Rtos (Real time operating system) is a piece of software that switches between tasks, giving the impression that multiple programs are being executed at the same time on a single processing core. In actual fact the processing core can only execute one program at any one time, and what the RTOS is actually doing is rapidly switching between individual programming threads (or Tasks) to give the impression that multiple programs are executing simultaneously. What is difference between OS and RTOS? The difference between an OS (Operating System) such as Windows/Linux and an RTOS (Real Time Operating System), is the response … Continue reading Introduction to Rtos (Real Time OS)

crt0 (also known as c0) is a set of execution startup routines linked into a C program that performs any initialization work required before calling the program’s main function. crt stands for C runtime. crt is a set of execution startup routines compiled into a program which performs any initialization work required before calling the program’s main function. It is a basic runtime library/system. The work performed by crt depends on the ABI, machine, compiler, operating system and C standard library implementation. The C Runtime system must carry out the following tasks. Set up the target platform in a consistent state. For example setting up appropriate exception … Continue reading The C Runtime Initialization

* Introduction Building a program from source code typically involves a few common steps: – Writing the source code – Process the code to expand all *#include* files, macros, etc. – Compiling the expanded source code to machine assembly language – Compiling assembly language to machine  binary code – Linking binary code in multiple files or libraries into   an executable binary program Executing these steps on a small set of source code may be manageable, but as the source code gets larger, the  process becomes more complex. * The Make System The *make* command looks for a file called … Continue reading Introduction of Make

8085 Microprocessor: The salient features of 8085 μp are : It is a 8 bit microprocessor. It is manufactured with N-MOS technology. It has 16 bit address bus and hence can address up-to 216 = 65536 bytes (64KB) memory locations through A0-A15. The first 8 lines of address bus and 8 lines of data-bus are multiplexed AD0 – AD7. Data bus is a group of 8 lines D0 – D7. It supports external interrupt request. A 16 bit program counter (PC). A 16 bit stack pointer (SP). Six 8-bit general purpose register arranged in pairs: BC,DE, HL. It requires a … Continue reading Micro Processor(x86 Basic)

Write a sample C program with errors for debugging purpose To learn C program debugging, let us create the following C program that calculates and prints the factorial of a number. However, this C program contains some errors in it for our debugging purpose. $ vim factorial.c # include <stdio.h> int main() { int i, num, j; printf (“Enter the number: “); scanf (“%d”, &num ); for (i=1; i<num; i++) j=j*i; printf(“The factorial of %d is %d\n”,num,j); } $ cc factorial.c $ ./a.out Enter the number: 3 The factorial of 3 is 12548672 Continue reading Introduction to gdb (Gnu Debugger)

=====> COMPILATION PROCESS <====== | |—-> Input is Source file(.c) | V +=================+ | | | C Preprocessor | | | +=================+ | | —> Pure C file ( comd:cc -E <file.name> ) | V +=================+ | | | Lexical Analyzer| | | +—————–+ | | | Syntax Analyzer | | | +—————–+ | | | Semantic Analyze| | | +—————–+ | | | Pre Optimization| | | +—————–+ | | | Code generation | | | +—————–+ | | | Post Optimize | | | +=================+ | |—> Assembly code (comd: cc -S <file.name> ) | V +=================+ | … Continue reading Compilation Process

C and Assembly: Many of us ( system/Embedded programmers) Who use C/Cpp for Firmware/Software Development is more comfortable writing in C/Cpp, and C is a mid-level language and Cpp being High-Level Language (in comparison to Assembly, which is a low-level language), and spares the programmers some of the details of the actual implementation. However, some of the low-level tasks can only be implemented in assembly (e.g. StartUp Code).Also, it is frequently useful for the programmer to look at the assembly output of the C compiler, and hand-edit or hand optimize the assembly code in ways that the compiler cannot. Assembly is also … Continue reading Mixed C and Assembly Programming (Embedded Systems)