CS302 Midterm Solved Subjective with References by Moaaz

Q21. Draw function table of a half adder circuit? (2)

Answer: Page 135 Lec14

Q22. What is difference b/w BCD to decimal decoder and binary 4-to-16 bit decoder? (2)

Answer: (Page 163) Lec17

number.

Q23. Explain major use of decoder circuits? (3) Lec16

Answer: (Page 158) Decoders have two major uses in Computer Systems.

1. Selection of Peripheral Devices

Computers have different internal and external devices like the Hard Disk, CD Drive, Modem, Printer etc. Each of these different devices is selected by specifying different codes. A decoder similar to the Electronic Door Lock/Unlock circuit is used to uniquely select or deselect the appropriate devices.

2. Instruction Decoder

Computer programs are based on instructions which are decode by the Computer Hardware and implemented. These instruction codes are decoded by an Instruction Decoder to generate signals that control different logic circuits like the ALU and memory to perform these operations.

Q25. PALS comes in different configurations and are identified by a unique number, identify parts of this number? (5)

Answer: (Page 186) Lec19 PALs come in different configurations they are identified by unique number. The numbers begin with the prefix PAL followed by two digits that indicate the number of inputs followed by a letter L active-low, H active-high or P programmable polarity followed by a single or two digits that indicate the number of outputs. In addition to the standard number there may be suffixes which specify the speed, package type and temperature range

Q26. One of the ABEL entry methods uses logic equation. Explain at least two examples? (5)

Answer: (Page 201) Lec20 ABEL however is case sensitive, thus variable „A‟ is treated separately from variable „a‟. All ABEL equations must end with „;‟.

Examples:-

(a)

(b)

Solution

(a)X = A& !B & C # !A & !B & !C # A & B # !B & C; (b)Y = (!A # B # !C #D) & (A # B # C);

Q21. Draw the function table of 2-to-4 decoder (2 marks)

Answer: (Page 158) Lec16 A 2-to-4 Decoder is represented by the function table.

Input Output I1 I0 O0 O1 O2 O3

Function Table of a 2-to-4 Binary Decoder

Q24. Explain BCD to Decimal Decoder (3marks)

Answer: (Page 163) Lec17

number. Thus invalid BCD codes 1010, 1011, 1100, 1101, 1110 and 1111 applied at the input of the Decoder do not activate any of the ten outputs."

Q26. Explain 8-input Multiplexer with the help of circuit Diagram and Function Table. (5marks)

Answer: (Page 170) Lec18

Input Output C B A F 1C0 1C1 1C2 1C3 2C0 2C1 2C2 2C3