ARM ARM Certification EN0-001 Questions & Answers

• Question 1:

  In an ARMv7-A system, the following C function calculates a simple checksum for an input data packet of variable length. The checksum is defined to be the sum of all of the 16-bit data items in the packet modulo 65536. The parameter data_items contains the number of 2-byte data items in the packet, and it cannot be zero by design.

  

  When using an ARM compiler, which TWO of the following optimizations could improve the performance of this code? (Choose two)

  A. Use a do/while loop instead of a for loop

  B. Change the type of sum to be an unsigned short

  C. Change the type of i to be an unsigned int

  D. Use signed variables instead of unsigned variables

  E. Declare sum as a global variable

  Correct Answer: AC

• Question 2:

  Using a Generic Interrupt Controller (GIC), when the interrupt handler writes to the End of Interrupt Register (ICCEOIR), which of the following state transitions might occur for that interrupt ID?

  A. Inactive to Active

  B. Pending to Active

  C. Active to Inactive

  D. Active to Pending

  Correct Answer: C

• Question 3:

  When using the ARM Compiler (armcc), which of the following possible keywords can be used to remove padding bytes from a structure?

  A. __package

  B. __packed

  C. __compact

  D. __compress

  Correct Answer: B

• Question 4:

  What is the maximum value of the immediate field in an ARM SVC instruction?

  A. 0x0

  B. 0xF

  C. 0xFF

  D. 0xFFFFFF

  Correct Answer: D

• Question 5:

  A development board is supplied with a Board Support Package (BSP) for a particular operating system. Which TWO of these items would you expect to find in the BSP? (Choose two)

  A. Power supply and electrical cables

  B. Debugging hardware and software solution

  C. System on chip peripheral driver source code

  D. Boundary scan protocol definition

  E. Boot code for board-specific devices

  Correct Answer: CE

• Question 6:

  If the performance of an application remains unchanged when the core clock speed of a Cortex-A9 processor is reduced, what can you deduce about the system?

  A. The Clocks Per Instruction (CPI) of the processor has increased

  B. The processor is NOT the limiting factor on performance

  C. Instruction cache utilization has improved

  D. The core has stopped carrying out speculative data memory accesses

  Correct Answer: B

• Question 7:

  An ARM Cortex-A9 multi-core system has two CPUs, C1 and C2, each with a corresponding data cache. The code running on C1 writes to a memory location M. and C1 updates its data cache, but not main memory. After that, C2 tries to read the contents of memory location M. Which of the following hardware can automatically (without software inteivention) ensure that C2 reads the updated contents of M?

  A. Snoop Control Unit

  B. Tightly Coupled Memory

  C. Level 2 Cache Controller

  D. Dynamic Memory Access Controller

  Correct Answer: A

• Question 8:

  The Cortex-A9 processor has 6 breakpoint units and 4 watchpoint units. What is the maximum number of breakpoints the debugger can set on code in ROM?

  A. 6

  B. 10

  C. 2

  D. The debugger can use the BKPT instruction to do this.

  Correct Answer: A

• Question 9:

  An advantage of removable flash memory over built-in flash memory is that:

  A. Storage can be easily replaced, for example to increase capacity.

  B. It is quicker to access, providing far greater bandwidth for read operations.

  C. It has a longer life, indicated by being rated for a higher number of write cycles.

  D. It takes up less physical space in a device, and does not require any space on the printed circuit board.

  Correct Answer: A

• Question 10:

  What side-effect could using a debugger to read memory contents have?

  A. The memory contents could be set to zero

  B. Some memory contents could be rewritten

  C. The processor MMU pagetables could be modified

  D. The processor cache could be cleaned or/and invalidated

  Correct Answer: D