Explore: Opcode Size

possible through opcode-level programming to deliberately arrange the resulting code so that two code paths share a common fragment of opcode sequences. These

instructions. On the processing architecture, a given instruction may specify: opcode (the instruction to be performed) e.g. add, copy, test any explicit operands:

ALU. The opcode size (its bus width) determines the maximum number of distinct operations the ALU can perform; for example, a four-bit opcode can specify

uses a mnemonic to represent, e.g., each low-level machine instruction or opcode, each directive, typically also each architectural register, flag, etc.

computing, an opcode prefix is a numeric value that alters the function of a following opcode. On some instruction set architectures multiple opcode prefixes

two classes: Pre-existing opcodes that needed new mnemonics for their 32-bit OperandSize variants (e.g. CWDE, LODSD) New opcodes that introduced new functionality

FIN = byte0 >> 7 opcode = byte0 & 0b1111 masked = byte1 >> 7 assert masked, "The client must mask all frames" # Payload size payload_size = byte1 & 0b111_1111

byte sizes and execution times. (Some of them actually perform memory read operations but then ignore the data.) In the 65C802/65C816, all 256 opcodes perform

Fetching the instruction opcodes from program memory well in advance is known as prefetching and it is served by using a prefetch input queue (PIQ). The

human-readable compared to raw machine code. Each machine code instruction is an opcode which, in assembly, is replaced with a mnemonic. Each mnemonic corresponds