74-472: Lightning is a legacy proprietary computer bus and power connector, created and designed by Apple Inc. It was introduced on September 12, 2012, in conjunction with the iPhone 5 , to replace its predecessor, the 30-pin dock connector . The Lightning connector is used to connect Apple mobile devices like iPhones , iPads , and iPods to host computers, external monitors, cameras, USB battery chargers, and other peripherals. Using 8 pins instead of 30, Lightning
148-529: A FineWoven version. Apple refers to officially licensed third party MagSafe products as "Made for MagSafe". Apple worked with Belkin to design chargers using MagSafe, including a 2-in-1 charger, 3-in-1 charger and a car mount. At launch, Belkin was the only accessory maker Apple had licensed the MagSafe charging standard to; while other third-party accessory makers advertise magnetic charging products as "MagSafe compatible," they use older Qi standards that deliver
222-411: A Lightning–to–USB-C cable, and Apple recommends their newer 30 W USB-C power adapter (released in 2018), and notes their older 29 W adapter is incompatible and can only charge one device at a time. Durability testing performed by Apple Insider found that the hinge could fail with frequent folding, noting it "started to break down at 180 folds and ultimately failed at 212." The larger camera array on
296-726: A bidirectional data bus, re-using the same wires for input and output at different times. Some processors use a dedicated wire for each bit of the address bus, data bus, and the control bus. For example, the 64-pin STEbus is composed of 8 physical wires dedicated to the 8-bit data bus, 20 physical wires dedicated to the 20-bit address bus, 21 physical wires dedicated to the control bus, and 15 physical wires dedicated to various power buses. Bus multiplexing requires fewer wires, which reduces costs in many early microprocessors and DRAM chips. One common multiplexing scheme, address multiplexing , has already been mentioned. Another multiplexing scheme re-uses
370-549: A bundled MagSafe charging case. In 2023, the Wireless Power Consortium announced the Qi2 standard that is based on MagSafe. On September 9, 2024, Apple announced a 25 W MagSafe charger available in 1 m and 2 m length and that is Qi2 certified The MagSafe Charger is a single charging pad that contains recyclable rare-earth magnets surrounding a Qi wireless charging coil attached to a 1m USB-C cable. The first version of
444-726: A card plugged into the bus, which is why computers have so many slots on the bus. But through the 1980s and 1990s, new systems like SCSI and IDE were introduced to serve this need, leaving most slots in modern systems empty. Today there are likely to be about five different buses in the typical machine, supporting various devices. "Third generation" buses have been emerging into the market since about 2001, including HyperTransport and InfiniBand . They also tend to be very flexible in terms of their physical connections, allowing them to be used both as internal buses, as well as connecting different machines together. This can lead to complex problems when trying to service different requests, so much of
518-465: A maximum transfer speed of 5 Gbit/s or 625 MB/s. This requires the Lightning to USB 3 camera adapter, which allows the iPad to connect with cameras and storage peripherals, but not computers. Apple offers various adapters that allow the Lightning connector to be used with other interfaces, such as 30-pin, USB , HDMI , VGA , and SD cards . The Lightning to 30-pin adapter supports only a limited subset of
592-429: A more universal port, on its introduction, with this criticism escalating as Apple adopted USB-C as the primary connector for both data and power on the iPad Pro and MacBooks. Apple has claimed that it continues to use Lightning because replacing it would supposedly produce "an unprecedented amount of electronic waste". Some reviewers, like Business Insider senior tech correspondent Lisa Eadicicco, have posited that it
666-509: A passive backplane connected directly or through buffer amplifiers to the pins of the CPU . Memory and other devices would be added to the bus using the same address and data pins as the CPU itself used, connected in parallel. Communication was controlled by the CPU, which read and wrote data from the devices as if they are blocks of memory, using the same instructions, all timed by a central clock controlling
740-522: A second generation model that provides up to 25 W of power with the iPhone 16 / 16 Pro and is compatible with the Qi2 standard for up to 15 W of power. Apple recommends a 30 W power adapter. The MagSafe Duo Charger is a foldable charging mat with a MagSafe charger on one side and an Apple Watch charger on the other. The Apple Watch charger disc can laid flat for face-up charging or can be vertical for nightstand use. The MagSafe Duo charger can be folded when not in use. The charger came with
