The technique used to find the starting address of the service routine (commonly known as the interrupt address vector) varies from one microprocessor to another. With some microprocessors the manufactures define the fixed starting address for each interrupt. Other manufacturers use an indirect approach by defining fixed locations where the interrupt address vector is stored. Read More
Showing posts with label Microprocessor and Microcontrollers. Show all posts
Showing posts with label Microprocessor and Microcontrollers. Show all posts
The general characteristics of I/O are described effectively in this post. One communications with a microcomputer system via the I/O devices interfaced to it. The user can enter programs and data using the keyboard on a terminal and execute the programs to obtain results. Therefore the I/O devices connected to a microcomputer system provide an efficient means of communication between the computer and the outside world. In a typical microcomputer system the user gets involved with two types of I/O devices physical I/O and logical I/O. when the microcomputer has no operating system the user must work directly with physical I/O devices and perform details I/O design. Read More
The performance of a microcomputer system can be significantly improved by introducing a small expensive but fast memory between the microprocessor and main memory. This memory is called cache memory and this idea was first introduced in the IBM 360/85 computer. Later on this concept was also implemented in minicomputers such as PDP-11/70 with the advent of VLSI technology, the cache memory technique is gaining acceptance in the microprocessor world.
The relationship between the cache and main memory blocks is established using mapping techniques. Three widely used mapping techniques are
- Direct mapping
- Fully associative mapping
- Set associative mapping
In the direct mapping the main memory address is divided into two fields an index field and a tag field. The number of bits in the index field is equal to the number of address bits required to access the cache memory. There are two ways of writing into cache the write back and write through methods, in the write back method whenever the microprocessor writes some things into a cache word a thirty bit is assigned to the cache word.
A memory unit is an internal part of any microcomputer system and its primary purpose is to hold programs and data. In a board sense a microcomputer memory system can be logically divided into three groups.
- Processor Memory
- Primary or Main memory
- Secondary Memory
Processor memory refers to the microprocessor registers. These registers are used to hold temporary results when a computation is in progress. Also there is no speed disparity between these register and the microprocessor because they are fabricated using the same technology.
Primary or main memory is the storage area in which all programs are executed. The microprocessor can directly access only those items that are stored in primary memory.
Secondary memory refers to the storage medium comprising slow device such as magnetic tapes and disks. These devices are used to hold large data files and huge programs such as compilers and data base management systems which are not needed by the processor frequently. Secondary memory stores programs and data in excess of the main memory. There are two types of optical disks.
The commercial microprocessor fabricated using the MOS technology is normally contained in a single chip. The microprocessor is comprised of a register section, one or more ALUs and a control unit. Depending on the register section the microprocessor can 
be classified either as an accumulator based or a general purpose register based machine.
be classified either as an accumulator based or a general purpose register based machine.In an accumulator based microprocessor such as the Intel 8085 and Motorola 6809, one of the operands is assumed to be held in a special register called the accumulator. All arithmetic and logic operations are performed using this register as one of the data sources. The result after the operation is stored in the accumulator. Read More
The microcomputer contains a microprocessor, a memory unit and an input/output unit. These elements are explained in the following in detail. The system bus contains three buses. These are the address bus, the data bus and the control bus. These buses connect
the microprocessor to each of the memory and I/O elements so that information transfer between the microprocessor and any of other elements can take place.
the microprocessor to each of the memory and I/O elements so that information transfer between the microprocessor and any of other elements can take place.On the address bus information transfer normally takes place only in one direction from the microprocessor to the memory or I/O elements. Therefore this is called a unidirectional bus. This bus is usually 16 to 32 bits wide. The data bus is a bidirectional bus. This bus is normally 8, 16, or 32 bits wide.
Typical data types include signed and unsigned binary integers, binary coded decimal, American standard code for information interchange and floating point numbers. There are various types of data types in microprocessor. These are as follows, Unsigned and signed binary integers, BCD numbers, ASCII, Floating point numbers. Read More.
The Intel Corporation introduced the first microprocessor, the 4004- 4bits, in 1971. the 4004 evolved from a development effort while designing a calculator chip set. Soon after the 4004 appeared in the commercial market, three other microprocessors were introduced. These were the Rockwell International 4-bit PPS-4, the Intel 8-bit 8008, and the National Semiconductor 16-bit IMF-16. In the year 1973 the second generation computer came with MOS Technology like Motorola 6800and 6809, Intel 8085 and Zilog evolved. This 8 bit microprocessor fabricated using the NMOS technology. The third generation microprocessors were introduced in the year of 1978. These processors are 16 bits wide such as Intel 8086/80186/80286. These processors are designed with HMOS technology. Read More
were introduced. These were the Rockwell International 4-bit PPS-4, the Intel 8-bit 8008, and the National Semiconductor 16-bit IMF-16. In the year 1973 the second generation computer came with MOS Technology like Motorola 6800and 6809, Intel 8085 and Zilog evolved. This 8 bit microprocessor fabricated using the NMOS technology. The third generation microprocessors were introduced in the year of 1978. These processors are 16 bits wide such as Intel 8086/80186/80286. These processors are designed with HMOS technology. Read More Single chip microcomputers are also referred to as microcontrollers. The microcontrollers are typically used for dedicated applications such as automotive systems, home appliances and home entertainment systems. Typical microcontrollers therefore include on chip timers, A/D and D/A converters. Two popular microcontrollers are intel 875 and Motorola HC16. The 16- bit microcontrollers include more on chip ROM, RAM and I/O compared to the 8 bit microcontrollers.
