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32-bit Dirty
Historically, the classic Mac OS used a form of memory management that has fallen out of favor in modern systems. Criticism of this approach was one of the key areas addressed by the change to . The original problem for the engineers of the Macintosh was how to make optimum use of the 128 KB of RAM with which the machine was equipped, on Motorola 68000-based computer hardware that did not support virtual memory. Since at that time the machine could only run one application program at a time, and there was no fixed secondary storage, the engineers implemented a simple scheme which worked well with those particular constraints. That design choice did not scale well with the development of the machine, creating various difficulties for both programmers and users. Fragmentation The primary concern of the original engineers appears to have been fragmentation – that is, the repeated allocation and deallocation of memory through pointers leading to many small isolated areas of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
About This Computer Mac OS 9
About may refer to: * About (surname) * About.com, an online source for original information and advice * about.me about.me is a personal web hosting service co-founded by Ryan Freitas, Tony Conrad and Tim Young in October 2009. The site offers registered users a simple platform from which to link multiple online identities, relevant external sites, and pop ..., a personal web hosting service * '' abOUT'', a Canadian LGBT online magazine * ''About Magazine'', a Texas-based digital platform covering LGBT news * About URI scheme, an internal URI scheme * About box, a dialog box that displays information related to a computer software * About equal sign, symbol used to indicate values are approximately equal See also * About Face (other) * About Last Night (other) * About Time (other) * About us (other) * About You (other) * '' about to'', one of the future constructions in English grammar * {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palm OS
Palm OS (also known as Garnet OS) was a mobile operating system initially developed by Palm, Inc., for personal digital assistants (PDAs) in 1996. Palm OS was designed for ease of use with a touchscreen-based graphical user interface. It is provided with a suite of basic applications for Personal information manager, personal information management. Later versions of the OS have been extended to support smartphones. Several other licensees List of Palm OS devices, have manufactured devices powered by Palm OS. Following Palm's purchase of the Palm trademark, the currently licensed version from Access Co., ACCESS was renamed ''Garnet OS''. In 2007, ACCESS introduced the successor to Garnet OS, called Access Linux Platform; additionally, in 2009, the main licensee of Palm OS, Palm, Inc., switched from Palm OS to webOS for their forthcoming devices. Creator and ownership Palm OS was originally developed under the direction of Jeff Hawkins at Palm, Inc., Palm Computing, Inc. Palm was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macintosh II
The Macintosh II is a personal computer designed, manufactured, and sold by Apple Computer from March 1987 to January 1990. Based on the Motorola 68020 32-bit CPU, it is the first Macintosh supporting color graphics. When introduced, a basic system with monitor and 20 MB hard drive cost . With a 13-inch color monitor and 8-bit display card the price was around . This placed it in competition with workstations from Silicon Graphics, Sun Microsystems, and Hewlett-Packard. The Macintosh II was the first computer in the Macintosh line without a built-in display; a monitor rested on top of the case like the IBM Personal Computer and Amiga 1000. It was designed by hardware engineers Michael Dhuey (computer) and Brian Berkeley (monitor) and industrial designer Hartmut Esslinger (case). Eighteen months after its introduction, the Macintosh II was updated with a more powerful CPU and sold as the Macintosh IIx. In early 1989, the more compact Macintosh IIcx was introduced at a price simi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macintosh 128K/512K Technical Details
The original Macintosh was a relatively simple machine, now of interest for its simplicity and for the fact that it was the first computer produced by Apple under the name Macintosh. The Macintosh used standard off-the-shelf components to the greatest extent possible, achieving a moderate price point by mixing complex LSI chips, readily customizable programmable array logic, and off-the-shelf components. Overall architecture The Macintosh used the Motorola 68000. The 68000's bus was wired directly to the other programmable components of the computer: the IWM floppy controller, the Zilog 8530 SCC, and the MOS Technology 6522. The bus also connected the 68000 to the 128 or 512 KiB of main memory (DRAM), which was shared between the processor and the multimedia circuits in a direct memory access (DMA) arrangement. Either the processor or the video/sound engine could access the memory, but not both, resulting in up to a 10% loss in performance; the DMA circuit also performed nece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Read-only Memory
Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing software that is rarely changed during the life of the system, also known as firmware. Software applications (like video games) for programmable devices can be distributed as plug-in cartridges containing ROM. Strictly speaking, ''read-only memory'' refers to memory that is hard-wired, such as diode matrix or a mask ROM integrated circuit (IC), which cannot be electronically changed after manufacture. Although discrete circuits can be altered in principle, through the addition of bodge wires and/or the removal or replacement of components, ICs cannot. Correction of errors, or updates to the software, require new devices to be manufactured and to replace the installed device. Floating-gate ROM semiconductor memory in the form of erasab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macintosh Plus
