Textbook: \"Computer Organization & Architecture: Themes and Variations\" Author
ID: 3686140 • Letter: T
Question
Textbook: "Computer Organization & Architecture: Themes and Variations" Author: Alan Clements Publisher: Cengage Learning Edition: 1st ISBN: 978-1-111-98704-6
7.10. Why was microprogramming such a popular means of implementing control units in the 1980s
7.11. Why is microprogramming so unpopular today?
7.16. Derive an expression for the speedup ratio (i.e., the ratio of the execution time with pipelining) of a pipelined processor in terms of the number of stages in the pipeline m and the number of instructions to be executed N.
7.17. In what ways is the formula for the speedup of the pipeline derived in the previous flawed?
7.18. IF instruction fetch 300 ps
ID Instruction decode 150 ps
OF Operand fetch 250 ps
OE Execute 350 ps
M Memory access 700 ps
OS Operand store (writeback) 200 ps
a. What is the time to execute an instruction if the processor is not pipelined?
b. What is the time taken to fully execute an instruction assuming that this structure is pipelined in six stages and that there is an additional 20 ps per stage due to the pipeline latches?
c. Once the pipeline is full, what is the average instruction rate?
Explanation / Answer
It was able to emulate other computer systems
It was able to debug system using microdiagnostics
It was able for field modification without rewiring or board replacement
The basic problem for adoption of microprogramming was that a fast control memory was not available.
When the necessary memory was available, microprogramming was popular.
It was able to handle the difficulties associated with virtual memory, regarding restarting instructions after occuring of page faults.
Why is microprogramming so unpopular today?
Microprogram beleives in fast micromemory. It demands high speed memory.The early microprogrammed systems was depended on crucial technology, which was still in the development at that time. When the breakthrough in memory technology occured and S360 became the most successful family of computers. Hardwired control unit is very much faster. In contrary microprogramming is very low level, making it difficult to be 100% correct. Microprogramming is concurrent (many events occur at the same time), so it became hard for developing and debugging.
The ratio of the execution time with pipelining
T(m+(n-1))
where m=no. of stages in pipeline.
n= no. of instructions
T=clock period of the pipeline processor.
m clock periods are needed for completing the first task and remaining (n-1) tasks requires (n-1).
In what ways is the formula for the speedup of the pipeline derived in the previous flawed?
It was applied to there where the problem size was fixed. But as the problem size became large, the inherently serial work was time consuming. The parallelizable part often grows much faster than inherently serial work. So, formula for the speedup of the pipeline derived in the previous flawed?
What is the time to execute an instruction if the processor is not pipelined?
instruction latency is time from initiation of instruction to its completion each instruction consist of 6 stages
Instruction latency =300+150+250+350+700+200=1950
Time to execute 1 instruction is 1*instruction latency = 1950ns
Once the pipeline is full, what is the average instruction rate?
Once the pipeline is full, the processor can begin completing instructions twice as fast as the four-stage processor and eight times as fast as the single-stage processor.
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