Unit 5 Flashcards
For every instruction, the first two steps are identical: Name them.
Send the program counter (PC) to the memory that contains the code and fetch the instruction from that memory.
Read one or two registers, using fields of the instruction to select the registers to read. For the LDUR and CBZ instructions, we need to read only one register, but most other instructions require reading two registers.
3rd step for memory-reference instructions
Use ALU for address calculation
3rd step for arithmetic-logic instructions
Use ALU for operation execution
Every instruction must first be fetched from memory, based on the value of the blank.
program counter
Every instruction reads one or two blank
registers
3rd step for branch instructions
use ALU for comparison
The blank stores the program that is to be executed.
instruction memory
The blank stores the data needed by the running programs.
data memory
The blank commands the datapath according to the instructions of the program by setting the control lines for each of the major functional units.
control unit
The blank elements include the instruction and data memories, the register file, the ALU, and adders.
datapath
An operational element, such as an AND gate or an ALU.
Combinational element
A memory element, such as a register or a memory.
State element
A blank element has at least two inputs and one output.
state
The elements that operate on data values are all blank, which means that their outputs depend only on the current inputs.
combinational
A sequential element is another name for a _____ element.
state
A clock input is present on a _____ element.
state
An ALU is a _____ element.
combinational
The approach used to determine when data is valid and stable relative to the clock.
Clocking methodology
A clocking scheme in which all state changes occur on a clock edge.
Edge-triggered clocking
A signal used for multiplexor selection or for directing the operation of a functional unit; contrasts with a data signal, which contains information that is operated on by a functional unit.
Control signal
The signal is logically high or true.
Asserted
The signal is logically low or false.
Deasserted
An blank allows us to read the contents of a register, send the value through some combinational logic, and write that register in the same clock cycle.
edge-triggered methodology
For the 64-bit LEGv8 architecture, nearly all of these state and logic elements will have inputs and outputs that are blank, since that is the width of most of the data handled by the processor
64 bits wide