814-502: A second set of pins similar to those for communicating with memory—but able to operate with different speeds and protocols—to ensure that peripherals do not slow overall system performance. CPUs can also feature smart controllers to place the data directly in memory, a concept known as direct memory access . Low-performance bus systems have also been developed, such as the Universal Serial Bus (USB). Given technological changes,
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#1733085312252888-506: A serial bus inherently has no timing skew or crosstalk. USB , FireWire , and Serial ATA are examples of this. Multidrop connections do not work well for fast serial buses, so most modern serial buses use daisy-chain or hub designs. The transition from parallel to serial buses was allowed by Moore's law which allowed for the incorporation of SerDes in integrated circuits which are used in computers. Network connections such as Ethernet are not generally regarded as buses, although
962-446: A single source LRI/LRU or, as with ARINC 629, MIL-STD-1553B, and STANAG 3910, be duplex , allow all the connected LRI/LRUs to act, at different times ( half duplex ), as transmitters and receivers of data. The frequency or the speed of a bus is measured in Hz such as MHz and determines how many clock cycles there are per second; there can be one or more data transfers per clock cycle. If there
1036-433: A unified system bus . In this case, a single mechanical and electrical system can be used to connect together many of the system components, or in some cases, all of them. Later computer programs began to share memory common to several CPUs. Access to this memory bus had to be prioritized, as well. The simple way to prioritize interrupts or bus access was with a daisy chain . In this case signals will naturally flow through
1110-493: A universal ecosystem of wireless charging and accessories. Apple's chargers based on MagSafe are their first to use the Qi standard , following the development of AirPower. The MagSafe receptacle on iPhones, internally called MagSafe Attach, uses magnets to align automatically and attach to a Qi charger, ensuring reliable charging. On October 18, 2021, Apple released the 3rd generation AirPods and an updated SKU of AirPods Pro with
1184-427: A wireless charging mat capable of charging an iPhone, AirPods and Apple Watch (which uses a proprietary wireless charging system) simultaneously and the devices could be placed anywhere on the mat. However, it was canceled in early 2019 due to overheating issues due to the many overlapping coils. Apple announced MagSafe along with the iPhone 12 series on October 13, 2020, during the “Hi, Speed” Apple Special Event as
1258-457: Is a proprietary , magnetically attached wireless power transfer and accessory-attachment standard developed by Apple Inc. for its iPhone and AirPods product lines. It was announced on October 13, 2020, in conjunction with the iPhone 12 and 12 Pro series. The first version provides up to 15 W of power and is compatible with the open Qi standard for up to 7.5 W of power. The second version, announced in 2024 in conjunction with
1332-412: Is a single transfer per clock cycle it is known as Single Data Rate (SDR), and if there are two transfers per clock cycle it is known as Double Data Rate (DDR) although the use of signalling other than SDR is uncommon outside of RAM. An example of this is PCIe which uses SDR. Within each data transfer there can be multiple bits of data. This is described as the width of a bus which is the number of bits
1406-550: Is an open standard interconnect for high-speed CPU -to-device and CPU-to-memory, designed to accelerate next-generation data center performance. Many field buses are serial data buses (not to be confused with the parallel "data bus" section of a system bus or expansion card ), several of which use the RS-485 electrical characteristics and then specify their own protocol and connector: Other serial buses include: MagSafe (wireless charger)#MagSafe Duo Charger MagSafe
1480-413: Is an 8-pin digital connector. Unlike the 30-pin dock connector it replaced (and USB Type-A and -B connectors), it is reversible. Most Lightning devices only supported USB 2.0, which has a maximum transfer speed of 480 Mbit/s or 60 MB/s. With USB 2.0, only one lane is in use at a time. Only the 12.9-inch iPad Pro (1st and 2nd generation) and 10.5-inch iPad Pro support USB 3.0 (now USB 3.2 Gen 1), which has
1554-429: Is much smaller than its predecessor. The Lightning connector is reversible. The plug is indented on each side to match up with corresponding points inside the receptacle to retain the connection. In 2018, Apple began transitioning to USB-C on iPad Pros and accessories. In response to legislation to standardize charging ports passed in 2022, Apple said it would comply with regulations. The iPhone 15 and 15 Plus and
