Noun
quadword (plural quadwords)
(computing) A numerical value of four times the magnitude of a word, thus 64 bits on a 16-bit architecture.
Data types In the Alpha architecture, a byte was defined as an 8-bit datum (octet), a word as a 16-bit datum, a longword as a 32-bit datum, a quadword as a 64-bit datum, and an octaword as a 128-bit datum. Source: Internet
The Multiply Longword and Multiply Quadword instructions write the least significant 32 or 64 bits of a 64- or 128-bit result to the destination register, respectively. Source: Internet
Since it is useful to obtain the most significant half, the Unsigned Multiply Quadword High (UMULH) instruction is provided. Source: Internet
The conditional move instructions test a register as a signed quadword to zero and move if the specified condition is true. Source: Internet