CH7 - Microprogrammed Control MICROPROGRAMMED CONTROL...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Microprogrammed Control MICROPROGRAMMED CONTROL Control Memory Sequencing Microinstructions Microprogram Example Microinstruction Format Design of Control Unit
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Microprogrammed Control COMPARISON OF CONTROL UNIT IMPLEMENTATIONS Implementation of Control Unit Control Unit Implementation Combinational Logic Circuits (Hardwired) I R Status F/Fs Combinational Logic Circuits Control Signals Memory Timing State Ins. Cycle State Control Unit's State Microprogrammed Status F/Fs Next Address Generation Logic C A R Control Memory ( -program) I R Decoder Control Signals Memory
Background image of page 2
3 Microprogrammed Control MICROPROGRAMMED CONTROL UNIT Control Memory - Storage in the microprogrammed control unit to store the microprogram Microprogram - Program stored in the control memory that generates all the control signals required to execute the instruction set correctly - Consists of microinstructions Microinstruction - Contains control word and next-address information - Control word : Specifies one or more microoperations to be executed - Next-address information : Information needed to decide the address of the microinstruction to be executed next Sequencer - Logic circuit that determines the address of the next microinstruction Control word Next address generator (sequencer) Control address register (CAR) Control memory (ROM) External input Next-address information Implementation of Control Unit
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Microprogrammed Control MICROINSTRUCTION SEQUENCING Fetch routine Indirect routine Execute routine Control Memory : : CAR - Microinstructions are stored in control memory in groups, each group specifies a routine - Each computer instruction has its own microprogram routine that generates the microoperations needed to execute the instruction - Address sequencing of control memory is capable of: - Sequencing the microinstructions within the routine - Branching from one routine to another based on the microinstruction Sequencing
Background image of page 4
5 Microprogrammed Control MICROINSTRUCTION SEQUENCING Sequencing Capabilities Required in a Control Memory - Incrementing of the control address register - Unconditional and conditional branches - A mapping process from the bits of the machine instruction to an address for control memory - A facility for subroutine call and return
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 17

CH7 - Microprogrammed Control MICROPROGRAMMED CONTROL...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online