Uncategorized

ANALOG-TO-DIGITAL (ADC) AND DIGITAL-TO-ANALOG (DAC) CONVERTERS Analog-to-digital (ADC) and digital-to-analog (DAC) converters are used to interface the micro- processor to the analog world. Many events that are monitored and controlled by the micro- processor are analog events. These can range from monitoring all forms of events, even speech, to controlling motors and like devices. In […]
Continue reading…

16550 PROGRAMMABLE COMMUNICATIONS INTERFACE The National Semiconductor Corporation’s PC16550D is a programmable communications inter- face designed to connect to virtually any type of serial interface. The 16550 is a universal asynchronous receiver/transmitter (UART) that is fully compatible with the Intel microprocessors. The 16550 is capable of operating at 0–1.5 M baud. Baud rate is the […]
Continue reading…

8254 PROGRAMMABLE INTERVAL TIMER The 8254 programmable interval timer consists of three independent 16-bit programmable counters (timers). Each counter is capable of counting in binary or binary-coded decimal (BCD). The maximum allowable input frequency to any counter is 10 MHz. This device is useful wherever the microprocessor must control real time events. Some examples of […]
Continue reading…

THE PROGRAMMABLE PERIPHERAL INTERFACE The 82C55 programmable peripheral interface (PPI) is a very popular, low-cost interfacing component found in many applications. This is true even with all the programmable devices avail- able for simple applications. The PPI, which has 24 pins for I/O that are programmable in groups of 12 pins, has groups that operate […]
Continue reading…

I/O PORT ADDRESS DECODING I/O port address decoding is very similar to memory address decoding, especially for memory- mapped I/O devices. In fact, we do not discuss memory-mapped I/O decoding because it is treated the same as memory (except that the IORC and IOWC are not used because there is no IN or OUT instruction). […]
Continue reading…

BASIC I/O INTERFACE INTRODUCTION A microprocessor is great at solving problems, but if it can’t communicate with the outside world, it is of little worth. This chapter outlines some of the basic methods of communications, both serial and parallel, between humans or machines and the microprocessor. In this chapter, we first introduce the basic I/O […]
Continue reading…

QUESTIONS AND PROBLEMS 1. What types of connections are common to all memory devices? 2. List the number of words found in each memory device for the following numbers of address connections: (a) 8 (b) 11 (c) 12 (d) 13 (e) 20 3. List the number of data items stored in each of the following […]
Continue reading…

SUMMARY 1. All memory devices have address inputs; data inputs and outputs, or just outputs; a pin for selection; and one or more pins that control the operation of the memory. 2. Address connections on a memory component are used to select one of the memory locations within the device. Ten address pins have 1024 […]
Continue reading…

DYNAMIC RAM Because RAM memory is often very large, it requires many SRAM devices at a great cost or just a few DRAMs (dynamic RAMs) at a much reduced cost. The DRAM memory, as briefly dis- cussed in Section 10–1, is fairly complex because it requires address multiplexing and refreshing. Luckily, the integrated circuit manufacturers […]
Continue reading…

PENTIUM THROUGH CORE2 (64-BIT) MEMORY INTERFACE The Pentium through Core2 microprocessors (except for the P24T version of the Pentium) contain a 64-bit data bus, which requires either eight decoders (one per bank) or eight separate write signals. In most systems, separate write signals are used with this microprocessor when interfacing memory. Figure 10–36 illustrates the […]
Continue reading…