68k

The Motorola 680x0, 0x0, m68k, or 68k family of CISC microprocessor CPU chips were 32-bit from the start, and were the primary competition for the Intel x86 family of chips.

This family of chips built upon the 68h series of chips, which were their forebears.

Contents

1 The 68k family 2 The architectural heritage 3 Where did the 68050 go? Whatever happened to the 68070? 4 What of the next generation of chips? 5 Competitors

The 68k family

• Generation one
  • Motorola 68000 a hybrid 16/32 bit chip
  • Motorola 68EC000
  • Motorola 68HC000
  • Motorola 68008 a hybrid 8/16/32 bit chip
  • Motorola 68010
  • Motorola 68012
• Generation two (fully 32-bit)
  • Motorola 68020
  • Motorola 68EC020
  • Motorola 68030
  • Motorola 68EC030
• Generation three (fully 32-bit)
  • Motorola 68040
  • Motorola 68EC040
  • Motorola 68LC040
• Generation four (fully 32-bit)
  • Motorola 68060
• Others
  • Motorola CPU32 (aka Motorola 68330)
  • Motorola Coldfire
  • Motorola Dragonball

The architectural heritage

People who are familiar with the PDP-11 or VAX usually feel comfortable with the 68000. With the exception of the split of general purpose registers into specialized data and address registers, the 68000 architecture is in many ways a 32-bit PDP-11.

Where did the 68050 go? Whatever happened to the 68070?

Note that there is no 68050, this is because the design that was destined to be the 68050 was eventually released as a version of the 68040. There is also no revision of the 68060, as Motorola was in the process of shifting away from the 68k and 88k processor lines into its new PowerPC business, so the 68070 was never developed. Had it been, it would have been a revised 68060.

What of the next generation of chips?

The 4th generation 68060 shared most of the features of the Intel P5 architecture of x86. Should Motorola have decided to stick with the 680x0 series it is very likely that the next processor (68080) would have resembled Intel's P6 architecture.

Competitors

The principal competitors in the microcomputer market for generation one were the P1 and P2 IA-16 chips (8088, 80286). For generation two, it was the P3 IA-32 chips (80386), and for generation three it was the P4 IA-32 chips (80486). Generation four did compete against the P5 IA-32 chips (Pentiums), but to a lesser extent, as much of the marketplace was shifting over to the PowerPC, sounding the death knell for the 680x0 on the desktop.