Editing Intel iAPX 432 (section)

===Instruction format===
Executable instructions are contained within a system "instruction object".<ref name=GDPRef />{{rp|p.7-3}} Due to instructions being bit-aligned, a 16-bit ''bit'' displacement into the instruction object allows the object to contain up to 65,536 bits (8,192 bytes) of instructions.

Instructions consist of an ''operator'', consisting of a ''class'' and an ''opcode'', and zero to three ''operand references''. "The fields are organized to present information to the processor in the sequence required for decoding". More frequently used operators are encoded using fewer bits.<ref name=GDPRef />{{rp|p.7-6}} The instruction begins with the 4 or 6 bit class field which indicates the number of operands, called the ''order'' of the instruction, and the length of each operand. This is optionally followed by a 0 to 4 bit ''format'' field which describes the operands (if there are no operands the format is not present). Then come zero to three operands, as described by the format.  The instruction is terminated by the 0 to 5 bit opcode, if any (some classes contain only one instruction and therefore have no opcode). "The Format field permits the GDP to appear to the programmer as a zero-, one-, two-, or three-address architecture." The format field indicates that an operand is a data reference, or the top or next-to-top element of the operand stack.<ref name=GDPRef />{{rp|pp.7-3–7-5}}