68k
Categories: Microcomputer stubs | 68k microprocessors | Computer architecture
The Motorola 680x0/0x0/m68k/68k/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.
The 68k family built upon Motorola's 8/16-bit 68h series of processors.
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The 68k family members
- 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)
- Generation three (fully 32-bit)
- Generation four (fully 32-bit)
- Others
Main uses
The 68k line of processors have been used in a variety of systems, from Texas Instruments calculators up to critical control systems of the Space Shuttle. However, they have become most well-known as processors powering desktop computers such as the Macintosh, the Amiga, the Atari, and others.
Today, these desktop systems are either end-of-line (in case of the Amiga and the Atari), or are using different processors (such as is the case for the Macintosh). Since these desktops are now more than a decade old, the original manufacturers either are out of business, or no longer provide an operating system for the hardware; however, the Debian and NetBSD operating systems are still supported for m68k processors.
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? Was there no -070?
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.
The next 68k generation
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.
Other variants
After the mainline 68k processors' demise, the 68k family has been used to some extent in microcontroller/embedded microprocessor versions. These chips include the ones listed under "other" above, i.e. the CPU32 (aka 68330), the ColdFire, and the DragonBall.
Competitors to the mainstream 68ks
The principal competitors in the microcomputer market for generation one were the x86 architecture 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 hitherto 68k marketplace was shifting over to the PowerPC, sounding the death knell for the 680x0 on the desktop.
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