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Encyclopedia > Motorola 68020
Motorola 68020
Motorola 68020

The Motorola 68020 is a microprocessor from Motorola. It is the successor to the Motorola 68010 and is succeeded by the Motorola 68030. Download high resolution version (840x840, 165 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (840x840, 165 KB) Wikipedia does not have an article with this exact name. ... Microprocessors, including an Intel 80486DX2 and an Intel 80386 A microprocessor (sometimes abbreviated µP or uP) is a digital electronic component with miniaturized transistors on a single semiconductor integrated circuit (IC). ... Motorola NYSE: MOT is a global communications company based in Schaumburg, Illinois, a Chicago suburb. ... The Motorola MC68010 processor is a 16/32-bit microprocessor from Motorola, made in the early 1980s. ... Motorola 68030 Processor from a Macintosh IIsi The Motorola 68030 is a 32-bit microprocessor in Motorolas 68000 family. ...

Contents


Description

The 68020 had 32-bit internal and external data and address buses. A lower cost version, the 68EC020, only had a 24-bit address bus. 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ... The 68EC020 is a microprocessor from Motorola. ...


Improvements over 68010

The 68020 added many improvements to the 68010 including a 32-bit arithmetic and logical unit (ALU) and external data bus and address bus, and new instructions and addressing modes. The 68020 (and 68030) had a proper three-stage pipeline. ALU redirects here. ...


Multiprocessing features

The Motorola multiprocessing model was added with the 68020. This allowed up to eight processors per system to co-operate, these eight could be any number of CPUs, FPUs but a single MMU (either a 68841 or 68851). This had some limitation, as each CPU used had to be the same model (not necessarily the same clock) and each FPU has to be the same model (again, not necessarily the same clock) so multiprocessing a 68020/25 with a 68030/25 was not allowed (the 020, for example, could not be aware of the 030's internal MMU) but a 68020/25 with a 68882/33 was perfectly acceptable and quite common. It was, however, extremely uncommon to see more than one CPU or FPU in the same system. Most Unix boxes made with 68020s were simply the '020, an FPU (68881 or 68882) and an MMU (68841 or 68851). Wikibooks has more about this subject: Guide to UNIX Unix or UNIX is a computer operating system originally developed in the 1960s and 1970s by a group of AT&T Bell Labs employees including Ken Thompson, Dennis Ritchie, and Douglas McIlroy. ... The Motorola 68881 was a floating-point coprocessor chip that was utilized in some computer systems that used the 68020 or 68030 CPU. The addition of the 68881 chip added substantial cost to the computer, but added a floating point unit that could rapidly perform floating point math calculations. ... The Motorola 68881 was a floating-point coprocessor chip that was utilized in some computer systems that used the 68020 or 68030 CPU. The addition of the 68881 chip added substantial cost to the computer, but added a floating point unit that could rapidly perform floating point math calculations. ...


Instruction set

The new instructions included some minor improvements and extensions to the supervisor state, several instructions for software management of a multiprocessing system (which were removed in the 68060), some support for high-level languages which did not get used much (and was removed from future 680x0 processors), bigger (32 x 32-bit) multiply and divide instructions, and bit field manipulations.


Addressing modes

The new addressing modes added another level of indirection to many of the pre-existing modes, and added quite a bit of flexibility to various indexing modes and operations. Though it was not intended, these new modes made the 68020 very suitable for page printing; most laser printers in the early '90s had a 68EC020 at their core. In computer programming, indirection is the ability to reference something using a name, reference, or container instead of the value itself. ...


The instruction buffer (an instruction cache) was 256 bytes, arranged as 64 direct-mapped 4-byte entries. Although small, it made a significant difference in the performance of many applications.


Usage

The 68020 was used in many models of the Amiga and Apple Macintosh II series of personal computers and Sun 3 workstations. The Amiga is a family of home/personal computers originally developed by Amiga Corporation as an advanced game console. ... Apple Computer, Inc. ... Macintosh II was the first personal computer model of the Macintosh II series in the Apple Macintosh line. ...


For more information on the instructions and architecture see Motorola 68000. The Motorola 68000 is a CISC microprocessor, the first member of a successful family of microprocessors from Motorola, which were all mostly software compatible. ...


