LocalTalk

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Apple LocalTalk box interior 1.jpg
Apple LocalTalk box interior 2 - auto termination switch.jpg
Interior of Apple LocalTalk interface box. In 1989, these boxes typically cost US$90 (equivalent to $220in 2023 [1] ) each. The connectors feature automatic electrical termination of the LocalTalk signal bus; insertion of a LocalTalk bus cable depresses a normally closed switch behind the connector, disabling termination for that connector.

LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer.

Contents

LocalTalk specifies a system of shielded twisted pair cabling, [2] plugged into self-terminating transceivers, running at a rate of 230.4 kbit/s. CSMA/CA was implemented as a random multiple access method.

Farallon's competing PhoneNet transceiver Farlon localtalk.jpg
Farallon's competing PhoneNet transceiver

Networking was envisioned in the Macintosh during planning, so 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 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 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 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 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 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 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 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.[ citation needed ] This enabled all but the earliest Macintosh models to access a high-speed Ethernet network.

With the release of the iMac in 1998 the traditional Mac serial portand thus, the ability to use both LocalTalk and PhoneNETdisappeared 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 the only option.

Design legacy

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.[ citation needed ] 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 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.[ citation needed ]

Related Research Articles

AppleTalk is a discontinued proprietary suite of networking protocols developed by Apple Computer for their Macintosh computers. AppleTalk includes a number of features that allow local area networks to be connected with no prior setup or the need for a centralized router or server of any sort. Connected AppleTalk-equipped systems automatically assign addresses, update the distributed namespace, and configure any required inter-networking routing.

<span class="mw-page-title-main">Network topology</span> Arrangement of a communication network

Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

<span class="mw-page-title-main">Apple Attachment Unit Interface</span> Apple version of the standard Ethernet connection

Apple Attachment Unit Interface (AAUI) 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.

<span class="mw-page-title-main">Serial port</span> Communication interface transmitting information sequentially

On computers, a serial port is a serial communication interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in parallel. Throughout most of the history of personal computers, data has been transferred through serial ports to devices such as modems, terminals, various peripherals, and directly between computers.

<span class="mw-page-title-main">Apple Desktop Bus</span> Proprietary bit-serial peripheral bus

Apple Desktop Bus (ADB) is a proprietary bit-serial peripheral bus connecting low-speed devices to computers. It was introduced on the Apple IIGS in 1986 as a way to support low-cost devices like keyboards and mice, enabling them to be connected together in a daisy chain without the need for hubs or other devices. Apple Desktop Bus was quickly introduced on later Macintosh models, on later models of NeXT computers, and saw some other third-party use as well. Like the similar PS/2 connector used in many PC-compatibles at the time, Apple Desktop Bus was rapidly replaced by USB as that system became popular in the late 1990s; the last external Apple Desktop Bus port on an Apple product was in 1999, though it remained as an internal-only bus on some Mac models into the 2000s.

<span class="mw-page-title-main">Serial communication</span> Type of data transfer

In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels.

GeoPort is a serial data system used on some models of the Apple Macintosh that could be externally clocked to run at a 2 megabit per second data rate. GeoPort slightly modified the existing Mac serial port pins to allow the computer's internal DSP hardware or software to send data that, when passed to a digital-to-analog converter, emulated various devices such as modems and fax machines. GeoPort could be found on late-model 68K-based machines as well as many pre-USB Power Macintosh models and PiPPiN. Some later Macintosh models also included an internal GeoPort via an internal connector on the Communications Slot. Apple GeoPort technology is now obsolete, and modem support is typically offered through USB.

<span class="mw-page-title-main">Registered jack</span> Telecommunication network interface

A registered jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a computer service provided by a local exchange carrier or long distance carrier. Registered interfaces were first defined in the Universal Service Ordering Code (USOC) system of the Bell System in the United States for complying with the registration program for customer-supplied telephone equipment mandated by the Federal Communications Commission (FCC) in the 1970s. They were subsequently codified in title 47 of the Code of Federal Regulations Part 68. Registered jack connections began to see use after their invention in 1973 by Bell Labs. The specification includes physical construction, wiring, and signal semantics. Accordingly, registered jacks are primarily named by the letters RJ, followed by two digits that express the type. Additional letter suffixes indicate minor variations. For example, RJ11, RJ14, and RJ25 are the most commonly used interfaces for telephone connections for one-, two-, and three-line service, respectively. Although these standards are legal definitions in the United States, some interfaces are used worldwide.

