1. The Reverie Of Being Mac Os X
2. The Reverie Of Being Mac Os Catalina
3. The Reverie Of Being Mac Os Download
4. The Reverie Of Being Mac Os 11

Mac OS, operating system (OS) developed by the American computer company Apple Inc. The OS was introduced in 1984 to run the company’s Macintosh line of personal computers (PCs). The Macintosh heralded the era of graphical user interface (GUI) systems, and it inspired Microsoft Corporation to develop its own GUI, the Windows OS. If you’re bilingual, trilingual, or even just use an alternative QWERY keyboard input method, such as DVORAK, you can make typing easier in Mac OS X by setting a keyboard shortcut that changes the typed language immediately.

macOS Big Sur elevates the most advanced desktop operating system in the world to a new level of power and beauty. Experience Mac to the fullest with a refined new design. Enjoy the biggest Safari update ever. Discover new features for Maps and Messages. Get even more transparency around your privacy.

Chances are, your Mac can run macOS Big Sur

The following models are supported:

• In 1996 Apple rebranded it as Mac OS, due in part to its Macintosh clone program which ended a year later. The Mac OS is characterized by its monolithic system. It was noted as easy to use and featured cooperative multitasking for the most of its history. It is the primary operating system for Apple’s Mac family of computers.
• Apple changed its naming policy with the launch of Mac OS X, known colloquially as OS X, in March 2001. After that release, Apple kept the major version number at 10 for nearly two decades.

• MacBook (2015 or later)
• MacBook Air (2013 or later)
• MacBook Pro (Late 2013 or later)
• Mac mini (2014 or later)
• iMac (2014 or later)
• iMac Pro (2017 or later)
• Mac Pro (2013 or later)

To see which model you have, click the Apple icon in your menu bar and choose About This Mac.

Make sure you’re ready to upgrade.

Before you upgrade, we recommend that you back up your Mac. If your Mac is running OS X Mavericks 10.9 or later, you can upgrade directly to macOS Big Sur. You’ll need the following:

• OS X 10.9 or later
• 4GB of memory
• 35.5GB available storage on macOS Sierra or later*
• Some features require an Apple ID; terms apply.
• Some features require a compatible internet service provider; fees may apply.

Upgrading is free and easy

Upgrading from macOS Catalina 10.15 or Mojave 10.14?

Go to Software Update in System Preferences to find macOS Big Sur. Click Upgrade Now and follow the onscreen instructions.

Upgrading from an older version of macOS?

If you’re running any release from macOS 10.13 to 10.9, you can upgrade to macOS Big Sur from the App Store. If you’re running Mountain Lion 10.8, you will need to upgrade to El Capitan 10.11 first.

If you don’t have broadband access, you can upgrade your Mac at any Apple Store.

• OS X 10.9 or later
• 4GB of memory
• 35.5GB available storage on macOS Sierra or later*

• Some features require an Apple ID; terms apply.
• Some features require a compatible internet service provider; fees may apply.

For details about your Mac model, click the Apple icon at the top left of your screen and choose About This Mac. These Mac models are compatible with macOS Big Sur:

• MacBook (2015 or later)
• MacBook Air (2013 or later)
• MacBook Pro (Late 2013 or later)
• Mac mini (2014 or later)

• iMac (2014 or later)
• iMac Pro (2017 or later)
• Mac Pro (2013 or later)

Siri

Requires a broadband internet connection and microphone (built-in or external).

Hey Siri

Supported by the following Mac models:

• MacBook Pro (2018 or later)
• MacBook Air (2018 or later)
• iMac Pro (2017 or later)

Dictation, Voice Control, and Voice Memos

Requires a microphone (built-in or external).

Spotlight Suggestions

Requires a broadband internet connection.

Gestures

Requires a Multi-Touch trackpad, Force Touch trackpad, Magic Trackpad, or Magic Mouse.

Force Touch gestures require a Force Touch trackpad.

VoiceOver gestures require a Multi-Touch trackpad, Force Touch trackpad, or Magic Trackpad.

Photo Booth

Requires a FaceTime or iSight camera (built-in or external) or USB video class (UVC) camera.

FaceTime

Audio calls require a microphone (built-in or external) and broadband internet connection.

