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The following chapter focuses on the instruction set for a generic microprocessor by presenting the different instruction families and extensions in this set.

1 1 In the context of a microprogrammed architecture (this will be covered in a future book by the author on microprocessors), it is sometimes called a macro-instruction to differentiate it from the micro-instruction, which is internal to the processor.

2 2 Although these fields exist, they cannot be documented or can only be documented partially, as for MC6800 from Motorola.

3 3 We can choose not to code the instruction (an uncoded instruction). This means that one bit is assigned to each of the possible operations. The gain lies in eliminating the logic of classic decoding and the corresponding stage in a pipelined architecture (this will be covered in a future book by the author on microprocessors). The immediate counterpart is an increase in its format.

4 4 VAX for Virtual Addressed eXtended.

5 5 For MicroController Unit, i.e. a microcontroller (cf. § V3-5.3).

6 6 The mini-computer PDP-8 for Programmable Data Processor from DEC introduced in 1965 used this term.

7 7 Vocabulary from DEC (1983).

8 8 Here this means an immediate value following the instruction code that will serve as the address.