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