated by 16 bytes.
The register used is usually implicit based on use; CS for code, DS for data, ES for certain string operations, and SS for stack. A segment override prefix can be used to select a different segment register.
What is lookup table in microprocessor?
The lookup table in a microprocessor is a system that helps replace the runtime computations. It replaces them with an easier index operation.
How do you write a assembly language program to subtract two 8 bit numbers?
Code for 8085 microprocessor.
MVI A, Number1
SUI Number2
The code works as follows:
Register A = Number1 - Number2
List out the similarities between call-ret and push pop instructions?
In the case of call-return, that something is the program counter. In the case of push-pop, that something is up to the programmer, and it can be one of AF, BC, DE, or HL.
What is latch in microprocessor?
Latch are just like inputs which are used to set or reset the output for a given combination.
Ask the mechanics. I drove Albion Lowlanders for Alexnders (Milngavie Garage 1968-70) and Hignland (summer 1973). I had good all round vision, the Alexander bodied sliding cab door so I could keep it open in warm weather, substantial and adjustable seat, good flat angle for the steering wheel, plenty of space to left of seat for gearstick in manual versions, unlike Bristol Lodekka and AEC, and easy control of column gearstick in pneumocyclic versions. Passengers to my recollection liked it as it was a Step On (no steps up) with a flat floor and stairs diectly in front of the door. Also if passengers came to the door seeking the next stop, and the conductor was upstairs or otherwise engaged, they could rap the driver cab window, the driver could see them, and would stop. On boarding, unless the conductor was actually at the door the driver could better and clearly see the door, see if it was clear, close it and get going. From a crew and operation point of view this was one of the best buses on the road in it's day. Therefore I can only presume the aversion to the Albion (later Leyland) Lowlander was to do with operational cost or reliability or something like that. Operator's problem, not crew or passenger. I loved them. I am now 61 but still hold a PSV (or PCV as they call it now). I do think the change in these intitials defines the change which the gorgon Thatcher imposed on the bus industry with deregulation in the mid eighties. PSV was Public Service Vehicle. Service to the public, that's what it was for. PCV means Passenger Carrying Vehicle. Business definition only. Public Service has been edited out. That is the real shame for the bus industry as I knew it. The domination by the now small number of big companies providing bus services with smart and bang up to date fleets of vehicles is only a success story if it provides a service to the public at large, not just a highly profitable operation on guaranteed busy routes. I would love to drive an Albion or Leyland Lowlander again. Any chance?
What type of flags in 8086 and 8088 microprocessor and their uses.?
There are nine flags in the 8086/8088.
- SF - Sign Flag - The result is negative
- ZF - Zero Flag - The result is zero
- AF - Auxillary Carry Flag - A BCD carry occurred
- PF - Parity Flag - Indicates the oddness or evenness of the number of bits
- CF - Carry Flag - An unsigned carry occurred
- OF - Overflow Flag - A signed overflow/carry occurred
- DF - Direction Flag - Controls the direction of repeated string operations
- IF - Interrupt Flag - Enables or disables interrupts
- TF - Trace Flag - Controls the debug single step interrupt
In general, most of these flags are set as a result of some arithmetic or logical instruction and can be tested using the conditional branch instructions. Exceptions are DF, which controls the directionality of repeated string operations, IF, which controls interrupts, and TF, which controls debugging.
What is the history of the word burn for computers?
To write a write-once optical medium such as a CD-R, DVD-R, BD-R or HD DVD-R disc. Such a disc is considered "burned," because once recorded, it cannot be erased and rewritten. The term is also erroneously used for rewritable disks, such as CD-RWs and DVD-RWs, but rewritable media are not "burned;" they are "written." Burn means "once and done.
http://content.answers.com/main/content/img/CDE/_CDRBRN.JPG
You can see the "burned" part of this CD-R disc by noticing the slight change in reflectivity on the recording side. In this example, the arrow points to the end of the small recorded area, which is less than 6% of the 700MB capacity of the disc.
from answers.com
What is the use of .stack .data in starting lines of 8086 programming?
.STACK
reserves
.DATA
Below the ".DATA" line you should declare (and optionally define) your variables, so the compiler reserves the corresponding RAM for each of them.
Data works differently from stack, as the data segment will keep named values (the variables values) while the stack will not. The stack will grow as needed upto the maximum value defined in the .STACK
Why CMPS instruction is used in 8086 programming?
The CMPS instruction in the 8086/8088 is compare string. It iterates until CX is zero, or [DS:SI] is not equal to [ES:DI], incrementing (or decrementing if DF is set) SI and DI, and decrementing CX along the way.
How many address lines and data lines are required for a 128k x 8 memory system?
17 address lines and 8 data lines.
2^17=128k
What is exhaustive decoding with respect to microprocessor decoding?
You're in McMaster University in ELEC ENG 2DP4, aren't you? You're in McMaster University in ELEC ENG 2DP4, aren't you?
