• • • • • • • • • • • • • • • • • • • • • • • • UNIT I Microcomputer: The term microcomputer is generally synonymous with personal computer, or a computer that depends on a microprocessor. Microcomputers are designed to be used by individuals, whether in the form of PCs, workstations or notebook computers. A microcomputer contains a CPU on a microchip (the microprocessor), a memory system (typically ROM and RAM), a bus system and I/O ports, typically housed in a motherboard. Microprocessor: A silicon chip that contains a CPU. In the world of personal computers, the terms microprocessor and CPU are used interchangeably. A microprocessor (sometimes abbreviated µP) is a digital electronic component with miniaturized transistors on a single semiconductor integrated circuit (IC). One or more microprocessors typically serve as a central processing unit (CPU) in a computer system or handheld device. Microprocessors made possible the advent of the microcomputer. At the heart of all personal computers and most working stations sits a microprocessor. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles. Three basic characteristics differentiate microprocessors: Instruction set: The set of instructions that the microprocessor can execute. Bandwidth: The number of bits processed in a single instruction. Clock speed: Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute. In both cases, the higher the value, the more powerful the CPU. For example, a 32 bit microprocessor that runs at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHz. In addition to bandwidth and clock speed, microprocessors are classified as being either RISC (reduced instruction set computer) or CISC (complex instruction set computer). Supercomputer: A supercomputer is a computer that performs at or near the currently highest operational rate for computers. A supercomputer is typically used for scientific and engineering applications that must handle very large databases or do a great amount of computation (or both). At any given time, there are usually a few well-publicized supercomputers that operate at the very latest and always incredible speeds. The term is also sometimes applied to far slower (but still impressively fast) computers. Most supercomputers are really multiple computers that perform parallel processing. In general, there are two parallel processing approaches: symmetric multiprocessing (SMP) and massively parallel processing (MPP). Microcontroller: A highly integrated chip that contains all the components comprising a controller. Typically this includes a CPU, RAM, some form of ROM, I/O ports, and timers. Unlike a general-purpose computer, which also includes all of these components, a microcontroller is designed for a very specific task - to control a particular system. A microcontroller differs from a microprocessor, which is a general-purpose chip that is used to create a multi-function computer or device and requires multiple chips to handle various tasks.
• • • • • • • • • • • • • • • • • • • • • • • • • A microcontroller is meant to be more self-contained and independent, and functions as a tiny, dedicated computer. The great advantage of microcontrollers, as opposed to using larger microprocessors, is that the parts-count and design costs of the item being controlled can be kept to a minimum. They are typically designed using CMOS (complementary metal oxide semiconductor) technology, an efficient fabrication technique that uses less power and is more immune to power spikes than other techniques. Microcontrollers are sometimes called embedded microcontrollers, which just means that they are part of an embedded system that is, one part of a larger device or system. Controller: A device that controls the transfer of data from a computer to a peripheral device and vice versa. For example, disk drives, display screens, keyboards and printers all require controllers. In personal computers, the controllers are often single chips. When you purchase a computer, it comes with all the necessary controllers for standard components, such as the display screen, keyboard, and disk drives. If you attach additional devices, however, you may need to insert new controllers that come on expansion boards. Controllers must be designed to communicate with the computer's expansion bus. There are three standard bus architectures for PCs - the AT bus, PCI (Peripheral Component Interconnect ) and SCSI. When you purchase a controller, therefore, you must ensure that it conforms to the bus architecture that your computer uses. Short for Peripheral Component Interconnect, a local bus standard developed by Intel Corporation. Most modern PCs include a PCI bus in addition to a more general IAS expansion bus. PCI is also used on newer versions of the Macintosh computer. PCI is a 64-bit bus, though it is usually implemented as a 32 bit bus. It can run at clock speeds of 33 or 66 MHz. At 32 bits and 33 MHz, it yields a throughput rate of 133 MBps. Short for small computer system interface, a parallel interface standard used by Apple Macintosh computers, PCs, and many UNIX systems for attaching peripheral devices to computers. Nearly all Apple Macintosh computers, excluding only the earliest Macs and the recent iMac, come with a SCSI port for attaching devices such as disk drives and printers. SCSI interfaces provide for faster data transmission rates (up to 80 megabytes per second) than standard serial and parallel ports. In addition, you can attach many devices to a single SCSI port, so that SCSI is really an I/O bus rather than simply an interface Although SCSI is an ANSI standard, there are many variations of it, so two SCSI interfaces may be incompatible. For example, SCSI supports several types of connectors. While SCSI has been the standard interface for Macintoshes, the iMac comes with IDE, a less expensive interface, in which the controller is integrated into the disk or CD-ROM drive. The following varieties of SCSI are currently implemented: SCSI-1: Uses an 8-bit bus, and supports data rates of 4 MBps.
• • • • • • • • • • • • SCSI-2: Same as SCSI-1, but uses a 50-pin connector instead of a 25-pin connector, and supports multiple devices. This is what most people mean when they refer to plain SCSI. Wide SCSI: Uses a wider cable (168 cable lines to 68 pins) to support 16-bit transfers. Fast SCSI: Uses an 8-bit bus, but doubles the clock rate to support data rates of 10 MBps. Fast Wide SCSI: Uses a 16-bit bus and supports data rates of 20 MBps. Ultra SCSI: Uses an 8-bit bus, and supports data rates of 20 MBps. Wide Ultra2 SCSI: Uses a 16-bit bus and supports data rates of 80 MBps. SCSI-3: Uses a 16-bit bus and supports data rates of 40 MBps. Also called Ultra Wide SCSI. Ultra2 SCSI: Uses an 8-bit bus and supports data rates of 40 MBps. Embedded system: A specialized computer system that is part of a larger system or machine. Typically, an embedded system is housed on a single microprocessor board with the programs stored in ROM. Virtually all appliances that have a digital Interface- watches, microwaves, VCRs, cars -utilize embedded systems. Some embedded systems include an operating system, but many are so specialized that the entire logic can be implemented as a single program. MICRO CONTROLLER MICRO PROCESSER • It is a single chip • Consists Memory, I/o ports • It is a CPU • Memory, I/O Ports to be connected externally CP CPU MEMORY I/O PORTS
8085 Microprocessor ContentsGeneral definitions Overview of 8085 microprocessor Overview of 8086 microprocessor Signals and pins of 8086 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 AD 0 – 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 signal +5V power supply and operates at 3.2 MHZ single phase clock. • It is enclosed with 40 pins DIP (Dual in line package). Overview of 8085 microprocessor 8085 Architecture • Pin Diagram •