In the Pong game, for example, we will use a decoder to show scores on the screen, using a BCD (binary coded decimal) to a 7 segment decoder. Checking the datasheet of the TTL chip 7448, in the logic diagram, we can see it is built solely of logic gates which we already covered. Interestingly, the output side is built by specific AND-OR-INVERT circuits, which are very versatile and will be covered later. Also, we can see that the chip has 4 inputs (A, B, C, D) and 7 outputs (a, b, c, d, e, f, g, h).
Further, the following figure shows how binary coded decimal input pattern activates different outputs.
(Source: referenced)
The outputs of the BCD to 7-segment decoder can be easily demonstrated using 7-segment displays, which use 7 LED diodes to draw a number, and many of them have an additional indicator for the decimal point. The only thing worth noticing is that it comes in two arrangements:
- common cathode – cathodes of all LED diodes are grounded together
- common anode – anodes of all LED diodes are joined together to a positive voltage source
References:
https://www.electronicshub.org/bcd-7-segment-led-display-decoder-circuit/
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