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#17330853122521628-475: Is provided by the bus—is not the case in many avionic systems , where data connections such as ARINC 429 , ARINC 629 , MIL-STD-1553B (STANAG 3838), and EFABus ( STANAG 3910 ) are commonly referred to as “data buses” or, sometimes, "databuses". Such avionic data buses are usually characterized by having several equipments or Line Replaceable Items/Units (LRI/LRUs) connected to a common, shared media . They may, as with ARINC 429, be simplex , i.e. have
1702-424: Is sent on the data bus). The width of the address bus determines the amount of memory a system can address. For example, a system with a 32-bit address bus can address 2 (4,294,967,296) memory locations. If each memory location holds one byte, the addressable memory space is 4 GB. Early processors used a wire for each bit of the address width. For example, a 16-bit address bus had 16 physical wires making up
1776-484: Is simply because Apple wants to continue profiting from its proprietary chargers and accessories. Apple introduced the MFi Program to increase the quality of the third-party accessories and consumer confidence. A phenomenon exists on Lightning connectors in which Pin 1 or Pin 4 blackens over time, causing one side of the connector to cease functioning. These pins hold either a positive or negative electrical charge . As
1850-484: Is the case, for instance, with the VESA Local Bus which lacks the two least significant bits, limiting this bus to aligned 32-bit transfers. Historically, there were also some examples of computers which were only able to address words -- word machines . The memory bus is the bus which connects the main memory to the memory controller in computer systems . Originally, general-purpose buses like VMEbus and
1924-584: The European Parliament approved regulations that require all electronic devices to support USB-C, in order to meet pressure by EU consumers regarding financial costs and electronic waste . Commentators said that these regulations will impact Apple most heavily. Apple stated concerns that this will "harm consumers in Europe and around the world", but on October 25, 2022, Greg Joswiak , Vice President of Global Marketing for Apple, said that Apple will comply with
1998-469: The IBM PC , although similar physical architecture can be employed, instructions to access peripherals ( in and out ) and memory ( mov and others) have not been made uniform at all, and still generate distinct CPU signals, that could be used to implement a separate I/O bus. These simple bus systems had a serious drawback when used for general-purpose computers. All the equipment on the bus had to talk at
2072-876: The S-100 bus were used, but to reduce latency , modern memory buses are designed to connect directly to DRAM chips, and thus are designed by chip standards bodies such as JEDEC . Examples are the various generations of SDRAM , and serial point-to-point buses like SLDRAM and RDRAM . An exception is the Fully Buffered DIMM which, despite being carefully designed to minimize the effect, has been criticized for its higher latency. Buses can be parallel buses , which carry data words in parallel on multiple wires, or serial buses , which carry data in bit-serial form. The addition of extra power and control connections, differential drivers , and data connections in each direction usually means that most serial buses have more conductors than
2146-545: The iPhone 13 Pro elevates the top end from the charger with a case, though charging is unaffected. The MagSafe Duo does not support fast charging on Apple Watches released since 2021 ( Series 7 and later, Ultra ). The MagSafe Duo was discontinued in September 2023. In July 2021, Apple released the MagSafe Battery Pack. It contains a 11.13Wh, 1,460mAh battery that on its own can charge an iPhone at up to 7.5 W. While
2220-525: The iPhone 15 Pro and Pro Max , announced on September 12, 2023, became the first iPhones to use USB-C , and the last few Lightning accessories will make the transition by 2025. The Lightning connector was introduced on September 12, 2012, with the iPhone 5 , as a replacement for the 30-pin dock connector. The iPod Touch (5th generation) , iPod Nano (7th generation), iPad (4th generation) and iPad Mini (1st generation) followed in October and November 2012 as
2294-444: The iPhone 16 and 16 Pro , provides up to 25 W of power and is compatible with the Qi2 standard for up to 15 W of power. The connector also enables connecting non-charger accessories such as card holders and cases with communication through an integrated NFC loop. The charger uses a circle of rare-earth magnets . Apple released two chargers using the MagSafe standard in 2020:
