UBUNTU - CHANGING BOOT ORDER

well, i guess u won't be needing this because its simply amazing working on ubuntu. its got all the features which are the basic necessity of a common user. but, in case u want to change the order by any reason

follow these steps in the terminal of ubuntu.

gedit /etc/default/grub

GRUB_DEFAULT=0 //you need to edit this line and set it one number less than the OS u want to from from 1st
for example, centos is in 5th position while boot up then set GRUB_DEFAULT=4( the reason may be bcz the values are stored in an array and so, one less than actual place value)


after this u need to run a command

sudo update-grub // u need to know the root password before u execute this command.




cheers to the self-less work done by developers of ubuntu!

Processor embedded in an embedded system

Processor is the "heart" of the embedded system and a very important part of the embedded system.
The 2 essential parts of the processor are:
1. Control Unit(CU) : This part helps to fetch instructions from memory.

2. Execution Unit(EU) : This part will have units(ex.ALU), that will implement data transfer, data conversion operations from one part to another.

so a processor runs the fetch and execute cycles(similar to heart pump-in and pump out of blood).

There are different types of processors
1. GPP(General Purpose Processor), ex- microprocessor

2. ASIP(Application Specific Instruction-set Processor), ex - microcontroller

3. Single purpose processor , ex - pixel processor, encrypt/decryption engine

4. GPP or ASIP integrated into a VLSI circuit or FPGA core integrated with a VLSI chip.

5.ASSP (Apllication Specific System Processor)

When we build a system the following considerations about processor has to be in our mind :

- Instruction set (Arithmetic instruction format, Conditional Branch and Immediate format, Unconditional Jump format, Input and Output instruction format).

- Maximum bits in an operand ( 8-bit,16-bit etc ).

- Clock frequency(Hz).

- Ability of the processor to solve complex algorithms.

AN EXAMPLE FOR EMBEDDED SYSTEM

This is an Automatic Chocolate Vending Machine (ACVM), a simple example of an Embedded system.
The hardware & software components embedded in this system can be described easily with the help of the block diagram.We can picturise the block diagram and the real world example and frame the sequence of instances in which the components work.

EMBEDDED SYSTEM - BASICS

SYSTEM - An arrangement in which units are assembled in such a way that, the units work according to a plan or program.

EMBEDDED SYSTEM - Is a system in which the units, hardware and software are embedded in the system such a way that they are dedicated for a particular application or they are a part of a large system.

An embedded system contains 3 important components
1.Hardware - Power supply, reset circuits, processor, program memory, data memory, input and output device interfacing/driver circuits, serial communication ports, timers are some of the components of hardware.

2.Software - This performs a series of tasks or processes for the application.

3.RTOS(real time OS) - This supervises the application software that performs tasks on hardware components based on priorities of tasks of the system.

CHARACTERISTICS OF AN EMBEDDED SYSTEM

1. Real time & multirate operations is the way system works, react to events, interrupts and schedules the system functioning.

2. Complex algorithms.

3. Complex GUI(graphical user interfaces) and other interfaces.

4. Dedicated functions.

CONSTRAINTS WHEN BUILDING AN EMBEDDED SYSTEM

1. Available system memory
2. Available processor speed.
3. Control on power dissipation.