ILLUSTRATIVE EXAMPLE 2: INTERFACING INPUT SWITCHES In this section, we will analyze the circuit used for interfacing eight DIP switches as shown in Figure 5.8. The circuit includes the 74LS138 3-to-8 decoder to decode the low-order bus and the tri-state octal buffer (74LS244) to interface the switches to the data bus. The port can be […]
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Posts by Farahat
INTERFACING INPUT DEVICES
5.3 INTERFACING INPUT DEVICES The interfacing of input devices is almost identical to that of interfacing output devices, but with some differences in bus signals and circuit components. In this discussion, we will assume that you are familiar with the basic concepts of interfacing (Section 5.1.3) and describe only the additional details. First, we examine […]
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ILLUSTRATIVE EXAMPLE 1: INTERFACING LEDS
5.2 ILLUSTRATIVE EXAMPLE 1: INTERFACING LEDS In this section, we will analyze an actual interfacing circuit with the port address 07H to display binary data at an LED port and a single digit at a seven-segment LED. A group of 8 LEDs will be used to indicate binary I s and Os and will be’ […]
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Basic Concepts in Interfacing Output Devices
5.1.3 Basic Concepts in Interfacing Output Devices The concepts in interfacing output devices are similar to those in interfacing memory. The steps can be listed as follows: 1. Decode the low-order address bus to generate a unique pulse corresponding to the port address on the bus; this is called the I/O address (I͞O͞A͞D͞R͞) pulse. 2. […]
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Interfacing I/O Devices
Interfacing I/O Devices The I/O (Input/Output) is the third component of a microprocessor-based system. I/O devices, such as keyboards and displays, are the ears and eyes of the MPUs; they are the communication channels to the "outside world." Data can enter or exit in groups of eight bits using the entire data bus; this is […]
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ASSIGNMENTS ON MEMORY INTERFACING
1. if a memory chip is organized in a 4096 x 1 format, specify the number of registers in the chip and the number of bits stored by each register. 2. if 16K x 1 memory chips are used in a memory design, how many chips are required to design 64K-byte memory? 3. Specify the […]
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SUMMARY OF MEMORY INTERFACING
To read from memory, the address of the register to be read from should be placed on the address lines; arid the Chip Enable C͞E and R͞D signals must be , asserted low to enable the Output buffer. To write into memory, die address of the register to be written into should be placed […]
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SOME QUESTIONS AND ANSWERS ON MEMORY INTERFACING
In the above discussion of memory interfacing, we focused on certain aspects of the communication process between the Z80 and memory. However, in order to avoid distraction from basic concepts, we did not address several important issues. Now we will attempt to answer those questions briefly or provide references for them : . . How […]
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TESTING AND TROUBLESHOOTING INTERFACING CIRCUITS
In the last section, we discussed how to design or interface .memory for a given address. The next step is to test and verify that we can store a byte at a memory location within the address range of the memory chip and read the byte. At this point, we need to make an assumption […]
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ILLUSTRATIVE EXAMPLE 2: INTERFACING STATIC RIW MEMORY
In this example, we will use the MOSTEK MK4802 memory chip to demonstrate both Read and Write operations. To simplify the discussion, we will use the same decoding circuit as in Figure 7, except the M͞S͞E͞L4 signal is used as the Chip Enable. This chip has 2K of memory; therefore, two address lines (A12 and […]
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