Describe the functions of each of the following parts of the keyboard entry circuit of Figure 9-16.

(a) OR gate

(b) 74147 encoder

(c) One-shot

(d) Flip-flops X, Y, Z

(e) Flip-flops Q₀ to Q₁₁

Figure 9-16

Transcribed Image Text:

Digit keys +5 V 1 k0 For switch bounce 1p DT OS Q Ō 20 ms Pull-up resistor for each input 74LS147 decimal- to-BCD encoder CLK K ā₂ MSB LSB CLR X X J CLK K CLR Y J PRE CLK K Z Z D D Lo To decoder/drivers and displays D Q₁0 CLK D Q11 CLK CLK CLK CLK CLK CLK CLK 3 F Q₂ Q₂ CLK ^ Q₂ BCD code for MSD Second MSD