Unit 3 Flashcards
idea that instructions and data of many types can be stored in memory as numbers and thus be easy to change
stored-program concept
natural unit of access in a computer, usually a group of 32 bits
word
natural unit of access in a computer, usually a group of 64 bits; corresponds to the size of a register in the LEGv8 architecture
doubleword
command that moves data between memory and registers
data transfer instruction
value used to delineate the location of a specific data element within a memory array
address
requirement that data be aligned in memory on natural boundaries
alignment restriction
rightmost bit in an LEGv8 doubleword
least significant bit
leftmost bit in an LEGv8 doubleword
most significant bit
when a number that is the proper result of operations cannot be represented by the rightmost hardware bits
overflow
signed number representation where a leading 0 indicates a positive number and a leading 1 indicates a negative number. The complement of a value is obtained by complementing each bit (0 → 1 or 1 → 0), and then adding one to the result
two’s complement
notation that represents the most negative value by 10 … 000two and the most positive value by 01 … 11two, leaving an equal number of negatives and positives but ending up with two zeros, one positive (00 … 00two) and one negative (11 … 11two). The term is also used to mean the inversion of every bit in a pattern: 0 to 1 and 1 to 0
one’s complement
form of representation of an instruction composed of fields of binary numbers
instruction format
The field that denotes the operation and format of an instruction
opcode
AND can apply a bit pattern to a set of bits to force 0s where there is a 0 in the bit pattern. Such a bit pattern in conjunction with AND is traditionally called a
mask
moves all the bits in a doubleword to the left or right, filling the emptied bits with 0s
shift
A sequence of instructions without branches (except possibly at the end) and without branch targets or branch labels (except possibly at the beginning)
basic block
table of addresses of alternative instruction sequences
branch table
data structure for spilling registers organized as a last-in- first-out queue
stack
A value denoting the location of the saved registers and local variables for a given procedure.
frame pointer
addressing regime in which the address is the sum of the program counter (PC) and a constant in the instruction.
PC-relative addressing
operand is at the memory location whose address is the sum of a register and a constant in the instruction
base addressing
systems program that places an object program in main memory so that it is ready to execute
loader
