Group 1 Michael Bouizza Rolando Abreu Carlos De Cossio Ricardo Urena Michael Hernandez Robert Romano Sun Li Yang

 A computer executes a program  Fetch/execute cycle  Each cycle has a number of steps  Called micro-operations  Atomic operation of CPU

 Memory Address Register (MAR)  Memory Buffer Register (MBR)  Program Counter (PC)  Instruction Register (IR)

 Address of next instruction is in PC  Address (MAR) is placed on address bus  Control unit issues READ command  Result appears on data bus  Data from data bus copied into MBR  PC incremented by 1  Data (instruction) moved from MBR to IR  MBR is now free for further data fetches

 t1:MAR <- (PC)  t2:MBR <- (memory)  PC <- (PC) +1  t3:IR <- (MBR)  (tx = time unit/clock cycle) or  t1:MAR <- (PC)  t2:MBR <- (memory)  t3:PC <- (PC) +1  IR <- (MBR)

ADD R1, X

ISZ X - increment and skip if zero

BSA X - Branch and Save Address Address of instruction following BSA is saved in X Execution continues from X+1

 Each phase decomposed into sequence of elementary micro-operations  Such as fetch, indirect, and interrupt cycles.  Execute cycle  One sequence of micro-operations for each opcode Assume new 2-bit register  Instruction cycle code (ICC) designates which part of cycle processor is in ▪ 00: Fetch ▪ 01: Indirect ▪ 10: Execute ▪ 11: Interrupt

 Can take many forms, depending on the instruction located in the IR.  May Involve transferring data among registers, read/write from memory or I/O, and  This cycle may involve transferring data among registers, read or write from memory or I/O.

 Define basic elements of processor  Describe micro-operations processor performs  Determine functions control unit must perform

 ALU  Registers  Internal data paths  External data paths  Control Unit

 Transfer data between registers  Transfer data from register to external  Transfer data from external to register  Perform arithmetic or logical ops

 Sequencing  Causing the CPU to step through a series of micro- operations  Execution  Causing the performance of each micro-op

Electronic Signals that execute instructions  In CPU  Causes Data Transfer  Executes Instructions  In Control Bus  Sends instructions out to I/O devices Ex: Modem, Soundcard & Video card  Sends signals to Memory

 Serial ATA Raid Controller on PCI Express

 MAR to PC  Opens Communication Between PC and MAR  MBR to Memory Steps Listed:  Opens Communication Between MAR and Address Bus  Memory gets Read Control Signal  Communication open Between Data Bus and MBR

 Single internal bus  Gates used in order to move through the buss  Control Signals will send out electronics signals to guide the transfer of information from the external systems bus  Temporary storage in registers are used for the proper functionality of ALU

 The control unit inputs signals are a combination of:  Opcode Bits.  Other signals such as interrupts, or condition codes.  Timing info (T1 to Tn). These signals are essential for timing for proper sequencing through instruction cycles.

 Instruction register the part of the CPU’s control unit that stores the instruction currently being executed or decoded.  Op-code causes different control signals for each different instruction  Unique logic for each op-code  Decoder takes encoded input and produces single output  n binary inputs and 2 n outputs

 Clock  Repetitive sequence of pulses  Useful for measuring duration of micro-ops  Must be long enough to allow signal propagation  Different control signals at different times within instruction cycle  Need a counter with different control signals for t1, t2 etc.

 Complex sequencing & micro-operation logic  Difficult to design and test  Inflexible design  Difficult to add new instructions

 What are a micro operations ?  Why should you not read and write from the same register at the same time ?  what are the basic elements of a processor ?  what happens when interupts are enabled ?  Name 3 sub-cycles for the instruction cycles

 How many types of micro-operation?  What are the inputs of the control signals?  List modern I/O Devices  What sends an electronic signals that organizes various processor unit to execute an instruction ?  What are advantages of hardware implementation ?

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