Hardwired and Micro-programmed Control Unit

To execute an instruction, the control unit of the CPU must generate the required control signal in the proper sequence. As for example, during the fetch phase, CPU has to generate PCout signal along with other required signal in the first clock pulse. In the second clock pulse CPU has to generate PCin signal along with other required signals. So, during fetch phase, the proper sequence for generating the signal to retrieve from and store to PC is PCout and PCin. There are two approaches used for generating the control signals in proper sequence as Hardwired Control unit and Micro-programmed control unit.
Hardwired Control Unit
http://cse.googlogy.com/computer-organization/hardwired-control-unit/
Micro-Programmed-control-unit Control Unit
http://cse.googlogy.com/computer-organization/micro-programmed-control-unit/

AttributesHardwired Control Micro-programmed Control
SpeedFastSlow
Cost of
Implementation
MoreCheaper
FlexibilityNot flexible, difficult to modify for new
instruction
Flexible, new instructions can
easily be added
Ability to Handle
Complex Instructions
DifficultEasier
DecodingComplexEasy
ApplicationsRISC MicroprocessorCISC Microprocessor
Instruction Set SizeSmallLarge
Control MemoryAbsentPresent
Chip Area RequiredLessMore
COMPARISON BETWEEN HARDWIRED AND MICRO-PROGRAMMED CONTROL UNIT

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