Video calls require a built-in FaceTime camera, an iSight camera (built-in or external), or a USB video class (UVC) camera; and broadband internet connection.

Apple TV

High dynamic range (HDR) video playback is supported by the following Mac models:

• MacBook Pro (2018 or later)
• iMac Pro (2017 or later)
• Mac Pro (2019) with Pro Display XDR

Dolby Atmos soundtrack playback is supported by the following Mac models:

• MacBook Air (2018 or later)
• MacBook Pro (2018 or later)

Sidecar

Supported by the following Mac models:

• MacBook (2016 or later)
• MacBook Air (2018 or later)
• MacBook Pro (2016 or later)
• Mac mini (2018 or later)
• iMac (late 2015 or later)
• iMac Pro (2017 or later)
• Mac Pro (2019)

Supported by all iPad models with Apple Pencil support:

• 12.9-inch iPad Pro
• 11-inch iPad Pro
• 10.5-inch iPad Pro
• 9.7-inch iPad Pro
• iPad (6th generation or later)
• iPad mini (5th generation)
• iPad Air (3rd and 4th generation)

Continuity Camera

Requires an iPhone or iPad that supports iOS 12 or later.

Continuity Sketch and Continuity Markup

Requires an iPhone with iOS 13 or later or an iPad with iPadOS 13 or later.

Handoff

Requires an iPhone or iPad with a Lightning connector or with USB-C and iOS 8 or later.

Instant Hotspot

Requires an iPhone or iPad with cellular connectivity, a Lightning connector or USB-C, and iOS 8.1 or later. Requires Personal Hotspot service through your carrier.

Universal Clipboard

Requires an iPhone or iPad with a Lightning connector or with USB-C and iOS 10 or later.

Auto Unlock

Requires an Apple Watch with watchOS 3 or later or an iPhone 5 or later.

Approve with Apple Watch

Requires an Apple Watch with watchOS 6 or later or an iPhone 6s or later with iOS 13 or later.

Apple Pay on the Web

Requires a MacBook Pro or MacBook Air with Touch ID, an iPhone 6 or later with iOS 10 or later, or an Apple Watch with watchOS 3 or later.

Phone Calling

Requires an iPhone with iOS 8 or later and an activated carrier plan.

SMS

Requires an iPhone with iOS 8.1 or later and an activated carrier plan.

Home

Requires an iPhone with iOS 12 or later and a configured Home app.

AirDrop

AirDrop to iOS and iPadOS devices requires an iPhone or iPad with a Lightning connector or with USB-C and iOS 7 or later.

AirPlay

AirPlay Mirroring requires an Apple TV (2nd generation or later).

AirPlay for web video requires an Apple TV (2nd generation or later).

Peer-to-peer AirPlay requires a Mac (2012 or later) and an Apple TV (3rd generation rev A, model A1469 or later) with Apple TV software 7.0 or later.

Time Machine

Requires an external storage device (sold separately).

Maps electric vehicle routing

Requires an iPhone with iOS 14 and a compatible electric vehicle.

Maps license plate restrictions

Requires an iPhone running iOS 14 or an iPad running iPadOS 14.

Boot Camp

Allows Boot Camp installations of Windows 10 on supported Mac models.

Exchange Support

The Reverie Of Being Mac Os X

Requires Microsoft Office 365, Exchange 2016, Exchange 2013, or Exchange Server 2010. Installing the latest Service Packs is recommended.

Windows Migration

Supports OS X 10.7 or later and Windows 7 or later.

App Store

Available only to persons age 13 or older in the U.S. and many other countries and regions.

Photos

The improved Retouch tool is supported on the following Mac models:

• MacBook Pro (15-inch and 16-inch models) introduced in 2016 or later
• iMac (Retina 5K models) introduced in 2014 or later
• iMac (Retina 4K models) introduced in 2017 or later
• iMac Pro (2017 or later)
• Mac Pro introduced in 2013 or later

• Apple Books
• Apple News
• App Store
• Automator
• Calculator
• Calendar
• Chess
• Contacts
• Dictionary
• DVD Player
• FaceTime
• Find My
• Font Book
• Home
• Image Capture
• Launchpad
• Mail
• Maps

