Microprocessors
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from the main memory and keeping track of the display position of the screen. One of the commonly
used programmable CRT controllers is Intel’s 8275H. It allows a simple interface to almost any raster
scan CRT display with minimum external hardware and software overheads. The number of display
characters per row and the number of character rows per frame are software programmable.
13.14.9 Floppy Disk Controller
The floppy disk controller is used for disk drive selection, head loading, the issue of read/write
commands, data separation and serial-to-parallel and parallel-to-serial conversion of data. Examples of
floppy disk controllers include Intel’s 82078, 82077 and 8272.
13.14.10 Clock Generator
The clock generator is a circuit that produces a timing signal for synchronization of the circuit’s
operation. Examples of clock generators used in microprocessor systems include 8284 and 82284.
8284 generates the system clock for the 8086 and 8088 processors. It requires a crystal or a TTL
signal source for producing clock waveforms. It provides local READY and MULTIBUS READY
synchronization.
82284 is a clock generator/driver that provides clock signals for the 80286 processor and support
components. It also contains logic to supply READY to the CPU from either asynchronous or
synchronous sources and synchronous RESET from an asynchronous input with hysteresis. The 82284
is packaged in 18-pin DIP and contains a crystal-controlled oscillator, an MOS clock generator, a
peripheral clock generator, multibus ready synchronization logic and system reset generation logic.
13.14.11 Octal Bus Transceiver
Bus transceivers are devices with a high-output drive capability for interconnection with data buses.
In a microprocessor-based system they provide an interface between the microprocessor bus and the
system data bus. 8286 is an eight-bit bipolar transceiver with a three-state output that is used in a wide
variety of buffering applications in microcomputer systems. It comes in a 20-pin DIP package.
Review Questions
1. Briefly describe the difference between a microprocessor and a microcomputer. What are the three
main constituents of a microprocessor and what is the basic function performed by each one of
them.
2. What are the different types of register found in a typical microprocessor? Briefly describe the
function of each one of them.
3. Distinguish between the following
(a) address bus and data bus;
(b) direct addressing mode and indirect addressing mode;
(c) programmable timer and clock generator;
(d) programmable interrupt controller and DMA controller;
(e) RISC and CISC microprocessors.
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from the main memory and keeping track of the display position of the screen. One of the commonly
used programmable CRT controllers is Intel’s 8275H. It allows a simple interface to almost any raster
scan CRT display with minimum external hardware and software overheads. The number of display
characters per row and the number of character rows per frame are software programmable.
13.14.9 Floppy Disk Controller
The floppy disk controller is used for disk drive selection, head loading, the issue of read/write
commands, data separation and serial-to-parallel and parallel-to-serial conversion of data. Examples of
floppy disk controllers include Intel’s 82078, 82077 and 8272.
13.14.10 Clock Generator
The clock generator is a circuit that produces a timing signal for synchronization of the circuit’s
operation. Examples of clock generators used in microprocessor systems include 8284 and 82284.
8284 generates the system clock for the 8086 and 8088 processors. It requires a crystal or a TTL
signal source for producing clock waveforms. It provides local READY and MULTIBUS READY
synchronization.
82284 is a clock generator/driver that provides clock signals for the 80286 processor and support
components. It also contains logic to supply READY to the CPU from either asynchronous or
synchronous sources and synchronous RESET from an asynchronous input with hysteresis. The 82284
is packaged in 18-pin DIP and contains a crystal-controlled oscillator, an MOS clock generator, a
peripheral clock generator, multibus ready synchronization logic and system reset generation logic.
13.14.11 Octal Bus Transceiver
Bus transceivers are devices with a high-output drive capability for interconnection with data buses.
In a microprocessor-based system they provide an interface between the microprocessor bus and the
system data bus. 8286 is an eight-bit bipolar transceiver with a three-state output that is used in a wide
variety of buffering applications in microcomputer systems. It comes in a 20-pin DIP package.
Review Questions
1. Briefly describe the difference between a microprocessor and a microcomputer. What are the three
main constituents of a microprocessor and what is the basic function performed by each one of
them.
2. What are the different types of register found in a typical microprocessor? Briefly describe the
function of each one of them.
3. Distinguish between the following
(a) address bus and data bus;
(b) direct addressing mode and indirect addressing mode;
(c) programmable timer and clock generator;
(d) programmable interrupt controller and DMA controller;
(e) RISC and CISC microprocessors.