How to Control Common Bus in Computer Architecture?

Computer ArchitectureComputer ScienceNetwork

A bus is a structure that handles the data transmission in a computer system or network. The common bus of 16-bit is controlled by the selection inputs S2, S1 , and, S0.

Each binary number is associated with a Boolean variable x1 through x7, corresponding to the gate structure that must be active to select the register or memory for the bus.

For example, when x1 = 1, the value of S2, S1 , and, S0 must be 001 and the output of AR will be selected for the bus.

The decimal number shown with each bus input indicates the binary equivalent that must be applied to the selection inputs. This is helpful while selecting the appropriate register.

The decimal number shown with each bus input indicates the binary equivalent that must be applied to the selection inputs. This is helpful while selecting the appropriate register.

The table shows the register that is to be chosen for the particular binary numbers of selection inputs.

InputsOutputsRegister to be selected for bus
X1X2X3X4X5X6X7S2S1S0
0000000000None
1111111000AR
0000000010PC
0000000010DR
0000000101AC
0000000101IR
0000010110TR
0000001111Memory

Each of the binary numbers is related with a Boolean variable x1 through x7 in the figure.

The encoder Boolean functions are as follows −

S0 = x1 + x3 + x5 + x7

S1 = x2 + x3 + x6 + x7

S1 = x4 + x5 + x6 + x7

The logic for each encoder input can be determined if control functions that place the corresponding register onto the bus, are found.

raja
Published on 24-Jul-2021 09:52:57
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