Self doubt

Question

A micro programmed control unit uses one address instruction for control word sequencing. Based on the behaviour of control signals,the control signal field is divided into 6 groups. Each group contains  mutually exclusive control signals. The following table gives groupwise control signals. ( Group behavior : either one or none)

G1	G2	G3	G4	G5	G6
5	13	7	15	8	16

 

1. How many bits are saved in control field with respect to horizontal micro programming 
2. What is max degree of parallelism

Comments

i)64-21 ==> 43 bits are needed more when horizontal is used when compared to vertical microprogramming.

ii)I think 6

Answer 1

In Horizontal Micro programming we have control bit for each and every signal ...

so in horizontal we have one word of length=5+13+7+15+8+16.=64 bits

While in vertical Micro programming we uses decoder for each signal set

sp bits required are log(5)+log(13)+log(7)+log(15)+log(8)+log(16) that is

3+4+3+4+3+4=21 bits are required in vertical Micro programming

Bits saved = 64-21=43.

Max degree of parallelism = 64 signal which are generated in horizontal Micro programming