Be clear when you solve it ROM memory cells can be hold 0 or 1 and output a spec

Question

Be clear when you solve it

ROM memory cells can be hold 0 or 1 and output a specific string of 0's or 1's by reading is done with a specific input on the k-address lines (...shown as I0-I4 below). The can also be used as a "solution" or equivalent to some combinational logic functions....thus the ROM performs as a set of combinational logic. This is illustrated in Figure 3 below: FIGURE 3 In this illustration, the X means a connection has been made (kept in place). (All other lines without an X means they have been removed via "blowing the fuse" that originally linked all the wires). Where an X appears, a '1' would is seen by the OR gate. If you set up a 00011 as input to this unit (...I4 I3 I2 I1 I0 = 00011...) what value comes out of the OR gates? (Your answer should be in A7...thru...A0 bit order)

Explanation / Answer

I4I3I2I1I0=00011……………[(00011)2=(3)10]

Hence the output line no. 3 will be ON for 5 to 32 bit decoder and all other o/p will be 0.

Now o/p line 3 is connected to OR gates of A7, A5, A4, A1.

Now as per the truth table of OR gate ,even if one i/p is 1 the o/p will be 1 .

Hence A7=A5=A4=A1=1

As other i/ps are 0

A6=A3=A2=A0=0

Hence final answer A7A6A5A4A3A2A1A0=10110010

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