midterm-studyNotes-of-the-micropreccessors.txt

Micropreccessor Midterm Notes

WEEK 1:

Computer has two basic principal:
- responding instrructions
- execute prerecorded instrructions

All computer has these:
Memory, enables computer to store temporarily data.
Mass storage device, store permanent large data.
Input device, data instructions.
Output device, display result.
Central Proccess Unit, heart of the computer. Execute everything.

What is microprecessor?
One of the most importants, acts as a brain of the computer system.
Controlling unit of CPU, very small, performs ALU operations,
communicates with external devices.

What is computer?
Accepts data from user.
Stores data and instructions in memory.
Process data.
Communicates the result.

Computer Units:
Input unit
Output unit
Memory unit
Central processing unit(CPU)

Central processing unit:
Fetches the instructions and data from peripheral devices.
Perform Arithmetic operations and logical decisions.
Controls the operations in all units.

	Various sub-blocks of CPU's:
		
		Arithmetic and Logical Unit (ALU):
		addition, substraction... AND OR NOT XOR...
		
		Timing and Control Unit:
		Controls entire operations being performed by system.

		Register:
		Vey small very fast memory, in CPU.
		Stores current data and instructions while in execution.

Memory Unit:
Stores the program statement, data, information supplied from input unit, 
final output.

Microprecessor:
Fetch the instructions stored in the main memory.
Identify the operations and the devices involved. everything connected to him.
Determines when to take action.

Microprecessor yerince CPU kullanılırsa Microcomputer == Personal Computer(PC) olur.

Microcontroller is designed for a very specific task to control a particular system.

Microprocessor Characteristics:
	Instructions Set
	Bandwith: The number of bit processed in a single instruction.
	Capability
	Clock Speed: Determines how many operations per second the processor can perform.
	Word Length: 8bit microprecessor can process 8bit data.
	Width of Data Bus: Number of bits that can be transferred.
	Width of Address Bus: Decides maximum size of the memory.
	Input/Output Adressing Capability: The maximum number of I/O ports accessed by the
	microprecessor.
	Interrupt Capability: It used to handle unpredicted events. Interrupts the microprecessor.
 
Features of Microprecessor:
Low cost
Small size
Low Power consumption
High Versatility
Extreme Reliability

Embedded system:
is nearly any computing system other than a desktop, laptop, or mainframe computer.
Single functioned, repeatedly.
Low cost, low power, small, fast.
Reactive and real-time.

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WEEK 2:

Binary Number System:

Digital systems have only two states. 0:OFF 1:ON
1Byte = 8bits
Binary to hexadecimal, group digits in fours then translate.
The 0x is for base 16. (0xA2F)  
The 0b is for base 2. (0b10101111)

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WEEK 3: NOT INCLUDED

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WEEK 4:

System Bus:
It is a pathway composed of cables and connectors to carry data between microprecessor and memory.
The network of wires or electronic pathyaws is called "Bus".
A 32bit bus means 32 parallels wires or connectors. Can transmit simultaneously.
Types of Bueses:

	Data Bus:
	Which Data transmitted. It is like a highway. Connects all components to CPU and main memory.	
	The siz(width) of bus determines how much data can be transmitted at one time. 16=16,32=32 easy
	
	Address Bus:
	Wires that identify particular location in main memory.
	Size determines how many unique memory locations can be addressed. for 4bit adressed=2*4=16bytes of memory
	
	Control Bus:
	Regulates the activity on the bus.Control bus carries signals that report the status of devices.
	Control signals transmit timing and command information among system modules.

	Typical Control Bus Signals:	
	Memory Read, placed data from the addressed location to data bus.
	Memory Write, writes the data on the bus to addressed location.
	I/O Read, causes data from the addressed I/O port to placed on the bus. 
	I/O Write, causes data on the bus to output, addressed I/O port.

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WEEK 4.1:

Interrupt Controller:

There are 5 interrupt signals:

TRAP Vector NON-Maskable. Highest priority. Enabled until acknowleged.
RST 7.5 Vector Maskable. 2nd Highest.
RST 6.5 Vector Maskable. 3rd Highest.
RST 5.5 Vector Maskable
INTR NON-Vector Maskable. Lowest priority. Can be disabled by resetting microprecessor.