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2368-426: The 12 series at around half the speed of third party 7.5 W Qi chargers. Devices without MagSafe need to be manually aligned as they do not have the built-in array of magnets that interlock with MagSafe. Apple recommends a 20 W power adapter. Users have reported MagSafe Chargers leaving circular imprints on leather cases. On September 9, 2024, Apple discontinued the original MagSafe Charger and replaced it with
2442-535: The 2020 iPad Air (4th generation) , 2021 iPad Mini (6th generation) , and 2022 iPad (10th generation) similarly replaced Lightning with USB-C. In October 2022, Apple released the Siri Remote for the 3rd generation Apple TV 4K with a USB-C connector, becoming Apple's first accessory to charge via USB-C. In January 2020, the European Commission proposed laws to standardize charger ports. On October 4, 2022,
2516-399: The CPU and main memory tend to be tightly coupled, with the internal bus connecting the two being known as the system bus . In systems that include a cache , CPUs use high-performance system buses that operate at speeds greater than memory to communicate with memory. The internal bus (also known as the internal data bus, memory bus or system bus ) connects internal components of a computer to
2590-468: The IEEE "Superbus" study group, the open microprocessor initiative (OMI), the open microsystems initiative (OMI), the "Gang of Nine" that developed EISA , etc. Early computer buses were bundles of wire that attached computer memory and peripherals. Anecdotally termed the " digit trunk " in the early Australian CSIRAC computer, they were named after electrical power buses, or busbars . Almost always, there
2664-453: The Lightning connector in media were mixed: publications appreciated the reversibility and increased durability of the connector but were critical of its proprietary nature, of the effects of its authentication protocol on third-party accessory availability, and of the lack of performance improvements over the 30-pin dock connector. Reviewers criticised Apple for continuing to include a Lightning port on its products instead of moving to USB-C ,
2738-497: The MagSafe Charger released in 2020 delivers up to 15 W of power on the iPhone 12/12 Pro and newer, with the exception of the iPhone 12 Mini and 13 Mini, which support 12 W. The Wall Street Journal found MagSafe charged at half the speed of a 20W wired charger. MagSafe can also charge other Qi-certified devices, including older iPhone models and AirPods, though testing by MacRumors found that MagSafe charged iPhones older than
2812-477: The MagSafe Charger, which is a single charging pad for iPhone, and the MagSafe Duo Charger, which is a charging mat with both MagSafe and an Apple Watch charger. Apple has also licensed the MagSafe standard to third parties to develop chargers and cases. In 2021, Apple released the MagSafe Battery Pack and added MagSafe charging to AirPods and AirPods Pro . The MagSafe name was first used by Apple for
2886-533: The address bus pins as the data bus pins, an approach used by conventional PCI and the 8086 . The various "serial buses" can be seen as the ultimate limit of multiplexing, sending each of the address bits and each of the data bits, one at a time, through a single pin (or a single differential pair). Over time, several groups of people worked on various computer bus standards, including the IEEE Bus Architecture Standards Committee (BASC),
2960-461: The available 30-pin signals: USB data, USB charging, and analog audio output (via the DAC inside of the adapter). Lightning connectors contain an authentication chip that makes it difficult for third-party manufacturers to produce compatible accessories without being approved by Apple. The authentication scheme has been cracked by some third parties. The connector is 6.7 mm by 1.5 mm. Initial opinions of
3034-489: The bits themselves, and allows for an increase in data transfer speed without increasing the frequency of the bus. The effective or real data transfer speed/rate may be lower due to the use of encoding that also allows for error correction such as 128/130b (b for bit) encoding. The data transfer speed is also known as the bandwidth. The simplest system bus has completely separate input data lines, output data lines, and address lines. To reduce cost, most microcomputers have
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3108-493: The bus can transfer per clock cycle and can be synonymous with the number of physical electrical conductors the bus has if each conductor transfers one bit at a time. The data rate in bits per second can be obtained by multiplying the number of bits per clock cycle times the frequency times the number of transfers per clock cycle. Alternatively a bus such as PCIe can use modulation or encoding such as PAM4 which groups 2 bits into symbols which are then transferred instead of