The Macintosh Plus computer is the third model in the Macintosh line, introduced on January 16, 1986, two years after the original Macintosh and a little more than a year after the Macintosh 512K, with a price tag of US$2,599. As an evolutionary improvement over the 512K, it shipped with 1 MB of RAM standard, expandable to 4 MB, and an external SCSI peripheral bus, among smaller improvements. Originally, the computer's case was the same beige color as the original Macintosh, Pantone 453; however, in 1987, the case color was changed to the long-lived, warm gray "Platinum" color. It is the earliest Macintosh model able to run System Software 5, System 6, and System 7. Overview Bruce Webster of ''BYTE'' reported a rumor in December 1985: "Supposedly, Apple will be releasing a Big Mac by the time this column sees print: said Mac will reportedly come with 1 megabyte of RAM ... the new 128K-byte ROM ... and a double-sided (800K bytes) disk drive, all in the standard Mac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macintosh 128k
The Apple Macintosh—later rebranded as the Macintosh 128K—is the original Apple Inc., Apple Macintosh personal computer. It played a pivotal role in establishing desktop publishing as a general office function. The motherboard, a CRT monitor, and a floppy drive were housed in a beige case with integrated carrying handle; it came with a keyboard and single-button mouse. It sold for . The Macintosh was introduced by a television commercial entitled "1984 (advertisement), 1984" shown during Super Bowl XVIII on January 22, 1984 and directed by Ridley Scott. Sales of the Macintosh were strong from its initial release on January 24, 1984, and reached 70,000 units on May 3, 1984. Upon the release of its successor, the Macintosh 512K, it was rebranded as the Macintosh 128K. The computer's model number was M0001. Development 1978–1984: Development In 1978 Apple began to organize the Apple Lisa project, aiming to build a next-generation machine similar to an advanced Apple II ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protected Memory
Memory protection is a way to control memory access rights on a computer, and is a part of most modern instruction set architectures and operating systems. The main purpose of memory protection is to prevent a process from accessing memory that has not been allocated to it. This prevents a bug or malware within a process from affecting other processes, or the operating system itself. Protection may encompass all accesses to a specified area of memory, write accesses, or attempts to execute the contents of the area. An attempt to access unauthorized memory results in a hardware fault, e.g., a segmentation fault, storage violation exception, generally causing abnormal termination of the offending process. Memory protection for computer security includes additional techniques such as address space layout randomization and executable space protection. Methods Segmentation Segmentation refers to dividing a computer's memory into segments. A reference to a memory location incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Connectix Virtual
Connectix Corporation was a software and hardware company, noted for having released innovative products that were either made obsolete as Apple Computer incorporated the ideas into system software, or were sold to other companies once they became popular. It was formed in October 1988 by Jon Garber; dominant board members and co-founders were Garber, Bonnie Fought (the two were later married), and close friend Roy McDonald. McDonald was still Chief Executive Officer and president when Connectix finally closed in August 2003. Products Primary products included these: * Virtual: Its original flagship product, which introduced virtual memory to the Macintosh operating system, Mac OS, years before Apple's implementation in System 7. Virtual also runs on a motley assortment of accelerator cards for the original Mac, Mac Plus, and Mac SE, which were not supported by Apple. * HandOff II: The file launcher developed by Fred Hollander of Utilitron, Inc. This INIT for Macintosh sol ... [...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] |
System 7
System 7, codenamed "Big Bang", and also known as Mac OS 7, is a graphical user interface-based operating system for Macintosh computers and is part of the classic Mac OS series of operating systems. It was introduced on May 13, 1991, by Apple Computer It succeeded System 6, and was the main Macintosh operating system until it was succeeded by Mac OS 8 in 1997. Current for more than six years, System 7 was the longest-lived major version series of the classic Macintosh operating system (to date, only Mac OS X had a longer lifespan). Features added with the System 7 release included virtual memory, personal file sharing, QuickTime, QuickDraw 3D, and an improved user interface. With the release of version 7.6 in 1997, Apple officially renamed the operating system "Mac OS", a name that had first appeared on System 7.5.1's boot screen. System 7 was developed for Macs that used the Motorola 680x0 line of processors, but was ported to the PowerPC after Apple adopted the new processor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MultiFinder
MultiFinder is an extension for the Apple Macintosh's classic Mac OS, introduced on August 11, 1987 and included with System Software 5. It adds cooperative multitasking of several applications at once – a great improvement over the previous Macintosh systems, which can only run one application at a time. With the advent of System 7, MultiFinder became a standard integrated part of the operating system and remained until the introduction of Mac OS X. History Background The first Macintosh was released in 1984, and Apple's developers made an early decision that the machine's 128 KB of RAM was so limited that they must abandon the application multitasking functionality that Apple had developed for the Lisa. As the successive Macintosh hardware models were released with much more RAM being the key feature, new programming techniques were developed as workarounds to allow users to run concurrent applications. Desk Accessories became a staple through the lifespan of System 6; a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
