cs501 final term solved papers by moaaz.Simple conditional transferIn an easy conditional transfer, a condition is checked, and if it’s true, the register transfer takesplace. Formally, a conditional transfer is represented asCond: RD ← RS.
This means if the condition ‘Cond’ is true, the contents of the register named RS (the sourceregister) are copied to the register RD (the destination register). the subsequent figure shows howthe registers could also be interconnected to realize a conditional transfer. during this circuit, the output ofthe source register RS is connected to the input of the destination registers RD.
However, noticethat the transfer won’t happen unless the enable input of the destination register is activated.We may say that the ‘transfer’ is being controlled by the enable line (or the control signal). Now,we are ready to control the transfer by selectively enabling the control signal, through the utilization ofother combinational logic which will be the equivalent of our condition.
The condition is, generally, a Boolean expression, and during this example, the condition isequivalent to LRD =1.Two-way transfersIn the above example, only one-way transfer was possible, i.e., we could only copy the contentsof RS to RD if the condition was met. so as to be ready to achieve two-way transfers, we mustalso provide a path from the output of the register RD to input of register RS.
this may enable usto implementCond1: RD ← RSCond2: RS ← RDConnecting multiple registersWe have seen how two registers are often connected. However, during a computer we’d like to connectmore than simply two registers. so as to attach these registers, one may argue that a connectionbetween the input and output of every be provided.
This solution is shown for a scenario wherethere are 5 registers that require to be interconnected.We can see that during this solution, an m-bit register requires two connections of m-wires each.Hence five m-bit registers during a “point-to-point” scheme require 20 connections; each with mwires.
Generally, n registers during a point to point scheme require n (n-1) connections. it’s quiteobvious that this solution isn’t getting to scale well for an outsized number of registers, as is that the casein real machines. the answer to the present problem is that the use of a bus architecture, which is explainedin the subsequent sections.