References

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.

The Free On-line Dictionary of Computing (FOLDOC) is an on-line, searchable encyclopedic dictionary of computing subjects. ... GNU logo The GNU Free Documentation License (GNU FDL or simply GFDL) is a copyleft license for free content, designed by the Free Software Foundation (FSF) for the GNU project. ...

External links

  • 68020 images and descriptions at cpu-collection.de


List of Motorola/Freescale microprocessors

The 6800 family | 6809 (see also: Hitachi 6309) | 68000 family: 68000 | 68008 | 68010 | 68012 | 68020 | 68030 | 68040 | 68060 | ColdFire | DragonBall | Pre-PPC RISC: 88000 | Floating-point coprocessors: 68881, 68882
PowerPC family (as part of AIM): PPC 7XX range (aka "PowerPC G3") | PPC 7XXX range (aka "PowerPC G4") Image File history File links The M-logo graphic of the Motorola logo, cropped from Image:Motologo. ... Image File history File links Logo graphic part of Freescale Semiconductor logo, cropped from Image:FreescaleSemiconductor. ... The following is a partial list of Motorola products, particularly the companys mobile phones and semiconductors. ... Motorola 6800 Microprocessor The 6800 is a microprocessor produced by Motorola and released shortly after the Intel 8080 in 1975. ... The Motorola 6809 is an 8-bit* microprocessor from Motorola, introduced circa 1979. ... The 6309 is Hitachis version of the Motorola 6809 microprocessor. ... 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 Motorola 68000 is a CISC microprocessor, the first member of a successful family of microprocessors from Motorola, which were all mostly software compatible. ... The Motorola MC68008 is a 8/16/32-bit microprocessor from the early 1980s. ... The Motorola MC68010 processor is a 16/32-bit microprocessor from Motorola, made in the early 1980s. ... The Motorola MC68012 processor is a 16/32-bit microprocessor from the early 1980s. ... Motorola 68030 Processor from a Macintosh IIsi The Motorola 68030 is a 32-bit microprocessor in Motorolas 68000 family. ... The Motorola 68040 is a microprocessor from Motorola. ... The Motorola 68060 is a 32-bit microprocessor from Motorola, and is the successor to the Motorola 68040. ... The Motorola Coldfire is a 68k architecture microprocessor manufactured for embedded systems development by Motorola (now Freescale Semiconductor). ... Motorola Dragonball Microprocessor Motorola/Freescale Semiconductors Dragonball is microprocessor design based on the famous 68000 core, but implemented as an all-in-one low-power solution for handheld computer use. ... The 88000 (m88k for short) is a microprocessor design produced by Motorola. ... The Motorola 68881 was a floating-point coprocessor chip that was utilized in some computer systems that used the 68020 or 68030 CPU. The addition of the 68881 chip added substantial cost to the computer, but added a floating point unit that could rapidly perform floating point math calculations. ... PowerPC is a RISC microprocessor architecture created by the 1991 Apple-IBM-Motorola alliance, known as AIM. Originally intended for personal computers, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... AIM was an alliance formed in 1991 between Apple Computer, IBM and Motorola to create a new computing standard based on the PowerPC architecture. ... PowerPC G3 is a designation used by Apple Computer to a third generation of PowerPC microprocessors. ... PowerPC G4 is a designation used by Apple Computer to describe a fourth generation of PowerPC microprocessors. ...


  Results from FactBites:
 
NationMaster - Encyclopedia: Motorola 68030 (1464 words)
Motorola 68020 The Motorola 68020 is a microprocessor from Motorola.
The Motorola 68040 is a microprocessor from Motorola.
A Motorola 68040 Microprocessor The Freescale 68040 is a microprocessor from Freescale, released in 1990.
NationMaster - Encyclopedia: Motorola 68020 (1189 words)
The Motorola 68020 is a microprocessor from Motorola.
Motorola 68030 Processor from a Macintosh IIsi The Motorola 68030 is a 32-bit microprocessor in Motorolas 68000 family.
The 68020 was used in many models of the Amiga and Apple Macintosh II series of personal computers and Sun 3 workstations.
  More results at FactBites »

 
 

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