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Motorola 68451
The MC68451 is a Motorola (now Freescale) Memory Management Unit (MMU), which was primarily used in conjunction with the Motorola MC68010 microprocessor. The MC68451 supported a 16 MB address space and provided a MC68000 or a MC68010 with support for memory management and protection of memory against unauthorized access. The block size was variable, so it was usually used for segment-based memory management. It supported the mapping of up to 32 memory segments or pages of a variable size from logical to physical addresses. To allow more segments or pages, the simultaneous use of multiple MC68451 MMUs was supported In combination with a MC68010, the MC68451 permitted the realization of virtual memory. With the earlier MC68000, this was not possible due to the way the MC68000 treated memory access errors, i.e. processor state could not always be properly restored after a page fault; two MC68000s would be required, with the main CPU pausing when it got a memory access error, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola
Motorola, Inc. () was an American Multinational corporation, multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011. Motorola Solutions is the legal successor to Motorola, Inc., as the reorganization was structured with Motorola Mobility being spun off. Motorola Mobility was acquired by Lenovo in 2014. Motorola designed and sold wireless network equipment such as cellular transmission base stations and signal amplifiers. Motorola's home and broadcast network products included set-top boxes, digital video recorders, and network equipment used to enable video broadcasting, computer telephony, and high-definition television. Its business and government customers consisted mainly of wireless voice and broadband systems (used to build private networks), and, public safety communicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freescale
Freescale Semiconductor, Inc. was an American semiconductor manufacturer. It was created by the divestiture of the Semiconductor Products Sector of Motorola in 2004. Freescale focused their integrated circuit products on the automotive, embedded and communications markets. It was bought by a private investor group in 2006, and subsequently merged into NXP Semiconductors in 2015. History As of 2003, Motorola Semiconductor Products Sector earned US$5.0 billion in semiconductor sales in 2002 (out of US$27 billion sales for all of Motorola). Motorola announced that their semiconductor division would be divested on October 6, 2003, to create Freescale. Freescale completed its Initial public offering (IPO) on July 16, 2004, at a price of US$13. In its announcement, it estimated the stock price to be US$17.50- 19.50 but following a cooling of the market towards tech stocks, it lowered its price to US$13. Existing shareholders of Motorola stock received 0.110415 shares of Freescale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Management Unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical addresses. An MMU effectively performs virtual memory management, handling at the same time memory protection, cache control, bus arbitration and, in simpler computer architectures (especially 8-bit systems), bank switching. Overview Modern MMUs typically divide the virtual address space (the range of addresses used by the processor) into pages, each having a size which is a power of 2, usually a few kilobytes, but they may be much larger. The bottom bits of the address (the offset within a page) are left unchanged. The upper address bits are the virtual page numbers. Page table entries Most MMUs use an in-memory table of items called a "page table", containing one "page table entry" (PTE) per page, to map virtual page numbers to ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola 68010
The Motorola MC68010 processor is a 16/32-bit microprocessor from Motorola, released in 1982 as the successor to the Motorola 68000. It fixes several small flaws in the 68000, and adds a few features. The 68010 is pin-compatible with the 68000, but is not 100% software compatible. Some of the differences were: * The MOVE from SR instruction is now privileged (it may only be executed in supervisor mode). This means that the 68010 meets Popek and Goldberg virtualization requirements. Because the 68000 offers an unprivileged MOVE from SR, it does not meet them. * The MOVE from CCR instruction was added to partially compensate for the removal of the user-mode MOVE from SR. * It can recover from bus faults, and re-run the last instruction, allowing it to implement virtual memory. * The exception stack frame is different. * It introduced a 22-bit Vector Base Register (VBR) that holds A 1:10of the 1 KiB-aligned base address for the exception vector table. The 68000 vector table was al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circuitry required to perform the functions of a computer's central processing unit. The integrated circuit is capable of interpreting and executing program instructions and performing arithmetic operations. The microprocessor is a multipurpose, clock-driven, register-based, digital integrated circuit that accepts binary data as input, processes it according to instructions stored in its memory, and provides results (also in binary form) as output. Microprocessors contain both combinational logic and sequential digital logic, and operate on numbers and symbols represented in the binary number system. The integration of a whole CPU onto a single or a few integrated circuits using Very-Large-Scale Integration (VLSI) greatly reduced the cost of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola 68451 Die
Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011. Motorola Solutions is the legal successor to Motorola, Inc., as the reorganization was structured with Motorola Mobility being spun off. Motorola Mobility was acquired by Lenovo in 2014. Motorola designed and sold wireless network equipment such as cellular transmission base stations and signal amplifiers. Motorola's home and broadcast network products included set-top boxes, digital video recorders, and network equipment used to enable video broadcasting, computer telephony, and high-definition television. Its business and government customers consisted mainly of wireless voice and broadband systems (used to build private networks), and, public safety communications systems like Astro an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motorola 68000
The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector. The design implements a 32-bit instruction set, with 32-bit registers and a 16-bit internal data bus. The address bus is 24 bits and does not use memory segmentation, which made it easier to program for. Internally, it uses a 16-bit data arithmetic logic unit (ALU) and two more 16-bit ALUs used mostly for addresses, and has a 16-bit external data bus. For this reason, Motorola termed it a 16/32-bit processor. As one of the first widely available processors with a 32-bit instruction set, and running at relatively high speeds for the era, the 68k was a popular design through the 1980s. It was widely used in a new generation of personal computers with graphical user interfaces, including the Macintosh 128K, Amiga, Atari ST, and X68000. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very large (main) memory". The computer's operating system, using a combination of hardware and software, maps memory addresses used by a program, called '' virtual addresses'', into ''physical addresses'' in computer memory. Main storage, as seen by a process or task, appears as a contiguous address space or collection of contiguous segments. The operating system manages virtual address spaces and the assignment of real memory to virtual memory. Address translation hardware in the CPU, often referred to as a memory management unit (MMU), automatically translates virtual addresses to physical addresses. Software within the operating system may extend these capabilities, utilizing, e.g., disk storage, to provide a virtual address space that ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNOS (operating System)
UNOS is the first, now discontinued, 32-bit Unix-like real-time operating system (RTOS) with real-time extensions. It was developed by Jeffery Goldberg, MS. who left Bell Labs after using Unix and became VP of engineering for Charles River Data Systems (CRDS), now defunct. UNOS was written to capitalize on the first 32-bit microprocessor, the Motorola Motorola 68000 series, 68k central processing unit (CPU). CRDS sold a UNOS based 68K system, and sold porting services and licenses to other manufacturers who had embedded CPUs. History Jeff Goldberg created an experimental OS using only eventcounts for synchronization, that allowed a preemptive kernel, for a Charles River Data Systems (CRDS) PDP-11. CRDS hired Goldberg to create UNOS and began selling it in 1981. UNOS was written for the Motorola 68000 series processors. While compatible with Version 7 Unix, it is also an RTOS. CRDS supported it on the company's Universe 68 computers, as did Motorola's Versabus systems. CRDS's prim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sun Microsystems
Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, the Network File System (NFS), and SPARC microprocessors. Sun contributed significantly to the evolution of several key computing technologies, among them Unix, RISC processors, thin client computing, and virtualized computing. Notable Sun acquisitions include Cray Business Systems Division, Storagetek, and ''Innotek GmbH'', creators of VirtualBox. Sun was founded on February 24, 1982. At its height, the Sun headquarters were in Santa Clara, California (part of Silicon Valley), on the former west campus of the Agnews Developmental Center. Sun products included computer servers and workstations built on its own RISC-based SPARC processor architecture, as well as on x86-based AMD Opteron and Intel Xeon processors. Sun also developed its own ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Technologies
Convergent Technologies was an American computer company formed by a small group of people who left Intel Corporation and Xerox PARC in 1979. Among the founders were CEO Allen Michels, VP Engineering Bob Garrow, head of marketing Kal Hubler, and operating system architect Ben Wegbreit. Convergent was primarily an OEM vendor with their computers resold by other manufacturers such as ADP, AT&T, Burroughs, Four-Phase Systems, Gould, Mohawk, Monroe Data Systems, NCR, and Prime. The company was purchased by Unisys in 1988. History The Distributed Systems division was responsible for the IWS, AWS, and NGEN. In 1982, Convergent formed the Data Systems division to focus on a multi-processor computer known as the MegaFrame, "the first system upgradable from super-minicomputer to mainframe". The division was headed by Ben Wegbreit and also responsible for the MiniFrame. Steve Blank, in charge of division marketing, went on to found several Silicon Valley startups, including E.piphany, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