TRAP is the only non-maskable interrupt in 8085.
TRAP is also automaticly vectored.

Vector interrupt, interrupt address is known.
NON-Vector, needs to send address externally.

Maskable interrupt, can be disabled by writing instructions.
NON-Maskable interrupt, CAN NOT disabled by writing instructions.

ISR: Interrupt Service Routine
El: one byte instruction, Enables using maskable interruptions.
DI: one byte instruction, Disables using maskable interruptions.

Can the microprecessor be interrupted again before comletion of ISR? (Multiple Interrupt?)
Only if we allow it to.
If El instruction placed early in the ISR, ıther interrupts MAY occur before ISR id done.

Branch Control Group
Branch is a control flow structure that allows a program to execute different sequences 
of instructions based on certain conditions.

JMP,Jump: program counter is loaded with given address, doesn't return.
CALL,Call: program counter saves the address and the next instruction's address. Return after execution.
RET,Return: Used at the end of a subroutine to return to the main program.

*Unconditional and conditional depends on corresponding flag condition.

*Fetch: The processor retrieves an instruction from the program memory. 
 This instruction is stored in a place called the Instruction Register.

Instruction Cycle: Total time required to execute an instruction.

Machine Cycle: There are, fetch, memory read/write, I/O read/write.
*First machine cycle is always an opcode fetch cycle.
8085 has minimum 1 (which is a fetch cyclye), maximum 5 machine cycles.

T-state: Subdivision of operations in one system clock period.
In 8085 requires 4T-states. Others, between 3-6.

Timig Diagram: Graphical represantation of execution of instructions.

*Microprocessor needs +5V power supply.


8085:

8-bit microprocessor.
Has 40 pins.
Can generate clock signals internally.

Interrupt Pins:
When microprocessor receives interrupt signal, it discontinues whatever it was executing.
It starts executing new program indicated by the interrupt signal.
Interrupt signals are generated by external peripheral devices.
After execution of the new program, microprocessor goes back to the previous program.

Adress Bus, 16-bit.
Data Bus, 8-bit.

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WEEK 5:

Addressing Modes of 8085:

To perform operation we have to give corresponding instructions the processor.
In each instruction thera are 3 things needs to specified:
Operation to be performed.
Adress source of data.
Adress of the destination of result.

Advantages of AddressinModes in 8085:
Versatility.
Efficient memory usage.
Easy to use.
Improved performance.

There are 5 addressing modes:
Direct Addressing
Register Addressing
Register Indirect Addressing
Immediate Addressing
Implicit Addressing

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WEEK 6:

Instruction set of 8085:

8085 has 246 instructions. Each is represented by 8-bit. 
These 8-bit binary values is called Op-Code or Instruction Byte.

There are 5 class of Instruction Set:

	Data Transfer Instruction:
	These instruction moves data between memory and register. Both ways. 
	Copies data. Data not modifies.
	
	Arithmetic Instruction:
	Addition, Substraction, --> 8-bit of numbers, 
	contents of register added to contents of accumulator. Result stored in accumulator.
	No two other 8-bit registers can be added/substracted directly.
	(If the result of substraction is negative, it stored as 2's comlement form)
	
	Increment, Decrement --> Can be increment or decrement by 1 directly. On any register or memory.

	Logical Instruction:
	AND, OR, XOR, --> Any 8-bit data, or the contents of register, 
	or memory location can logically have these. With the contents of accumulator. 
	The result is stored in accumulator.

	Rotate, --> Each bit in the accumulator can be shifted 
	either left or right to the next position.


	Compare, --> Any 8-bit data, or the contents of register, or memory location can be compared for:
		Equality
		Greater Than
		Less Than
    			with the contents of accumulator. The result is reflected in status flags.
	
	Complement --> The contents of accumulator can be complemented.
			Each 0 is replaced by 1 and each 1 is replaced by 0.
	
	
	Branching Instruction
	Control Instruction

to be continued...