• Messages
• Mission Control
• Music
• Notes
• Photo Booth
• Photos
• Podcasts
• Preview
• QuickTime Player
• Reminders
• Safari
• Siri
• Stickies
• Stocks
• System Preferences
• TextEdit
• Time Machine
• TV
• Voice Memos

• Activity Monitor
• AirPort Utility
• Audio MIDI Setup
• Bluetooth File Exchange
• Boot Camp Assistant
• ColorSync Utility
• Console
• Digital Color Meter
• Disk Utility

• Grapher
• Keychain Access
• Migration Assistant
• Screenshot
• Screen Time
• Script Editor
• Sidecar
• System Information
• Terminal
• VoiceOver Utility

• Arabic
• Catalan
• Croatian
• Simplified Chinese
• Traditional Chinese
• Traditional Chinese (Hong Kong)
• Czech
• Danish
• Dutch
• English (Australia)
• English (UK)
• English (U.S.)
• Finnish
• French
• French (Canada)
• German
• Greek
• Hebrew
• Hindi
• Hungarian

• Indonesian
• Italian
• Japanese
• Korean
• Malay
• Norwegian
• Polish
• Brazilian Portuguese
• Portuguese
• Romanian
• Russian
• Slovak
• Spanish
• Spanish (Latin America)
• Swedish
• Thai
• Turkish
• Ukrainian
• Vietnamese

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 Mac OS X.

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.^[1] Since at that time the machine could only run one application program at a time, and there was no fixedsecondary 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[edit]

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 memory which cannot be used because they are too small, even though the total free memory may be sufficient to satisfy a particular request for memory. To solve this, Apple engineers used the concept of a relocatable handle, a reference to memory which allowed the actual data referred to be moved without invalidating the handle. Apple's scheme was simple – a handle was simply a pointer into a (non-relocatable) table of further pointers, which in turn pointed to the data.^[2] If a memory request required compaction of memory, this was done and the table, called the master pointer block, was updated. The machine itself implemented two areas in memory available for this scheme – the system heap (used for the OS), and the application heap.^[3] As long as only one application at a time was run, the system worked well. Since the entire application heap was dissolved when the application quit, fragmentation was minimized.

The memory management system had weaknesses; the system heap was not protected from errant applications, as would have been possible if the system architecture had supported memory protection, and this was frequently the cause of system problems and crashes.^[4] In addition, the handle-based approach also opened up a source of programming errors, where pointers to data within such relocatable blocks could not be guaranteed to remain valid across calls that might cause memory to move. This was a real problem for almost every system API that existed. Because of the transparency of system-owned data structures at the time, the APIs could do little to solve this. Thus the onus was on the programmer not to create such pointers, or at least manage them very carefully by dereferencing all handles after every such API call. Since many programmers were not generally familiar with this approach, early Mac programs suffered frequently from faults arising from this.^[5]

Palm OS and 16-bit Windows use a similar scheme for memory management, but the Palm and Windows versions make programmer error more difficult. For instance, in Mac OS, to convert a handle to a pointer, a program just de-references the handle directly, but if the handle is not locked, the pointer can become invalid quickly. Calls to lock and unlock handles are not balanced; ten calls to HLock are undone by a single call to HUnlock.^[6] In Palm OS and Windows, handles are an opaque type and must be de-referenced with MemHandleLock on Palm OS or Global/LocalLock on Windows. When a Palm or Windows application is finished with a handle, it calls MemHandleUnlock or Global/LocalUnlock. Palm OS and Windows keep a lock count for blocks; after three calls to MemHandleLock, a block will only become unlocked after three calls to MemHandleUnlock.

Addressing the problem of nested locks and unlocks can be straightforward (although tedious) by employing various methods, but these intrude upon the readability of the associated code block and require awareness and discipline on the part of the coder.

Memory leaks and stale references[edit]

Awareness and discipline are also necessary to avoid memory 'leaks' (failure to deallocate within the scope of the allocation) and to avoid references to stale handles after release (which usually resulted in a hard crash—annoying on a single-tasking system, potentially disastrous if other programs are running).

