Final Exam Flashcards
What are the three key concepts of the von Neumann Architecture?
1) Data and instructions are stored in single read/write memory
2) memory is addressable by location, regardless of the data type
3) execution occurs in a sequential fashion
What is hardware?
The physical configuration and wiring of the computer.
What is software?
A sequence of code or instructions carried out by the hardware.
What are the two major components of the CPU?
The instruction interpreter and and a module for general-purpose arithmetic and logic functions.
What are the two registers internal to the CPU?
1) Memory address Register (MAR) (stores mem. add for next read/write)
2) Memory Buffer Register (MBR) contains data to be written / just received from memory
Where is the address of the next instruction to be fetched held?
The PC register
What does the V flag mean?
A signed overflow flag - set when an addition or subtraction results in signed overflow (i.e. overflow for certain container size)
What does the C flag mean?
The carry flag - reports unsigned overflow.
What does the N flag mean?
Negative flag - always the same as the most significant bit of the result (the sign bit)
What does the S flag mean?
The sign flag - indicates the expected sign of the result (as if overflow didnt occur)
When are the N and S flags different?
When overflow occurs they are opposites.
What does the Z flag mean?
The result of the last operation was zero.
What does the H flag mean?
The half-carry flag - is set when addition sets off a “carry” from the LS nybble to the MS nybble in a byte.
What is volatile memory?
Information that decays naturally or is lost when power is turned off
What is nonvolatile memory?
Information that does not need power to be retained, remains without deterioration. ex: magnetic surface memory
