Exam 2 Flashcards
What is a combinational circuit?
A circuit that depends only on the inputs for the result
What is a sequential circuit?
A circuit that depends on both the inputs and the previous result to get the result
What do the R and S inputs do in an SR latch?
S is Set and R is Reset
How does the D latch circuit work?
Controls when and how the latch can be/is updated; CLK controls when a latch is updated and D controls how a latch is updated
What is problematic about the SR latch?
Doesn’t differentiate between what and when something should happen
How does the D flip-flop work?
First latch acts as an airlock. Q is only updated on rising clock edges; state no longer updates continuously when CLK is enabled
What is an enabled flip-flop?
Flip-flop that can be turned on or off; gives us control over whether or not the flip-flop is updated on the clock pulse.
What is the role of registers on the CPU?
Registers hold commonly used operands
What is a computer’s “word size”?
bit size of each instruction
What is the word size for MIPS?
32 bits
How does a computer’s word size affect its design?
affects the max size of data the computer can address and process at once
What 4 circuit elements hold state in a MIPS single-cyle CPU?
Program Counter, Instruction Register, Register File, Data Memory
Describe the Program Counter
32 bit register that specifies the current instruction address and holds memory address of the next instruction
Describe the Instruction Memory
Stores the current program
Describe the Register File
Interface to the 32, 32 bit registers
