The 68020 (MC68020) is a 32-bit microprocessor by Motorola, released in 1984 as successor of the 68000 and 68010. Amongst others, it was used in Apple Macintosh II personal computers, Sun-3 workstations, and advanced dedicated chess computers. 68020 has a 32-bit ALU, and like already the 68010 a "loop mode", considered a mini instruction cache. As further improvements, it has Coprocessor- and Multiprocessing support, an scaled indexing addressing mode with another level of indirection to many of the pre-existing modes, and some new instructions, 32×32→64 bits multiply and 64÷32→32 bits quotient and 32 bits remainder instructions, and bit field support, including a bit field find first one instruction (BFFFO), which actually performs an up to 32-bit Leading Zero Count [1].
Die shot of Motorola 68020 [2]

See also

• 68000
• 68030

Publications

• MOTOROLA M68000 FAMILY - Programmer’s Reference Manual (pdf)
• Clara I. Serrano (1985). Introducing the MC68020: Performance and flexibility improvement through redesigned hardware and software enhancements. Proceedings of the National Computer Conference, pdf

External Links

• Motorola 68020 from Wikipedia
• cpu-collection.de >> by Class >> 68020
• Motorola 68000 family from Wikipedia

References

1. ^ Bit Field Instructions
2. ^ Die shot of Motorola 68020 microprocessor (MC68020FE16E) by Pauli Rautakorpi, September 26, 2013, Wikimedia Commons

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