Computer Architecture - Question and answer - 5

21. What is a horizontal microcode and what is its disadvantage?
In the horizontal format, each control signal is represented by a single bit in the control word. Thus, if the design has 500 control signals, this will require 500 bits in each control word to store the control bits. In this format, the control store looks horizontal in shape since the control words are wide.
The disadvantage of the horizontal format is that the size of the control store is large. However, it has the advantage of speed of operation as the control signals will be ready as soon as the control word is fetched from the control store.

22. What is Data hazards ?
Data hazards occur when instructions that exhibit data dependence modify data in different stages of a pipeline. Ignoring potential data hazards can result in race conditions (also termed race hazards). There are three situations in which a data hazard can occur:
Read after write (RAW), a true dependency
Write after read (WAR), an anti-dependency
Write after write (WAW), an output dependency

23. What are some of the components of a microprocessor?
Control Unit.
I/O Units.
Arithmetic Logic Unit (ALU)
Registers.
Cache.

24. What are flip-flops?
A flip-flop or latch is a circuit that has two stable states and can be used to store state information – a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs.

25. What is the easiest way to determine cache locations in which to store memory blocks?
The simplest way to determine cache locations in which store Memory blocks is direct Mapping technique.

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