A computer installation has 1000k of main memory. The jobs arrive and finish in the following sequences.

 Job 1 requiring 200k arrives
 Job 2 requiring 350k arrives
 Job 3 requiring 300k arrives
 Job 1 finishes
 Job 4 requiring 120k arrives 
 Job 5 requiring 150k arrives
 Job 6 requiring 80k arrives 

(a) Draw the memory allocation table using Best Fit and First fit algorithms.
(b) Which algorithm performs better for this sequence?

The capacity of a memory unit is defined by the number of words multiplied by the number of bits/word. How many separate address and data lines are needed for a memory of 4K × 16?

In a paged segmented scheme of memory management, the segment table itself must have a page table because

Consider a paging system that uses a 1-level page table residing in main memory and a TLB for address translation. Each main memory access takes 100 ns and TLB lookup takes 20 ns. Each page transfer to/from the disk takes 5000 ns. Assume that the TLB hit ratio is 95%, page fault rate is 10%. Assume that for 20% of the total page faults, a dirty page has to be written back to disk before the required page is read in from disk. TLB update time is negligible. The average memory access time in ns (round off to 1 decimal places) is ______.

Consider allocation of memory to a new process. Assume that none of the existing holes in the memory will exactly fit the process’s memory requirement. Hence, a new hole of smaller size will be created if allocation is made in any of the existing holes. Which one of the following statements is TRUE?

A certain moving arm disk storage, with one head, has the following specifications.

 Number of tracks/recording surface = 200
 Disk rotation speed = 2400 rpm
 Track storage capacity = 62,500 bits 

The average latency of this device is P msec and the data transfer rate is Q bits/sec.
Write the value of P and Q.

(a) The access times of the main memory and the Cache memory, in a computer system, are 500 n sec and 50 n sec, respectively. It is estimated that 80% of the main memory request are for read the rest for write. The hit ratio for the read access only is 0.9 and a write-through policy (where both main and cache memories are updated simultaneously) is used. Determine the average time of the main memory.
(b) Three devices A, B and C are corrected to the bus of a computer, input/output transfers for all three devices use interrupt control. Three interrupt request lines INTR₁, INTR₂ and INTR₃ are available with priority of INTR₁ > priority of INTR₂ > priority of INTR₃.
Draw a schematic of the priority logic, using an interrupt mask register, in which Priority of A > Priority of B > Priority of C.

A disk has 200 tracks (numbered 0 through 199). At a given time, it was servicing the request of reading data from track 120, and at the previous request, service was for track 90. The pending requests (in order of their arrival) are for track numbers

 30 70 115 130 110 80 20 25 

The storage area of a disk has innermost diameter of 10 cm and outermost diameter of 20 cm. The maximum storage density of the disk is 1400 bits/cm. The disk rotates at a speed of 4200 RPM. The main memory of a computer has 64-bit word length and 1µs cycle time. If cycle stealing is used for data transfer from the disk, the percentage of memory cycles stolen for transferring one word is

Consider a pipeline processor with 4 stages S1 to S4. We want to execute the following loop:
For(i=1:i<=1000; i++)
{I1,I2,I3,I4}
where the time taken (in ns) by instructions I1 to I4 for stages S1 to S4 are given below:

       S1   S2   S3   S4
I1:    1    2    1    2
I2:    2    1    2    1
I3:    1    1    2    1
I4:    2    1    2    1 

Which one of the following is NOT shared by the threads of the same process?

A disk has 8 equidistant tracks. The diameters of the innermost and outermost tracks are 1 cm and 8 cm respectively. The innermost track has a storage capacity of 10 MB.
If the disk has 20 sectors per track and is currently at the end of the 5^th sector of the inner-most track and the head can move at a speed of 10 meters/sec and it is rotating at constant angular velocity of 6000 RPM, how much time will it take to read 1 MB contiguous data starting from the sector 4 of the outer-most track?

A disk has 8 equidistant tracks. The diameters of the innermost and outermost tracks are 1 cm and 8 cm respectively. The innermost track has a storage capacity of 10 MB.
What is the total amount of data that can be stored on the disk if it is used with a drive that rotates it with (i) Constant Linear Velocity (ii) Constant Angular Velocity?

Consider a 2-way set associative cache memory with 4 sets and total 8 cache blocks (0-7) and a main memory with 128 blocks (0-127). What memory blocks will be present in the cache after the following sequence of memory block references if LRU policy is used for cache block replacement. Assuming that initially the cache did not have any memory block from the current job?

 0 5 3 9 7 0 16 55 

The memory access time is 1 nanosecond for a read operation with a hit in cache, 5 nanoseconds for a read operation with a miss in cache, 2 nanoseconds for a write operation with a hit in cache and 10 nanoseconds for a write operation with a miss in cache. Execution of a sequence of instructions involves 100 instruction fetch operations, 60 memory operand read operations and 40 memory operand write operations. The cache hit-ratio is 0.9.  The average memory access time (in nanoseconds) in executing the sequence of instructions is   __________.

Consider a paging hardware with a TLB. Assume that the entire page table and all the pages are in the physical memory. It takes 10 milliseconds to search the TLB and 80 milliseconds to access the physical memory. If the TLB hit ratio is 0.6, the effective memory access time (in milliseconds) is  _________.

Consider six memory partitions of sizes 200 KB, 400 KB, 600 KB, 500 KB, 300 KB and 250 KB, where KB refers to kilobyte. These partitions need to be allotted to four processes of sizes 357 KB, 210KB, 468 KB and 491 KB in that order. If the best fit algorithm is used, which partitions are NOT allotted to any process?

Assume that in a certain computer, the virtual addresses are 64 bits long and the physical addresses are 48 bits long. The memory is word addressable. The page size is 8 kB and the word size is 4 bytes. The Translation Look-aside Buffer (TLB) in the address translation path has 128 valid entries. At most how many distinct virtual addresses can be translated without any TLB miss?

Let the page fault service time to 10 ms in a computer with average memory access time being 20 ns. If one page fault is generated for every 10⁶ memory accesses, what is the effective access time for the memory?

A computer uses 46-bit virtual address, 32-bit physical address, and a three-level paged page table organization. The page table base register stores the base address of the first-level table (T₁), which occupies exactly one page. Each entry of T₁ stores the base address of a page of the second-level table (T₂). Each entry of T₂ stores the base address of a page of the third-level table (T₃). Each entry of T₃ stores a page table entry (PTE). The PTE is 32 bits in size. The processor used in the computer has a 1 MB 16-way set associative virtually indexed physically tagged cache. The cache block size is 64 bytes.

What is the size of a page in KB in this computer?

A computer uses 46-bit virtual address, 32-bit physical address, and a three-level paged page table organization. The page table base register stores the base address of the first-level table (T₁), which occupies exactly one page. Each entry of T₁ stores the base address of a page of the second-level table (T₂). Each entry of T₂ stores the base address of a page of the third-level table (T₃). Each entry of T₃ stores a page table entry (PTE). The PTE is 32 bits in size. The processor used in the computer has a 1 MB 16-way set associative virtually indexed physically tagged cache. The cache block size is 64 bytes.

What is the minimum number of page colours needed to guarantee that no two synonyms map to different sets in the processor cache of this computer?