Byte of the 8080 and the 8086, used in early personal computers, could also perform a small number of operations on the four-bit pairs in a byte, such as the decimal-add-adjust (DAA) instruction. A four-bit quantity is often called a nibble, also "nybble", which is conveniently represented by a single hexadecimal digit. The term "octet" is used to unambiguously specify a size of eight bits. It is used extensively in protocol definitions. Historically, the term "octad" or "octade" was used to denote eight bits as well at least in Western Europe; however, this usage is no longer common. The exact origin
Byte addressing be achieved in one instruction: store this character code at that byte address. Text programs are easier to write, smaller, and run faster. The advantage of word addressing is that more memory can be addressed in the same number of bits. The IBM 7094 has 15-bit addresses, so could address 32,768 words of 36 bits. The machines were often built with a full complement of addressable memory. Addressing 32,768 bytes of 6 bits would have been much less useful for scientific and engineering users. Or consider the 32-bit Pentium processor. Its 32-bit address bus can address 4 billion different items.