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35-522: LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer . LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers , running at a rate of 230.4 kbit/s. CSMA/CA was implemented as a random multiple access method. Networking was envisioned in the Macintosh during planning, so

70-410: A carrier wave or infrared light . The flow of data is managed with bit synchronization in synchronous serial communication or start-stop signalling and flow control in asynchronous serial communication . Sharing of the transmission medium among multiple network participants can be handled by simple circuit switching or multiplexing . More complex medium access control protocols for sharing

105-706: A design block . In mobile computing , the MIPI Alliance *-PHY family of interconnect protocols are widely used. Historically, the OSI model is closely associated with internetworking, such as the Internet protocol suite and Ethernet , which were developed in the same era, along similar lines, though with somewhat different abstractions. Beyond internetworking, the OSI abstraction can be brought to bear on all forms of device interconnection in data communications and computational electronics. The physical layer defines

140-528: A "pigtail" cable to connect to the Mac's DE-9 serial connector. Later, when the Mac Plus introduced the eight-pin mini-DIN serial connector, transceivers were updated as well. A variation of LocalTalk called PhoneNET was introduced by Farallon Computing . It used standard unshielded side-by-side telephone wire, with six-position modular connectors (same as the popular RJ11 telephone connectors) connected to

175-433: A PhoneNET transceiver, instead of the expensive, shielded, twisted-pair cable. In addition to being lower cost, PhoneNET-wired networks were more reliable due to the connections being more difficult to accidentally disconnect. In addition, because it used the "outer" pair of the modular connector, it could travel on many pre-existing phone cables and jacks where just the inner pair was in use for RJ11 telephone service. PhoneNET

210-629: A network using Open Systems Interconnection (OSI) architecture, the physical signaling sublayer is the portion of the physical layer that The Internet protocol suite , as defined in RFC 1122 and RFC 1123 , is a high-level networking description used for the Internet and similar networks. It does not define a layer that deals exclusively with hardware-level specifications and interfaces, as this model does not concern itself directly with physical interfaces. The major functions and services performed by

245-465: A network, and can be implemented through a great number of different hardware technologies with widely varying characteristics. Within the semantics of the OSI model, the physical layer translates logical communications requests from the data link layer into hardware-specific operations to cause transmission or reception of electronic (or other) signals. The physical layer supports higher layers responsible for generation of logical data packets . In

280-464: A sliding clip to mechanically secure the connection. AAUI replaces these with a small 14-position, 0.05-inch-spaced ribbon contact connector. This connector may have been chosen to avoid confusion with the monitor port on early Macintoshes , which also uses a DA-15. The connector locks into position using two clips or hooks on the sides of the connector outside of the shell which automatically clicks on when plugged in, and can be removed by pulling back on

315-567: A sliding sheath over the body of the connector, disengaging the hooks. Third-party AAUI devices often omit this sheath, requiring the user to directly squeeze small tabs on the sides of the plug housing to detach the hooks. AAUI signals have the same description, function, and electrical requirements as the Attachment Unit Interface (AUI) signals of the same name, as detailed in IEEE 802.3 -1990 CSMA/CD Standard, section 7, with

350-606: A specific physical layer protocol, for example M-PHY . Modular transceivers for fiber-optic communication (like the SFP family) complement a PHY chip and form the PMD sublayer. The Ethernet PHY is a component that operates at the physical layer of the OSI network model . It implements the physical layer portion of the Ethernet. Its purpose is to provide analog signal physical access to

385-460: Is a mechanical re-design by Apple of the standard Attachment Unit Interface (AUI) used to connect computer equipment to Ethernet . The AUI was popular in the era before the dominance of 10BASE-T networking that started in the early 1990s; the AAUI was an attempt to make the connector much smaller and more user friendly, though the proprietary nature of the interface was also criticized. AAUI

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420-631: Is able to utilize a single pair of copper wires while still communicating at the intended speeds. Texas Instruments DP83TD510E is an example of a PHY which uses SPE. Examples include the Microsemi SimpliPHY and SynchroPHY VSC82xx/84xx/85xx/86xx family, Marvell Alaska 88E1310/88E1310S/88E1318/88E1318S Gigabit Ethernet transceivers, Texas Instruments DP838xx family and offerings from Intel and ICS. The following technologies provide physical layer services: Apple Attachment Unit Interface Apple Attachment Unit Interface ( AAUI )

