Podcast
Questions and Answers
What is the purpose of the Call Instruction in a CPU?
What is the purpose of the Call Instruction in a CPU?
- Restores the register values from the stack
- Increments the program counter (PC) to the next instruction
- Loads the PC with the address of the entry point of the called line of code or subroutine (correct)
- Stores register values on the stack at the location pointed to by the SP
What does the RET Instruction do in a CPU?
What does the RET Instruction do in a CPU?
- Stores register values on the stack at the location pointed to by the SP
- Loads the PC with the address of the entry point of the called line of code or subroutine
- Loads the PC with the return address stored on the stack (correct)
- Increments the stack pointer to point to the new top of the stack
During a Call Instruction, where is the return address stored?
During a Call Instruction, where is the return address stored?
- PC
- SP (correct)
- CPU
- Memory
What is responsible for storing register values on the stack during a Call Instruction?
What is responsible for storing register values on the stack during a Call Instruction?
What action does the Call Instruction take regarding the stack pointer (SP)?
What action does the Call Instruction take regarding the stack pointer (SP)?
Which component does a RET Instruction primarily act upon?
Which component does a RET Instruction primarily act upon?
What does the mode bit in the Program Status Word (PSW) indicate?
What does the mode bit in the Program Status Word (PSW) indicate?
What type of interrupt is generated by external devices at unpredictable times?
What type of interrupt is generated by external devices at unpredictable times?
Which part of the operating system runs in kernel mode?
Which part of the operating system runs in kernel mode?
What does a clock interrupt signal to the OS?
What does a clock interrupt signal to the OS?
In the context of interrupts, what does an error condition typically indicate?
In the context of interrupts, what does an error condition typically indicate?
What can code running in kernel mode do that code running in user mode cannot?
What can code running in kernel mode do that code running in user mode cannot?
What function does a system call serve in relation to user programs and the OS?
What function does a system call serve in relation to user programs and the OS?
What do privileged instructions refer to in the context of execution modes?
What do privileged instructions refer to in the context of execution modes?
What does hardware support enforce between processes?
What does hardware support enforce between processes?
Which type of interrupt is caused by an exception when executing the current instruction?
Which type of interrupt is caused by an exception when executing the current instruction?
In what scenarios can code running in user mode be allowed to access memory?
In what scenarios can code running in user mode be allowed to access memory?
What does an I/O device interrupt typically inform the OS about?
What does an I/O device interrupt typically inform the OS about?
What component is responsible for enabling the operating system to control or monitor aspects of CPU function?
What component is responsible for enabling the operating system to control or monitor aspects of CPU function?
What is the purpose of the Program Counter (PC) in a CPU?
What is the purpose of the Program Counter (PC) in a CPU?
In the context of subroutines, what is the purpose of the Stack Pointer (SP)?
In the context of subroutines, what is the purpose of the Stack Pointer (SP)?
When running an instruction, what does the ALU primarily do?
When running an instruction, what does the ALU primarily do?
What is the purpose of subroutines in a computer program?
What is the purpose of subroutines in a computer program?
What makes up a stack frame in computing?
What makes up a stack frame in computing?
What is the purpose of executing a TRAP instruction to switch from user mode to kernel mode?
What is the purpose of executing a TRAP instruction to switch from user mode to kernel mode?
What does the systemcall handler do after examining the systemcall number?
What does the systemcall handler do after examining the systemcall number?
In the context of system calls, what does the %eax register store before invoking a system call?
In the context of system calls, what does the %eax register store before invoking a system call?
What is the role of the interrupt vector in handling system calls?
What is the role of the interrupt vector in handling system calls?
Why is executing an int 64 instruction important in implementing a system call like fork()?
Why is executing an int 64 instruction important in implementing a system call like fork()?
What happens after a system call has been completed by the systemcall handler?
What happens after a system call has been completed by the systemcall handler?
