What is a Pointer? “A pointer is a variable which contains the address in memory of another variable“. The unary or monadic operator & gives the “address of a variable”. The indirection or dereference operator * gives the “contents of an object pointed to by a pointer”. int var; // declaration of “Integer type” variable name var which will have some // address in memory int *ptr; // To declare a pointer to a variable do ptr = &var; // copying address of variable “var” into new variable “ptr” as I have shown in below example, // C program … Continue reading Pointer’s basic
Memory is internal storage areas in the computer system. just like Our Human Body store “our day to day incidents” inside Our brain. Computer/Mobile phone store information inside Memory. The term memory identifies data storage that comes in the form of Silicon-chip’s ( pen-drives, SD cards), and the word storage is used for memory that exists on tapes or Hard- disks. Moreover, the term memory is usually used as a shorthand for physical memory, which refers to the actual silicon-chips capable of holding data. Some computers also use virtual memory, which expands physical memory onto a hard disk. Every computer comes with a certain amount of physical memory, usually referred to … Continue reading Computer Memory and It’s Type?
Harvard architecture has separate data and instruction busses, allowing transfers to be performed simultaneously on both busses. A von Neumann architecture has only one bus which is used for both data transfers and instruction fetches. therefore data transfers and instruction fetches must be scheduled – they can not be performed at the same time. but It is possible to have two separate memory systems for a Harvard architecture. Following are the difference between harvard architecture and von-neumann architecture Harward Architecture Von Neumann Architecture The name is originated from “Harvard Mark I” a relay based old computer. It is named after the … Continue reading von Neumann architecture and Harvard architecture
What is RISC? A reduced instruction set computer is a computer which only uses simple commands that can be divided into several instructions which achieve low-level operation within a single CLOCK cycle, as its name proposes “Reduced Instruction Set”. Example: Apple iPod and Nintendo DS etc. What is CISC? A complex instruction set computer is a computer where single instructions can perform numerous low-level operations like a load from memory, an arithmetic operation, and a memory store or are accomplished by multi-step processes or addressing modes in single instructions, as its name proposes “Complex Instruction Set ”. Example:IBM 370/168, VAX … Continue reading RISC and CISC Architecture
What is Polling ? Polling the device usually means reading its status register every so often until the device’s status changes to indicate that it has completed the request. Polling means you won’t know when the data is ready, but you can get it when you are ready. You’ll have to tell your program how to wait for the data. Example : below mentioned code, also is similar example of Transmit data by using polling. In above code, This line : while( ! (USCSA & (1 << UDRE)) simply waits for the transmit buffer to be empty by checking the UDRE flag, before … Continue reading Interrupt and Polling
Endianness refers to the sequential order in which bytes are arranged into larger numerical values when stored in memory. Simple way to remember is “little endian, the least significant byte will go to lowest address index. and Vice versa. Little endian and big endian are two ways of storing multi byte/nibble data-types ( i.e. int, float, etc). in big endian machines, first byte of binary representation of the multi byte data-type is stored first. On the other hand, In little endian machines, last byte of binary representation of the multi byte data-type is stored first. Current architectures The Intel x86 and also … Continue reading Little Endian vs Big Endian
Normally, Micro -Controller’s / Micro -Processor’s use two methods to connect external devices: Memory Mapped I/O. I/O Mapped I/O (also, known as Port Mapped I/O). However, as far as the peripheral is concerned, both methods are really identical. Memory mapped I/O is mapped into the same address space as program memory and/or user memory, and is accessed in the same way. I/O mapped I/O uses a separate, dedicated address space and is accessed via a dedicated set of … Continue reading MEMORY-MAPPED I/O VS I/O-MAPPED I/O
Thanks for joining me! Good company in a journey makes the way seem shorter. — Izaak Walton Continue reading The Journey Begins