3182-409: The bus had to talk at the same speed. While the CPU was now isolated and could increase speed, CPUs and memory continued to increase in speed much faster than the buses they talked to. The result was that the bus speeds were now much slower than what a modern system needed, and the machines were left starved for data. A particularly common example of this problem was that video cards quickly outran even
3256-511: The bus in physical or logical order, eliminating the need for complex scheduling. Digital Equipment Corporation (DEC) further reduced cost for mass-produced minicomputers , and mapped peripherals into the memory bus, so that the input and output devices appeared to be memory locations. This was implemented in the Unibus of the PDP-11 around 1969. Early microcomputer bus systems were essentially
3330-615: The bus supplied power, but often use a separate power source. This distinction is exemplified by a telephone system with a connected modem , where the RJ11 connection and associated modulated signalling scheme is not considered a bus, and is analogous to an Ethernet connection. A phone line connection scheme is not considered to be a bus with respect to signals, but the Central Office uses buses with cross-bar switches for connections between phones. However, this distinction—that power
3404-457: The bus. As the buses became wider and lengthier, this approach became expensive in terms of the number of chip pins and board traces. Beginning with the Mostek 4096 DRAM , address multiplexing implemented with multiplexers became common. In a multiplexed address scheme, the address is sent in two equal parts on alternate bus cycles. This halves the number of address bus signals required to connect to
3478-431: The cards to be much more complex. These buses also often addressed speed issues by being "bigger" in terms of the size of the data path, moving from 8-bit parallel buses in the first generation, to 16 or 32-bit in the second, as well as adding software setup (now standardised as Plug-n-play ) to supplant or replace the jumpers. However, these newer systems shared one quality with their earlier cousins, in that everyone on
3552-426: The classical terms "system", "expansion" and "peripheral" no longer have the same connotations. Other common categorization systems are based on the bus's primary role, connecting devices internally or externally. However, many common modern bus systems can be used for both. SATA and the associated eSATA are one example of a system that would formerly be described as internal, while certain automotive applications use
3626-491: The computer into two "worlds", the CPU and memory on one side, and the various devices on the other. A bus controller accepted data from the CPU side to be moved to the peripherals side, thus shifting the communications protocol burden from the CPU itself. This allowed the CPU and memory side to evolve separately from the device bus, or just "bus". Devices on the bus could talk to each other with no CPU intervention. This led to much better "real world" performance, but also required
3700-534: The conductive power connectors of its MacBook lineup, beginning with the 2006 MacBook Pro . It began to be phased out upon the release of the Touch Bar MacBook Pro in 2016, which used USB Power Delivery and the USB-C connector for charging. MagSafe was discontinued across MacBooks in 2019 but reintroduced with 14-inch and 16-inch MacBook Pro models released in October 2021. In 2017, Apple announced AirPower ,
3774-524: The contacts, instead of gold plating, which improved durability, reducing the possibility of corrosion. Bus (computing) In computer architecture , a bus (historically also called data highway or databus ) is a communication system that transfers data between components inside a computer , or between computers. This expression covers all related hardware components (wire, optical fiber , etc.) and software , including communication protocols . In most traditional computer architectures ,
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#17330853122523848-489: The difference is largely conceptual rather than practical. An attribute generally used to characterize a bus is that power is provided by the bus for the connected hardware. This emphasizes the busbar origins of bus architecture as supplying switched or distributed power. This excludes, as buses, schemes such as serial RS-232 , parallel Centronics , IEEE 1284 interfaces and Ethernet, since these devices also needed separate power supplies. Universal Serial Bus devices may use
3922-406: The first devices with Lightning. On November 25, 2012, Apple acquired the "Lightning" trademark in Europe from Harley-Davidson . Apple was given a partial transfer of the Lightning trademark, suggesting that Harley-Davidson likely retained the rights to use the name for motorcycle-related products. The first-generation iPad Pro (12.9-inch models only), and the second-generation iPad Pro , are
