Posts by Farahat

Microcontroller Applications We have now looked at some of the main ideas to be used in explaining microcontroller operation: hardware, software, how they interact and how the function of complex systems can be represented using block diagrams and flowcharts. The microcontroller provides, in a simplified form, all the main elements of the microprocessor system on […]
Continue reading…

Execution Cycle Program execution is illustrated in Figure 1.7. Assuming that the application program code is in RAM, the program execution cycle proceeds as follows: 1. The CPU outputs (1) the address of the memory location containing the required instruction (this address is kept in the program counter). The sample address is shown in hexadecimal […]
Continue reading…

System Operation The CPU controls the system data transfers via the data and address buses and additional control lines. A clock circuit, usually containing a crystal oscillator (as found in digital watches), is required; this produces a precise fixed frequency signal that drives the microprocessor along. The CPU operations are triggered on the rising and […]
Continue reading…

Data Output Going back to the word processor, the characters must be displayed on the screen as they are typed in, so the character codes stored in memory are also sent to the screen via the graphics interface. The display is made up of single colored dots (pixels) organized in lines across the screen, which […]
Continue reading…

Microprocessor Systems All microprocessor systems perform the same essential functions, that is, data or signal input, storage, processing and output. However, the PC is a relatively complex microprocessor system, with a hierarchical bus structure, which has developed to improve system performance by alleviating the bus bottleneck of earlier designs. The Intel PC processor itself also […]
Continue reading…

Data Storage The character data is received by the CPU from the keyboard, or other interface, in parallel form, via the internal data bus. It is stored in a CPU register and then copied back to RAM. RAM locations are numbered and accessed via the system address bus, a set of lines that select a […]
Continue reading…

Starting the Application Windows displays an initial screen with icons and menus, which allow the application to be selected by clicking on a shortcut. Windows converts this action into an operating system command which runs the executable file (WINWORD.EXE, etc.) stored on disk. The application program is transferred from disk to RAM, or as much […]
Continue reading…

Word-Processor Operation In order to understand the operation of the PC microprocessor system, we will look at how the word-processor application uses the hardware and software resources. This will help us to understand the same basic processes that occur in microcontrollers. Starting the Computer When the PC is switched on, the RAM is empty. The […]
Continue reading…

PC Memory There are two principal types of memory in the PC system. The main memory block is RAM, where input data is stored before and after processing in the CPU. The operating system and application program are also copied to RAM from disk for execution, because access to data in RAM is faster. Unfortunately, […]
Continue reading…

PC Motherboard The main features of typical motherboards are shown in Figure 1.3. The heart of the system is the microprocessor, a single chip, or central processing unit (CPU). The CPU controls all the other system components, and must have access to a suitable program in memory before it can do anything useful. The blocks […]
Continue reading…