Question 16.17: Use a 32 × 8 bipolar PROM to form the following functions: f......
Use a 32 \times 8 bipolar PROM to form the following functions:
\begin{aligned}& f_{1}=\Sigma m(0,2,5,6,8) \\& f_{2}=\Sigma m(4,5,6,8,9) \\& f_{3}=\Sigma m(6,7,8,10,13,17,22,23)\end{aligned}
Since we need only three outputs, we shall assign the output data bits as:
f_{1}=D_{0}, \quad f_{2}=D_{1} \quad \text { and } \quad f_{3}=D_{2}
The remaining output data bits will be left open. Next, make a list of all the locations of the PROM (Fig. 16.14).
Each minterm of the expressions represents its own address. Minterm m_{4}, for example represents the address 4 on the table. Next, where a minterm is present within an expression, place a 1 in the table corresponding to that bit. Expression f_{2}, for example, includes minterm 5 . Therefore, place a 1 in bit D_{1} of address 5. Where a minterm is not present in, place a 0 within the corresponding data word. Figure 16.14 shows the completed table and the resulting logic diagram.