3996-400: The first half of the memory address or the second half. Accessing an individual byte frequently requires reading or writing the full bus width (a word ) at once. In these instances the least significant bits of the address bus may not even be implemented - it is instead the responsibility of the controlling device to isolate the individual byte required from the complete word transmitted. This
4070-532: The gold plating of the pins wears out over time when the connector is connected while it is stained with liquid-like sweats, a spark gap can be produced due to extra current being drawn to a capacitor for a short period. This spark gap causes the copper pins to corrode, blackening them. In 2019, Apple released new versions of the Lightning connector and ceased production of the older versions. These new versions included many improvements over older versions, including new silver-colored ruthenium - rhodium plating of
4144-632: The input and output of a given bus. IBM introduced these on the IBM 709 in 1958, and they became a common feature of their platforms. Other high-performance vendors like Control Data Corporation implemented similar designs. Generally, the channel controllers would do their best to run all of the bus operations internally, moving data when the CPU was known to be busy elsewhere if possible, and only using interrupts when necessary. This greatly reduced CPU load, and provided better overall system performance. To provide modularity, memory and I/O buses can be combined into
4218-448: The memory. For example, a 32-bit address bus can be implemented by using 16 lines and sending the first half of the memory address, immediately followed by the second half memory address. Typically two additional pins in the control bus – row-address strobe (RAS) and column-address strobe (CAS) – are used to tell the DRAM whether the address bus is currently sending
4292-446: The minimum of one used in 1-Wire and UNI/O . As data rates increase, the problems of timing skew , power consumption, electromagnetic interference and crosstalk across parallel buses become more and more difficult to circumvent. One partial solution to this problem has been to double pump the bus. Often, a serial bus can be operated at higher overall data rates than a parallel bus, despite having fewer electrical connections, because
4366-461: The mother board. Local buses connect the CPU and memory to the expansion bus , which in turn connects the computer to peripherals. Bus systems such as the SATA ports in modern computers support multiple peripherals, allowing multiple hard drives to be connected without an expansion card . In systems that have a similar architecture to multicomputers , but which communicate by buses instead of networks,
4440-414: The new EU regulations, indirectly confirming that iPhone models and other devices will ultimately replace Lightning with USB-C in the future. Released on September 22, 2023, the iPhone 15 / 15 Pro series are the first iPhone models to use USB-C. This means all the latest iPad models since March 18, 2022, and iPhone models since September 22, 2023, have transitioned to USB-C. The 2nd generation AirPods Pro
4514-401: The newer bus systems like PCI , and computers began to include AGP just to drive the video card. By 2004 AGP was outgrown again by high-end video cards and other peripherals and has been replaced by the new PCI Express bus. An increasing number of external devices started employing their own bus systems as well. When disk drives were first introduced, they would be added to the machine with
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#17330853122524588-463: The only devices in which the Lightning connector supports USB 3.0 host. The only accessory released with USB 3.0 support is the Lightning to USB 3 Camera Adapter. Since iPhone 8 and iPhone X , the Lightning connector is somewhat USB-PD compatible. In October 2018, following the implementation of USB-C across the Mac lineup, Apple released a range of iPad Pro models that replaced Lightning with it;
4662-677: The pack is being charged via Lightning it can charge an iPhone at up to 15 W. The pack itself can be charged either directly through its Lightning port or wirelessly from an iPhone that is being charged via Lightning. The MagSafe Battery Pack was discontinued in September 2023 after the iPhone 15 series was released, which charges via USB-C rather than Lightning. Apple released a line of MagSafe cases and other accessories, such as leather sleeves and wallets that can attach magnetically to iPhones and cases with MagSafe. Apple states MagSafe charging works through their cases. Apple states that their leather wallets are shielded to protect credit cards from
4736-502: The peripheral bus, which includes bus systems like PCI. Early computer buses were parallel electrical wires with multiple hardware connections, but the term is now used for any physical arrangement that provides the same logical function as a parallel electrical busbar . Modern computer buses can use both parallel and bit serial connections, and can be wired in either a multidrop (electrical parallel) or daisy chain topology, or connected by switched hubs. Many modern CPUs also feature
