UGC NET CSE | January 2017 | Part 3 | Question: 3

Question

The general configuration of the microprogrammed control unit  is given below:

What are blocks B and C in the diagram respectively?

• A. Block address register and cache memory
• B. Control address register and control memory
• C. Branch register and cache memory
• D. Control address register and random access memory

Answer 1

Ans should be  (2) Control address register and control memory

pls refer   http://logos.cs.uic.edu/366/notes/microprogrammed_control_supplement.pdf for detail

Answer 2

option 2 is correct one .....control address register is one which tells the address of that micro-programmed signals which has to be generated .......that all are present in CONTROL MEMOERY as "WORDS"...(just like binary bits)

say control address register is 10 bits means 2^10 entries are there in CONTROL MEMORY....now we can select any one word and gve it as output.....

the width of word in CONTROL MEMORY depends on type of micro-programmed control 

1)Horizontal (for every signal we use one seperte bit)

2)Vertical(for signals we can use decoder to reduce the number of bits required )

Answer 3

Ans is B)

The logic of the control unit is specified by a micro-program. A micro-program is also called firmware (midway between the hardware and the software). It consists of:

(a) One or more micro-operations to be executed; and

(b) The information about the micro-instruction to be executed next.

The micro-instructions are stored in the control memory. The address register for the control memory contains the address of the next instruction that is to be read. The control memory Buffer Register receives the micro-instruction that has been read. A micro-instruction execution primarily involves the generation of desired control signals and signals used to determine the next micro-instruction to be executed. The sequencing logic section loads the control memory address register. It also issues a read command to control memory.

The general configuration of a micro-programmed control unit is demonstrated:

So Block B is Control Address Register and Block C is Control Memory

for references: http://cssimplified.com/computer-organisation-and-assembly-language-programming/explain-the-operation-of-a-micro-programmed-control-unit-with-the-help-of-a-diagram-8m-jun2008

Answer 4

Ans: B