MSI Logic Circuits Questions

• Output 5 of a 74138 octal decoder is selected when it is enabled by a data input of:
• Which is the decimal number for the BCD number, 10110110?
• What type of device is shown in the given figure, and what inputs (A3,A2,A1,A0) are required to produce the output levels as shown?
• What is an important attribute of the conditional signal assignment statement?
• The IEEE/ANSI symbol for a decoder has the internal designation bcd/dec. This means the decoder is a:
• What VHDL techniques are used to describe a priority encoder?
• In an AHDL BCD to binary code converter, how is multiplication by 10 accomplished?
• Refer to the display multiplexer given below. The MSD display is blank, while the LSD seems to be OK. The input and output lines to the 74157 and 7449 are checked with a scope and can be seen changing levels. The A input on the 74139 also changes; however, the 0 output on the 74139 is always LOW and the 1 output is always HIGH. The B and EN inputs on the 74139 are always LOW. What could cause the problem and what should be done to correct it?
• For the input values (A0–A3, B0–B3, Data Select = 1) given for the circuit given below, what will be indicated on the displays?
• The circuit in Figure 9-8 is defective; data is not appearing on the output lines. A check with the scope shows data pulses on the serial data line and multiplex control lines, S0–S2; no parity error is indicated. A further check with a logic probe indicates that Vcc and ground appear to be present. What might be wrong with the circuit?
• The device that is an application of SOP logic is a multiplexer.
• A demultiplexer is a device that converts some code to a recognizable number or character.
• A demultiplexer takes an input and turns it into a binary number.
• When outputs a, b, c, d, and g of a 7447 BCD-to-seven-segment code converter are active, the number displayed is 5.
• ADHL does not offer a multiplication operator.
• A multiplexer is a device that converts some code into a recognizable number or character.
• A device that selects one of several inputs to be placed on the output is a multiplexer.
• A VARIABLE can be thought of as a piece of scrap paper used to write down some numbers that can be used later.
• A circuit that converts some binary code into a singular active output representing its numerical value is a comparator.
• A logic circuit that determines if one input is equal to another is called a comparator.