A microprocessor is clocked at a rate of 5 GHz. How long is a clock cycle? What is the duration of a particular type of machine instruction consisting of three clock cycles? A microprocessor provides...

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1. A microprocessor is clocked at a rate of 5 GHz.
a. How long is a clock cycle? 2 x 10-10
Length = 1/5GHz = 20 nsec
b. What is the duration of a particular type of machine instruction consisting of three clock cycles?
Length = duration = 3* clock_length = 20 *3nsec = 60 nsec
6 x 10-10
2. A microprocessor provides an instruction capable of moving a string of bytes from one area of memory to another. The fetching and initial decoding of the instruction takes 10 clock cycles. Thereafter, it takes 15 clock cycles to transfer each byte. The microprocessor is clocked at a rate of 10 GHz.
a. Determine the length of the instruction cycle for the case of a string of 64 bytes.
Length of one clock cycle = 1/10GHz = 0.1 nsec
Length of instruction cycle = length of fetching and decoding + transfer of data
= [10 + 15*64] 0.1 ns
= 970 nsec
b. What is the worst-case delay for acknowledging an interrupt if the instruction is non-interruptible?
970 nsec
c. What is the worse-case delay for acknowledging an interrupt if the instruction can be interrupted at the beginning of each byte transfer?
In this case, the instruction can be interrupted after the instruction fetch, which takes 10 clock cycles, so the delay is 1 ns. The instruction can be interrupted between byte transfers, which results in a delay of no more than 15 clock cycles = 1.5 ns. Therefore, the worst-case delay is 1.5 ns.
3. Consider the timing diagram of Figure 12.10 in the 8th edition (or 14.10 in the 9th edition). Assume that there is only a two-stage pipeline (fetch, execute). Redraw the diagram to show how many time units are now required for four instructions.
    Instruction number
    Time
1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    Instruction
1
    FI
    DI
    
    
    
    
    
    
    
    
    Instruction
1
    
    CO
    FO
    
    
    
    
    
    
    
    Instruction
1
    
    
    EI
    WO
    
    
    
    
    
    
    Instruction
2
    
    
    
    FI
    DI
    
    
    
    
    
    Instruction
2
    
    
    
    
    CO
    FO
    
    
    
    
    Instruction
2
    
    
    
    
    
    EI
    WO
    
    
    
    Instruction
3
    
    
    
    
    
    
    FI
    DO
    
    
    Instruction
3
    
    
    
    
    
    
    
    CO
    FO
    
    Instruction
3
    
    
    
    
    
    
    
    
    EI
    WO
    Instruction number
    Time
11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    Instruction...