The Motorola 68040 is a microprocessor from Motorola, released in 1990. A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated Motorola Inc ( is an American, multinational Fortune 100, Telecommunications company based in Schaumburg Illinois. Year 1990 ( MCMXC) was a Common year starting on Monday (link displays the 1990 Gregorian calendar) It is the successor to the 68030 and is followed by the 68060 (the 68050 project having been abandoned. The Motorola 68030 is a 32-bit Microprocessor in Motorola 's 68000 family. The Motorola 68060 is a 32-bit Microprocessor from Motorola, released in 1994, and is the successor to the Motorola 68040. ) In keeping with general Motorola naming, the 68040 is often referred to as simply the 040 (pronounced oh-forty). The stripped-down version of the 68040 that lacks the FPU is the 68LC040.
In Macintosh computers, the 68040 was found mainly in the high-end Quadras. Macintosh, commonly nicknamed Mac is a Brand name which covers several lines of Personal computers designed developed and marketed by Apple Inc The Macintosh Quadra series was Apple Computer 's product family of professional high-end Apple Macintosh Personal computers built using the Motorola The fastest 68040 processor was clocked at 40 MHz and it was only used in the Quadra 840AV. The more expensive models in the (short-lived) mid-high Centris also used the 68040, while the cheaper Centris and Performas used the 68LC040. Macintosh Centris was a set of three 1993 Macintosh models that were built around the Motorola 68LC040 and 68040 CPUs The Macintosh Performa series was Apple Computer 's Consumer product family of Apple Macintosh Personal computers from 1992 until 1997 when the The 68040 was also used in other personal computers such as the Amiga 4000, as well as a number of Workstations and later versions of the NeXT computers. A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated The Commodore Amiga 4000, or A4000, was the successor of the A2000 and A3000 computers A workstation, such as a Unix workstation, RISC workstation or Engineering workstation, is a high-end Microcomputer NeXT Computer Inc (later NeXT Software Inc) was an American Computer company headquartered in Redwood City, California that
The 68040 is the first 680x0 family member with an on-chip FPU (floating point unit). The Motorola 680x0 / m68k / 68k / 68K is a family of 32-bit CISC Microprocessor CPU chips and was the primary A floating point unit (FPU is a part of a Computer system specially designed to carry out operations on Floating point numbers It thus includes all of the functionality that previously required external chips, namely the FPU and MMU (which was added in the 030). A memory management unit ( MMU) sometimes called paged memory management unit ( PMMU) is a Computer hardware component responsible for handling It also has split instruction and data caches of 4 kilobytes each. A kilobyte (derived from the SI prefix Kilo -, meaning 1000 is a unit of Information or Computer storage equal to either 1024 It is fully pipelined, with six stages. Pipelining redirects here For HTTP pipelining see HTTP pipelining.
Unfortunately the '040 ran into the transistor budget limit early in design. While the MMU did not take many transistors (indeed, having it on the same die as the CPU actually saved on transistors) the FPU certainly did. Motorola's 68882 external FPU was known as a very high performance unit and Motorola did not wish to risk integrators using the "LC" version with a 68882 rather than the more profitable full "RC" unit. For information on Motorola's multiprocessing model with the 680x0 series, see Motorola 68020. The Motorola 68020 is a 32-bit Microprocessor from Motorola, released in 1984. The FPU in the 68040 was thus made incapable of IEEE transcendental functions, which had been supported by both the 68881 and 68882 and were used by the popular fractal generating software of the time and little else. A transcendental function is a function that does not satisfy a Polynomial equation whose Coefficients are themselves polynomials in contrast to an The Motorola floating point support package (FPSP) emulated these instructions in software under interrupt. As this was an exception handler, over-use of the transcendental functions caused severe performance penalties.
Heat was always a problem throughout the 68040's life. While it delivered over double the per-clock performance of the old-when-released 68030 the chip's complexity and power requirements came from a large die and large caches. This affected the scaling of the processor and it never made it past 40 MHz. A 50 MHz variant was planned, but scrapped. Proto-overclockers reported success using the then-hardcore heatsinks with fans. The 68040 had feature-parity with the Intel 80486 but outperformed it quite significantly on a clock for clock basis. The Intel 486, otherwise known as the 80486 i486 or just 486 was the first tightly pipelined X86 design However, the 80486 had the ability to be clocked significantly faster and it did not suffer from overheating problems.
Versions of the '040 were created for specific market segments, including the 68LC040 which removed the FPU, and the 68EC040 which removed both the FPU and MMU. Motorola had intended the EC variant for embedded use but embedded processors during the 68040's time needed nowhere near the power of the '040, so EC variants of the '020 and '030 continued to be common in designs.
Motorola produced several speed grades. The 16 MHz and 20 MHz parts were never qualified (XC designation) and used as prototyping samples. 25 and 33 MHz grades featured across the whole line, but the 40 MHz grade was only for the 'full' 68040. A planned 50 MHz grade was cancelled after it exceeded the thermal design envelope.
For more information on the instructions and architecture, see Motorola 68000. The Motorola 68000 is a 16/32-bit CISC Microprocessor core designed and marketed by Freescale Semiconductor (formerly Motorola Semiconductor
Bibliography
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 online searchable encyclopedic Dictionary of Computing subjects The GNU Free Documentation License ( GNU FDL or simply GFDL) is a Copyleft License for free documentation designed by the Free Software
Notes and references
External links
- MC68040 Product Summary Page
- MC68040V Third-Generation 32-Bit Low-Power Microprocessor (PDF)
- M68040 Microprocessors User's Manual (PDF)
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