455-423: Is part of a system of Ethernet peripherals intended to make connecting over Ethernet easier. At the time of the introduction of AAUI, Ethernet systems usually were 10BASE2 , also known as thinnet. Apple's system is called FriendlyNet. A FriendlyNet 10BASE2 system does not use BNC T-connectors or separate 50  Ω terminators . Instead of a single BNC connector that is inserted into a T-connector placed inline,

490-450: Is responsible for electromagnetic compatibility including electromagnetic spectrum frequency allocation and specification of signal strength , analog bandwidth , etc. The transmission medium may be electrical or optical over optical fiber or a wireless communication link such as free-space optical communication or radio . Line coding is used to convert data into a pattern of electrical fluctuations which may be modulated onto

525-410: Is the link layer 's job. Similarly, Wake-on-LAN and Boot ROM functionality is implemented in the network interface card (NIC), which may have PHY, MAC, and other functionality integrated into one chip or as separate chips. Common Ethernet interfaces include fiber or two to four copper pairs for data communication. However, there now exists a new interface, called Single Pair Ethernet (SPE), which

560-420: The OSI model in a network interface controller . A PHY connects a link layer device (often called MAC as an acronym for medium access control ) to a physical medium such as an optical fiber or copper cable . A PHY device typically includes both physical coding sublayer (PCS) and physical medium dependent (PMD) layer functionality. -PHY may also be used as a suffix to form a short name referencing

595-492: The FriendlyNet transceiver has two BNC connectors, one on each side, to which the cables are attached. The transceiver automatically terminates the network if a cable is missing from either side. Additionally, Apple 10BASE2 cables terminate the network when no device is attached to them. Thus the number of mistakes that could be made hooking up a thinnet network is reduced considerably. Since any of these mistakes can disable

630-526: The Mac was given expensive RS-422 capable serial ports , first on a nine-pin D-connector , then on a mini-DIN-8 connector. The ports were driven by the Zilog SCC , which could serve as either a standard UART or handle the much more complicated HDLC protocol, which was a packet oriented protocol that incorporated addressing, bit-stuffing, and packet checksumming in hardware. Coupled together with

665-471: The RS422 electrical connections, this provided a reasonably-high-speed data connection. The 230.4 kbit/s bit rate is the highest in the series of standard serial bit rates (110, 150, 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200, 230400) derived from the 3.6864 MHz clock after the customary divide-by-16. This clock frequency, 3.6864 MHz, was chosen (in part) to support

700-743: The common asynchronous baud rates up to 38.4 kbit/s using the SCC's internal baud-rate generator. When the SCC's internal PLL was used to lock to the clock embedded in the LocalTalk serial data stream (using its FM0 encoding method) a divide-by-16 setting on the PLL yielded the fastest rate available, namely 230.4 kbit/s. Originally released as "AppleTalk Personal Network", LocalTalk used shielded twisted-pair cable with three-pin mini-DIN connectors. Cables were daisy-chained from transceiver to transceiver. Each transceiver had two three-pin mini-DIN ports, and

735-509: The cost of an external transceiver. Apple eventually abandoned the system and sold off the name. Macintosh Quadra , Centris , PowerBook 500 , Duo Dock II (for PowerBook Duo) and early Power Macintoshes have AAUI ports, which require external transceivers. By the time AAUI was nearing the end of its life, the cost of an AAUI transceiver became a burden for consumers. Later models include both AAUI and modular connector ports for directly connecting 10BASE-T; either can be used, but not both at

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770-435: The earliest Macintosh models to access a high-speed Ethernet network. With the release of the iMac in 1998 the traditional Mac serial port—and thus, the ability to use both LocalTalk and PhoneNET—disappeared from new models of Macintosh. LocalTalk-to-Ethernet bridges were introduced to allow legacy devices (especially printers ) to function on newer networks. For very old Macintosh computers, LocalTalk remains

805-419: The ends were not detachable, making it difficult to wire them through walls. Unfortunately, when mixing and matching Apple and non-Apple 10BASE2 devices, there were many seemingly natural configurations of cables and connectors which would cause the network to become unreliable or unusable in the area, reducing the value of the complex and proprietary Apple 10BASE2 wiring system. AUI uses a DA-15 connector and

