Final answer:
To create a 1x8 demultiplexer, the 74HC238 3-to-8 line decoder can be utilized without internal modifications, by adjusting the input labels and connecting enable inputs properly. The data signal inputs into E1 (renamed D), and select lines A, B, and C are renamed as S0, S1, and S2.
Step-by-step explanation:
To implement the functionality of a 1x8 demultiplexer using an off-the-shelf MSI/LSI combinational logic IC, one potential approach is to use a 3-to-8 line decoder with enable inputs. The most commonly available IC for this purpose is the 74HC238. This IC is a 3-to-8 line decoder which has 3 binary select inputs (A, B, C) that can be used to demultiplex a single input into one of the eight outputs.
To use the 74HC238 as a 1x8 demultiplexer, no internal modifications to the IC are required. Instead, the IC's enable inputs (E1, E1, and E2) must be appropriately wired. In the demultiplexer application, the single input signal is to be connected to the E1 enable input (which should be relabeled as the data input D), while E2 is tied to logic low (0) and &2 bar is tied to logic high (1) ensuring that the decoder is active. The select inputs of the decoder (A, B, C) are relabeled as the select inputs S0, S1, S2 respectively.
Circuit mapping would then be as follows:
- Data input D (formerly E1) is the single input signal to be demultiplexed.
- Select inputs S0, S1, and S2 (formerly A, B, and C) will determine which one of the eight outputs is active.
- The eight outputs (Y0 to Y7) remain as they are, each corresponding to one of the demultiplexer outputs.
This configuration essentially alters the use of the 74HC238 from a simple decoder to a demultiplexer.