Switcher[edit]

The situation worsened with the advent of Switcher, which was a way for a Mac with 512KB or more of memory to run multiple applications at once.^[7] This was a necessary step forward for users, who found the one-app-at-a-time approach very limiting. Because Apple was now committed to its memory management model, as well as compatibility with existing applications, it was forced to adopt a scheme where each application was allocated its own heap from the available RAM.^[8]The amount of actual RAM allocated to each heap was set by a value coded into the metadata of each application, set by the programmer. Sometimes this value wasn't enough for particular kinds of work, so the value setting had to be exposed to the user to allow them to tweak the heap size to suit their own requirements. While popular among 'power users', this exposure of a technical implementation detail was against the grain of the Mac user philosophy. Apart from exposing users to esoteric technicalities, it was inefficient, since an application would be made to grab all of its allotted RAM, even if it left most of it subsequently unused. Another application might be memory starved, but would be unable to utilize the free memory 'owned' by another application.^[3]

While an application could not beneficially utilize a sister application's heap, it could certainly destroy it, typically by inadvertently writing to a nonsense address. An application accidentally treating a fragment of text or image, or an unassigned location as a pointer could easily overwrite the code or data of other applications or even the OS, leaving 'lurkers' even after the program was exited. Such problems could be extremely difficult to analyze and correct.

Switcher evolved into MultiFinder in System 4.2, which became the Process Manager in System 7, and by then the scheme was long entrenched. Apple made some attempts to work around the obvious limitations – temporary memory was one, where an application could 'borrow' free RAM that lay outside of its heap for short periods, but this was unpopular with programmers so it largely failed to solve the problems. Apple's System 7 Tune-up addon added a 'minimum' memory size and a 'preferred' size—if the preferred amount of memory was not available, the program could launch in the minimum space, possibly with reduced functionality. This was incorporated into the standard OS starting with System 7.1, but still did not address the root problem.^[9]

Virtual memory schemes, which made more memory available by paging unused portions of memory to disk, were made available by third-party utilities like Connectix Virtual, and then by Apple in System 7. This increased Macintosh memory capacity at a performance cost, but did not add protected memory or prevent the memory manager's heap compaction that would invalidate some pointers.

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32-bit clean[edit]

Originally the Macintosh had 128 kB of RAM, with a limit of 512 kB. This was increased to 4 MB upon the introduction of the Macintosh Plus. These Macintosh computers used the 68000 CPU, a 32-bit processor, but only had 24 physical address lines. The 24 lines allowed the processor to address up to 16 MB of memory (2²⁴ bytes), which was seen as a sufficient amount at the time. The RAM limit in the Macintosh design was 4 MB of RAM and 4 MB of ROM, because of the structure of the memory map.^[10] This was fixed by changing the memory map with the Macintosh II and the Macintosh Portable, allowing up to 8 MB of RAM.

Because memory was a scarce resource, the authors of the Mac OS decided to take advantage of the unused byte in each address. The original Memory Manager (up until the advent of System 7) placed flags in the high 8 bits of each 32-bit pointer and handle. Each address contained flags such as 'locked', 'purgeable', or 'resource', which were stored in the master pointer table. When used as an actual address, these flags were masked off and ignored by the CPU.^[4]

While a good use of very limited RAM space, this design caused problems when Apple introduced the Macintosh II, which used the 32-bit Motorola 68020 CPU. The 68020 had 32 physical address lines which could address up to 4 GB (2³² bytes) of memory. The flags that the Memory Manager stored in the high byte of each pointer and handle were significant now, and could lead to addressing errors.

In theory, the architects of the Macintosh system software were free to change the 'flags in the high byte' scheme to avoid this problem, and they did. For example, on the Macintosh IIci and later machines, HLock() and other APIs were rewritten to implement handle locking in a way other than flagging the high bits of handles. But many Macintosh application programmers and a great deal of the Macintosh system software code itself accessed the flags directly rather than using the APIs, such as HLock(), which had been provided to manipulate them. By doing this they rendered their applications incompatible with true 32-bit addressing, and this became known as not being '32-bit clean'.