840-554: The link. It is usually interfaced with a media-independent interface (MII) to a MAC chip in a microcontroller or another system that takes care of the higher layer functions. More specifically, the Ethernet PHY is a chip that implements the hardware send and receive function of Ethernet frames ; it interfaces between the analog domain of Ethernet's line modulation and the digital domain of link-layer packet signaling . The PHY usually does not handle MAC addressing, as that

875-417: The means of transmitting a stream of raw bits over a physical data link connecting network nodes . The bitstream may be grouped into code words or symbols and converted to a physical signal that is transmitted over a transmission medium . The physical layer consists of the electronic circuit transmission technologies of a network. It is a fundamental layer underlying the higher level functions in

910-431: The network segment, this presents a significant improvement. FriendlyNet equipment was expensive. Because of this, Apple's computers, billed as having built-in Ethernet, were expensive to connect to Ethernet, perhaps adding as much as a tenth to the total price of the computer system. Additionally, AAUI held no advantage for any system other than 10BASE2, and thus as 10BASE-T became ubiquitous it became impossible to justify

945-421: The newly announced Macintosh Office . However, well past the move to Ethernet, the connector's design continued to be used on all of Apple's peripherals and cable connectors as well as influencing the connectors used throughout the industry as a whole. Physical layer At the electrical layer, the physical layer is commonly implemented by dedicated PHY chip or, in electronic design automation (EDA), by

980-517: The only option. The LocalTalk connector had the distinction of being the first to use Apple's unified AppleTalk Connector Family design, created by Brad Bissell of Frog Design using Rick Meadows ' Apple Icon Family designs. LocalTalk connectors were first released in January 1985 to connect the LaserWriter printer initially with the Macintosh family of computers as an integral part of

1015-419: The physical layer are: The physical layer performs bit-by-bit or symbol-by-symbol data delivery over a physical transmission medium . It provides a standardized interface to the transmission medium, including a mechanical specification of electrical connectors and cables , for example maximum cable length, an electrical specification of transmission line signal level and impedance . The physical layer

1050-492: The physical layer include: bit rate ; point-to-point , multipoint or point-to-multipoint line configuration; physical network topology , for example bus , ring , mesh or star network ; serial or parallel communication; simplex , half duplex or full duplex transmission mode; and autonegotiation A PHY , an abbreviation for physical layer , is an electronic circuit , usually implemented as an integrated circuit , required to implement physical layer functions of

1085-759: The same time. AAUI connectors are also present on some Processor Direct Slot Ethernet adapter cards used in Macintosh LC and Performa machines. AAUI had disappeared by the late 1990s, when new Apple machines, starting with the beige Power Macintosh G3 series, include only the modular connector ports. Many third parties also created AAUI transceivers. Most made simplifications to the connectors and cables, presumably to reduce costs. Most third parties, as well as any non-Apple equipment, would use standard 10BASE2 cabling, including T-connectors and manual termination. Additionally, Apple's 10BASE2 cables were not appropriate for all uses since they only came in fixed lengths and

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1120-468: The transmission medium may use carrier sense and collision detection such as in Ethernet's Carrier-sense multiple access with collision detection (CSMA/CD). To optimize reliability and efficiency, signal processing techniques such as equalization , training sequences and pulse shaping may be used. Error correction codes and techniques including forward error correction may be applied to further improve reliability. Other topics associated with

1155-424: Was also able to use an office's existing phone wire, allowing for entire floors of computers to be easily networked. Farallon introduced a 12-port hub, which made constructing star topology networks of up to 48 devices as easy as adding jacks at the workstations and some jumpers in the phone closet. These factors led to PhoneNET largely supplanting LocalTalk wiring in low-cost networking. The useful life of PhoneNET

1190-520: Was extended with the introduction of LocalTalk switching technology by Tribe Computer Works . Introduced in 1990, the Tribe LocalSwitch was a 16-port packet switch designed to speed up overloaded PhoneNET networks. The widespread availability of Ethernet -based networking in the early 1990s led to the swift disappearance of both LocalTalk and PhoneNET. They remained in use for some time in low-cost applications and applications where Ethernet

1225-540: Was not used. Macintosh Quadra and early models of Power Macintosh supported both 10BASE2 and 10BASE-T via the Apple Attachment Unit Interface (AAUI), and all other Ethernet media via an AAUI–AUI adapter, while still supporting LocalTalk-based networking. For older Macintosh computers that did not have built-in Ethernet, a high-speed SCSI -to-Ethernet adapter was available, and was particularly popular on PowerBooks . This enabled all but

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