1.What is the average memory access time for the processor described below? The

Question

1.What is the average memory access time for the processor described below?

The memory system has a cache access time (including hit detection) of 1 clock cycle

The clock rate is 1 ns

The miss penalty is 25 clock cycles

1% of instructions are not found in the cache

5% of data references are not found in the case

15% of memory accesses are for data

Note:  Assume that the read and write penalties are the same; other write stalls can be ignored.

1.4 ns

25ns

2.Order the memory technologies starting with the fasted typical access time as 1 and the slowest typical access time as3

SRAM:

DRAM:

Magnetic Disk:

a 1

b 2

c 3

Explanation / Answer

Answer is as follows :

a)

For this first we calculate miss rate as follows :

( (instruction not found in cache x (1-memory access for data)) + (data reference not found x memory access)

(0.01 x (1-0.15) + 0.05 x 0.15 )

0.01 x 0.85 + 0.05 x 0.15 = 0.16

and for average memory access time (AMAT)

= Hit Time + Miss Rate x Miss Penalty

= 1 + 0.16 x 25 = 1.4 ns

So correct option is C i.e. 1.4 ns

b) We know that SRAM and DRAM are types of RAM so these both are faster than magnetic disk because it is secondry memroy. But between SRAM is more fast than DRAM.

So

SRAM : a (1)

DRAM : b (2)

Magnetic Disk : c (3)

if there is any query please ask in comments,,

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