4810-441: The primarily external IEEE 1394 in a fashion more similar to a system bus. Other examples, like InfiniBand and I²C were designed from the start to be used both internally and externally. An address bus is a bus that is used to specify a physical address . When a processor or DMA -enabled device needs to read or write to a memory location, it specifies that memory location on the address bus (the value to be read or written
4884-484: The program attempted to perform those other tasks, it might take too long for the program to check again, resulting in loss of data. Engineers thus arranged for the peripherals to interrupt the CPU. The interrupts had to be prioritized, because the CPU can only execute code for one peripheral at a time, and some devices are more time-critical than others. High-end systems introduced the idea of channel controllers , which were essentially small computers dedicated to handling
4958-427: The rare-earth magnets used in these accessories, although warns that credit cards should not be placed between an iPhone and a MagSafe charger. In 2021, Apple released an updated MagSafe wallet with an NFC chip that supports Find My location tracking when the wallet is disconnected from an iPhone, but is not supported by Apple's clear cases for iPhone 12 models. In 2023, Apple replaced the leather MagSafe wallet with
5032-420: The same speed, as it shared a single clock. Increasing the speed of the CPU becomes harder, because the speed of all the devices must increase as well. When it is not practical or economical to have all devices as fast as the CPU, the CPU must either enter a wait state , or work at a slower clock frequency temporarily, to talk to other devices in the computer. While acceptable in embedded systems , this problem
5106-518: The speed of the CPU. Still, devices interrupted the CPU by signaling on separate CPU pins. For instance, a disk drive controller would signal the CPU that new data was ready to be read, at which point the CPU would move the data by reading the "memory location" that corresponded to the disk drive. Almost all early microcomputers were built in this fashion, starting with the S-100 bus in the Altair 8800 computer system. In some instances, most notably in
5180-399: The system bus is known as a front-side bus . In such systems, the expansion bus may not share any architecture with their host CPUs, instead supporting many different CPUs, as is the case with PCI . While the term " peripheral bus " is sometimes used to refer to all other buses apart from the system bus, the "expansion bus" has also been used to describe a third category of buses separate from
5254-522: The work on these systems concerns software design, as opposed to the hardware itself. In general, these third generation buses tend to look more like a network than the original concept of a bus, with a higher protocol overhead needed than early systems, while also allowing multiple devices to use the bus at once. Buses such as Wishbone have been developed by the open source hardware movement in an attempt to further remove legal and patent constraints from computer design. The Compute Express Link (CXL)
5328-441: Was not tolerated for long in general-purpose, user-expandable computers. Such bus systems are also difficult to configure when constructed from common off-the-shelf equipment. Typically each added expansion card requires many jumpers in order to set memory addresses, I/O addresses, interrupt priorities, and interrupt numbers. "Second generation" bus systems like NuBus addressed some of these problems. They typically separated
5402-402: Was one bus for memory, and one or more separate buses for peripherals. These were accessed by separate instructions, with completely different timings and protocols. One of the first complications was the use of interrupts . Early computer programs performed I/O by waiting in a loop for the peripheral to become ready. This was a waste of time for programs that had other tasks to do. Also, if
5476-842: Was updated to a USB-C charging case and the MagSafe Duo Charger and MagSafe Battery Pack , which used the Lightning connector, were discontinued. The Lightning connector (used on iPhone 5 until iPhone 14 ) has a technical constraint that limits video output using the Lightning Digital AV HDMI Adapter to a maximum supported resolution of 1600 x 900 (slightly less than 1080p ). The USB-C ports on iPhone 15 and thereafter supports DisplayPort Alternate Mode over USB-C video output with HDR up to 4K resolution . Apple has subsequently transitioned its AirPods (on 9th September 2024) and Magic Mouse, Magic Trackpad and Magic Keyboard (all on October 28th, 2024) to USB-C. Lightning
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