computer organization and archietecture CO COA 9-36

1. PRESENTED BY :
Jay Patel (130110107036)
Jay Majithia (130110107009)
Faculty :
Prof. Kinjal Joshi
Gujarat Technological
University
G.H Patel College of Engineering
and Technology
Department of Computer
Engineering
Computer Organization

2. Design of Control Unit

3. G H PATEL COLLEGE OF ENGINEERING AND TECHNOLOGY 3
Decoding of microoperation field
• The bit of the microinstruction are usually divided into
fields, with each field defining a distinct separate
function.
• This method reduces the size of microinstruction bit but
requires additional hardware external to control memory
• The nine bit of the microoperation operation are divided
into three subfield of three bit each
• The control memory output of each subfield must be
decoded to provide distinct microoperations.

4. G H PATEL COLLEGE OF ENGINEERING AND TECHNOLOGY 4
Decoding of microoperation fields

5. G H PATEL COLLEGE OF ENGINEERING AND TECHNOLOGY 5
Microprogram sequencer
• The basic component of a microprogrammed control unit
are the control memory and the circuit that selects the
next address. The address selection part is called
microprogram sequencer.
• The purpose of microprogram sequencer is to present an
address to control memory so that a microinstruction
may be read and executed. The choice of address source is
guided by next address information bit that sequencer
receives from present instruction.

6. G H PATEL COLLEGE OF ENGINEERING AND TECHNOLOGY 6
Microprogram Sequencer

7. G H PATEL COLLEGE OF ENGINEERING AND TECHNOLOGY 7
Truth table of input logic