Module 13  Introduction to Number Systems and Logic
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11 to 110,
111 to 120,
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131 to 140,
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151 to 160,
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341 to 346, Index
Figure 336.  Integrated logic circuits: A. Shift register; B. Logic package. Q61. What are RTL, DTL, and TTL examples of? Q62. What type of logic family uses diodes in the input? Q63. What is the most common type of integrated circuit packaging found in military equipment? Q64. Circuits that can be interconnected without additional circuitry are known as.................. circuits. SUMMARY Now that you have completed this chapter, you should have a basic understanding of the more common special logic circuits. The following is a summary of the emphasized terms and points found in the "Special Logic Circuits" chapter. SPECIAL LOGIC CIRCUITS perform arithmetic and logic operations; input, output, store and transfer information; and provide proper timing for these operations. EXCLUSIVE OR (XOR) circuits produce a 1 output when ONLY one input is HIGH. Can be used as a quarter adder. 341
EXCLUSIVE NOR (XNOR) circuits produce a 1 output when all inputs are 0 and when more than 1 input is 1. QUARTER ADDER circuits produce the sum of two numbers but do not generate a carry. HALF ADDER circuits produce the sum of two numbers and generate a carry. FULL ADDER circuits add a carry to obtain the correct sum. PARALLEL ADDER circuits use full adders connected in parallel to accommodate the addition of multipledigit numbers. STANDARD SYMBOLS depict logic circuitry with blocks, showing only inputs and outputs. One block may contain many types of gates and circuits. SUBTRACTION in binary is accomplished by complementing and adding. FLIPFLOP are bistable multivibrators used for storage, timing, arithmetic operations, and transfer of information. RS FFs have the Q output of the FF HIGH in the set mode and LOW in the reset mode. 342
T (TOGGLE) FF_{S} change state with each pulse applied to the input. Each T FF will divide the input by 2. D FF is used to store data at a predetermined time. JK FF is the most versatile FF. JKs can perform the same functions as all the other FFs. CLOCKS are circuits that generate the timing and control signals for other operations. COUNTERS are used to count operations, quantities, or periods of time. They can be used to divide frequencies, to address information in storage, or as temporary storage. MODULUS of a counter is the total number of counts or stable states a counter may indicate. UP COUNTERS count from 0 to a predetermined number. DOWN COUNTERS count from a predetermined number to 0. RING COUNTERS are loop counters that may be used for timing operations. REGISTERS are used as temporary storage devices as well as for transfer of information. PARALLEL REGISTERS receive or transfer all bits of data simultaneously. SHIFT REGISTERS are used to perform serialtoparallel and paralleltoserial conversion and for scaling binary numbers. 343
SERIAL TRANSFER causes all bits of data to be transferred on a single line. PARALLEL TRANSFER has each data bit on its own line. SCALING of binary numbers means to increase or decrease the magnitude of a number by a power of 2. LOGIC FAMILIES are composed of logic circuits based on particular types of elements. ANSWERS TO QUESTIONS Q1. THROUGH Q64. A1. ⊕. A2. Low (0). A3. One or the other of the inputs must be HIGH, but not both at the same time. A4. Exclusive NOR (XNOR). A5. HIGH. A6. The half adder generates a carry. A7. Quarter adder. A8. Sum equals 0 with a carry of 1. A9. Full adder. A10. Four. A11. S_{1} = 1, S_{2} = 0 and C_{2} = 1. A12. C_{1} = 0. A13. XOR gates. A14. Four. A15. MSD of the sum. A16. Add 1 portion. A17. Subtrahend. A18. Storing information. A19. Six. A20. 1 and 0, or opposite states. A21. By crosscoupling NAND or OR gates. A22. One. 344
A23. To divide the input by 2. A24. Clock and data. A25. Up to one clock pulse. A26. A positivegoing clock pulse. A27. JK flipflop. A28. Set, or HIGH (1). A29. When the clock pulse goes LOW. A30. Both J and K must be HIGH. A31. Clear (CLR) and preset (PS or PR). A32. The flipflop is jammed. A33. A timing signal. A34. An astable or freerunning multivibrator. A35. Triggers. A36. A multiphase clock. A37. 32. A38. Ripple. A39. Toggle. A40. Synchronous. A41. The AND gate. A42. 1111_{2}, or 15_{10}. A43. Four. A44. FFs 2 and 4. A45. Two. A46. Three. A47. The input, or clock pulse. A48. One. A49. Four. A50. Q output of FF 1 going LOW. 345
A51. 16. A52. Parallel. A53. By clearing the register. A54. Shift register. A55. Serial. A56. Requires more circuitry. A57. Eight. A58. Four. A59. 2^{2}, or four times. A60. Three to the left. A61. Logic families. A62. DTL (diode transistor logic). A63. DIPs (dual inline packages). A64. Compatible. 346
NEETS Table of Contents
 Introduction to Matter, Energy,
and Direct Current
 Introduction to Alternating Current and Transformers
 Introduction to Circuit Protection,
Control, and Measurement
 Introduction to Electrical Conductors, Wiring
Techniques, and Schematic Reading
 Introduction to Generators and Motors
 Introduction to Electronic Emission, Tubes,
and Power Supplies
 Introduction to SolidState Devices and
Power Supplies
 Introduction to Amplifiers
 Introduction to WaveGeneration and WaveShaping
Circuits
 Introduction to Wave Propagation, Transmission
Lines, and Antennas
 Microwave Principles
 Modulation Principles
 Introduction to Number Systems and Logic Circuits
 Introduction to Microelectronics
 Principles of Synchros, Servos, and Gyros
 Introduction to Test Equipment
 RadioFrequency Communications Principles
 Radar Principles
 The Technician's Handbook, Master Glossary
 Test Methods and Practices
 Introduction to Digital Computers
 Magnetic Recording
 Introduction to Fiber Optics
