8085 Architecture-

The MP is a programmable digital device designed wid registers, flip-flops & timing elements. The MP has a set of instructions designed internally to manipulate data , control timing of various operations & communicate with such peripherals(devices as memory & I/O) .The internal logic design of MP called its architecture determines how and when various operations are performed by MP.
The system bus provides path for flow of binary informations (data and instructions).
The accumulator connects data bus & ALU ( ALU performs all data manipulations such as incrementing a no. or adding 2 no.s etc). Temporary register feeds ALU's other input, this register is invisible to programmer & is controlled automatically by MP control circuitary.
 Flags are collection of flip-flops that indicates certain characteristic of result of most recent airthmetic and logic operation performed by ALU.
For ex- 0 (zero flag) is set if result of an operation is zero. Zero flag is tested by JZ instruction .

JZ instruction (Add/label):-

• Jump statement- Jump to address if zero is encountered.
• The instruction register , instruction decoder ,control & timing logic, program counter are used for fetching instruction from memory and directing their execution. 

 

Tri-State logic devices--

Tri-State logic devices-

an essentials for proper functioning of bus-oriented system in which same bus line are shared by several components

Tri-state Inverter-

                                                                               

Buffer is used primarily to increase the current driving capability of logic circuits. It is commonly used to increase the capability of data & address bus . Ex. of tri-state buffer-1) IC 74LS244 ---> Octal Buffer

                                                                                                       2)IC 74LS240 etc. LS-low power schottky TTL.

MP-based system with BUS ARCHITECTURE----

System bus = address bus + data bus + memory + I/O control lines + CPU + bus control lines + utility bus

Bus- 

electrical lines thru which s/g flows frm peripheral -i/o devices . The system bus is a communication path btw mp and peripherals. it is nothing but a grp of wires to carry bits. all peripherals(and memory) share d same bus. However, mp communicates with only one peripheral at a time . Timing is provided by the control unit of mp.

Even though a mp may have a wide variety of architecture features & capabilities, but all of them should have following functional components.

Register Section-

Contains some on-chip registers as hardware which are used for temporary storage of data or info or address of data.

ALU-

It is also a hardware unit which is used to perform primitive arithmetic operation ,ex- +ve, -ve, & logical operation -> and ,or , ex-or etc.

Interface section-

it provides some hardware i/p , o/p lines thru which mp or CPU communicates with outside world .

Timing and control unit-

it provide necessary timing and control s/g to all operation in MP . It is HEART of a MP which coordinates and controls various activities within MP and btw MP & external devices. 

so here is about ADDRESS BUS(address lines) and DATA BUS(data lines)

ADDRESS LINES(ADDRESS BUS)-

the address lines originate from the CPU, the exact no. of these lines depends on the specific CPU,the larger the no. of lines,the greater the capacity to provide alternative addresses(binary no.s) and hence greater addressing capability. With 'n' address lines,the addressing capability is 2ⁿ 

Sometimes the o/p lines act as chip selects or chip enables. The set of address lines is also called Address Bus.

DATA LINES(DATA BUS)-

 the no. of data lines ,like that of the address lines vary with the specific CPU. Like the address bus the data lines are often shown collectively as data bus. The data bus is bidirectional, as the information on the address bus always flows out of the CPU so address bus in unidirectional , the data can flow both out of  the CPU as well as into the CPU on data bus.

The display-

through thedisplay element the computer sends out information, such as results of any calculation ,it has carried out according to some program .The display element can be of a wide variety of types:seven segment display wid each segment made of LEDs or LCD segments and finally the CRT display which enables display a lot of information in one group.

the display interface-

Display interface is necessary for taking information from the computer operation controller and making it available to the display device in appropriate format .The display interface can be met bt ICs specially designed for such purposes.

ROM-

it is a permanent memory area in which the programs once stored are not altered when the power to the computer is turned OFF and also cant be overwritten.For a blank ROM,the manufacturer supplies the device without any information in it,information can be entered electrically into the memory space which is called the burning of ROM.

RAM-

besides ROM area, every computer has some memory space for temporary storage of data as well as for programs under development. The memory devices used for this purpose are called RAMs or Read-Write Memory.The contents of the RAM memory are not permanent and are altered when the power is turned off. RAM memory contents are not retained when power goes off ,the RAM memory is considered to be volatile memory. When alternate power such as in the form of a battery is provided the RAM is then said to have a battery back-up.

CPU-

It co-ordinates all operations of a microcomputer . It feches programs stored in the ROMs or RAMs and executes the instructions depending on a specific instruction set,which is the characteristic of each type of CPU and which is recognised by the CPU. The signals associated with the CPU are address lines , data lines ,read lines , write lines , control lines , interrupt signals etc. 

Keyboard-

it consists of a set of keys ,the component through which a user can either enter a program , put necessarry data and interact with the computer through appropriate commands .It contains few or large no. of keys depending on the type of work . eg. ASCII... etc

Keyboard interface-

the keyboard operation ,ie pressing of keys doesnot usually generate s/nls which can be directly used by the computer operation controller , it is necessary to transform the switch closure information into a format that can be recognised by the computer. It can be done by a keyboard interface which takes the input from the keyboard and generates outputs in suitable format based on information which is characteristics of key pressed.

Hello friends , here is d all basics about Microprocessor and microcontroller . hope it wll help u out in understanding this subject easily.

so here we start our blog from d basic thing about mp and mc and that is 

A MICROCOMPUTER- 

The crucial components of a microcomputer are -

• keyboard-

through which instructions are entered into microcomputer.

•  the display device-  

through which the microcomputer displays its messages and results.

• rom-

in which permanent programs are stored.

• ram-

in which temporary programs and trail programs are written and also used for storing temporary information during program execution.

• CPU-

it manages the entire microcomputer operation ie input,processing and displays the o/p through interfaces.