In order to stop continual system crashes caused by this issue, System 6 and earlier running on a 68020 or a 68030 would force the machine into 24-bit mode, and would only recognize and address the first 8 megabytes of RAM, an obvious flaw in machines whose hardware was wired to accept up to 128 MB RAM – and whose product literature advertised this capability. With System 7, the Mac system software was finally made 32-bit clean, but there were still the problem of dirty ROMs. The problem was that the decision to use 24-bit or 32-bit addressing has to be made very early in the boot process, when the ROM routines initialized the Memory Manager to set up a basic Mac environment where NuBus ROMs and disk drivers are loaded and executed. Older ROMs did not have any 32-bit Memory Manager support and so was not possible to boot into 32-bit mode. Surprisingly, the first solution to this flaw was published by software utility company Connectix, whose 1991 product MODE32 reinitialized the Memory Manager and repeated early parts of the Mac boot process, allowing the system to boot into 32-bit mode and enabling the use of all the RAM in the machine. Apple licensed the software from Connectix later in 1991 and distributed it for free. The Macintosh IIci and later Motorola based Macintosh computers had 32-bit clean ROMs.

It was quite a while before applications were updated to remove all 24-bit dependencies, and System 7 provided a way to switch back to 24-bit mode if application incompatibilities were found.^[3] By the time of migration to the PowerPC and System 7.1.2, 32-bit cleanliness was mandatory for creating native applications and even later Motorola 68040 based Macs could not support 24-bit mode.^[6][11]

Object orientation[edit]

The rise of object-oriented languages for programming the Mac – first Object Pascal, then later C++ – also caused problems for the memory model adopted. At first, it would seem natural that objects would be implemented via handles, to gain the advantage of being relocatable. These languages, as they were originally designed, used pointers for objects, which would lead to fragmentation issues. A solution, implemented by the THINK (later Symantec) compilers, was to use Handles internally for objects, but use a pointer syntax to access them. This seemed a good idea at first, but soon deep problems emerged, since programmers could not tell whether they were dealing with a relocatable or fixed block, and so had no way to know whether to take on the task of locking objects or not. Needless to say this led to huge numbers of bugs and problems with these early object implementations. Later compilers did not attempt to do this, but used real pointers, often implementing their own memory allocation schemes to work around the Mac OS memory model.

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While the Mac OS memory model, with all its inherent problems, remained this way right through to Mac OS 9, due to severe application compatibility constraints, the increasing availability of cheap RAM meant that by and large most users could upgrade their way out of a corner. The memory was not used efficiently, but it was abundant enough that the issue never became critical. This is ironic given that the purpose of the original design was to maximise the use of very limited amounts of memory. Mac OS X finally did away with the whole scheme, implementing a modern sparse virtual memory scheme. A subset of the older memory model APIs still exists for compatibility as part of Carbon, but maps to the modern memory manager (a thread-safe malloc implementation) underneath.^[6] Apple recommends that Mac OS X code use malloc and free 'almost exclusively'.^[12]

References[edit]

The Reverie Of Being Mac Os 11

1. ^Hertzfeld, Andy (September 1983), The Original Macintosh: We're Not Hackers!, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
2. ^Hertzfeld, Andy (January 1982), The Original Macintosh: Hungarian, archived from the original on June 19, 2010, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
3. ^ ^abcmemorymanagement.org (December 15, 2000), Memory management in Mac OS, archived from the original on May 16, 2010, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
4. ^ ^abHertzfeld, Andy, The Original Macintosh: Mea Culpa, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
5. ^Apple Computer (October 1, 1985), Technical Note OV09: Debugging With PurgeMem and CompactMem, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
6. ^ ^abcLegacy Memory Manager Reference, Apple Inc., June 27, 2007, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
7. ^Hertzfeld, Andy (October 1984), The Original Macintosh: Switcher, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
8. ^Mindfire Solutions (March 6, 2002), Memory Management in Mac OS(PDF), p. 2, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
9. ^'System 7.1 upgrade guide'(PDF). Archived from the original(PDF) on March 4, 2016. Retrieved May 26, 2015.
10. ^'memory maps'. Osdata.com. March 28, 2001. Retrieved May 11, 2010.CS1 maint: discouraged parameter (link)
11. ^Apple Computer (January 1, 1991), Technical Note ME13: Memory Manager Compatibility, retrieved May 10, 2010CS1 maint: discouraged parameter (link)
12. ^Memory Allocation Recommendations on OS X, Apple Inc, July 12, 2005, retrieved September 22, 2009CS1 maint: discouraged parameter (link)

External links[edit]

• Macintosh: ROM Size for Various Models, Apple Inc, August 23, 2000, retrieved September 22, 2009CS1 maint: discouraged parameter (link)