<span class="mw-page-title-main">Attachment Unit Interface</span> Physical and logical interface defined in the original Ethernet standard

The Attachment Unit Interface (AUI) is a physical and logical interface defined in the original IEEE 802.3 standard for 10BASE5 Ethernet and the previous DIX standard. The physical interface consists of a 15-pin D-subminiature connection that provides a path between an Ethernet node's physical signaling and the Medium Attachment Unit (MAU), sometimes also known as a transceiver. An AUI cable may be up to 50 metres long, although frequently the cable is omitted altogether and the MAU and medium access controller MAC are directly attached to one another. On Ethernet implementations without separate MAU and MAC, the AUI is omitted.

<span class="mw-page-title-main">RS-422</span> Standard for serial communication

RS-422, also known as TIA/EIA-422, is a technical standard originated by the Electronic Industries Alliance, first issued in 1975, that specifies electrical characteristics of a digital signaling circuit. It was meant to be the foundation of a suite of standards that would replace the older RS-232C standard with standards that offered much higher speed, better immunity from noise, and longer cable lengths. RS-422 systems can transmit data at rates as high as 10 Mbit/s, or may be sent on cables as long as 1,200 meters (3,900 ft) at lower rates. It is closely related to RS-423, which uses the same signaling systems but on a different wiring arrangement.

<span class="mw-page-title-main">Medium Attachment Unit</span>

A Medium Attachment Unit (MAU) is a transceiver which converts signals on an Ethernet cable to and from Attachment Unit Interface (AUI) signals.

<span class="mw-page-title-main">PhoneNET</span> Implementation of AppleTalks physical layer

PhoneNET was an implementation of the AppleTalk networking physical layer created by Farallon Computing(now Netopia).

Farallon, later renamed Netopia, was a computer networking company headquartered in Berkeley, and subsequently Emeryville, California, that produced a wide variety of products including bridges, repeaters and switches, and in their later Netopia incarnation, modems, routers, gateways, and Wi-Fi devices. The company also produced the NBBS and, as Farallon, Timbuktu remote administration software, as well as the MacRecorder, the first audio capture and manipulation products for the Macintosh. The company was founded in 1986 and changed its name to Netopia in 1998. Farallon originated several notable technologies, including:

<span class="mw-page-title-main">PowerBook 500 series</span> Range of Apple Macintosh PowerBook portable computers

The PowerBook 500 series is a range of Apple Macintosh PowerBook portable computers first introduced by Apple Computer with the 540c model on May 16, 1994. It was the first to have stereo speakers, a trackpad, and Ethernet networking built-in.

<span class="mw-page-title-main">Computer port (hardware)</span> Computer hardware

A computer port is a hardware piece on a computer where an electrical connector can be plugged to link the device to external devices, such as another computer, a peripheral device or network equipment.

<span class="mw-page-title-main">Modular connector</span> Electrical connector commonly used in telephone and computer networks

A modular connector is a type of electrical connector for cords and cables of electronic devices and appliances, such as in computer networking, telecommunication equipment, and audio headsets.

<span class="mw-page-title-main">GatorBox</span>

The GatorBox is a LocalTalk-to-Ethernet bridge, a router used on Macintosh-based networks to allow AppleTalk communications between clients on LocalTalk and Ethernet physical networks. The GatorSystem software also allowed TCP/IP and DECnet protocols to be carried to LocalTalk-equipped clients via tunneling, providing them with access to these normally Ethernet-only systems.

<span class="mw-page-title-main">Apple Communication Slot</span> Expansion data interface in Apple Macintosh computers

The Apple Communication Slot, or Comm Slot, is an internal expansion data interface (slot) found in Apple Macintosh computers from the early to mid-1990s. It was designed as an inexpensive way to add communication expansion cards like network adapters or modems to Macs and Power Macs.

TOPS is a peer-to-peer LAN-based file sharing system best known in its Macintosh implementation, but also available for DOS and able to interoperate with Unix's NFS. Originally written by Centram Systems West, the company was purchased by Sun Microsystems as part of Sun's development of the NFS ecosystem. The Centram company was renamed to TOPS after its acquisition by Sun. Sales of TOPS dried up after the introduction of System 7, which featured a similar file sharing system built-in, and Sun spun off their NFS developments to Sitka.

<span class="mw-page-title-main">MacEnhancer</span> Expansion box for the Compact Macintosh

The MacEnhancer is an expansion box originally developed in 1985 by Microsoft for Apple Computer's original Macintosh. Plugged into either the Macintosh's serial printer or modem ports, the MacEnhancer provides IBM-standard printer and serial ports as well as a passthrough for the Mac-standard serial port, for a net gain of three peripheral ports. Along with a provided disk of drivers, this expansion box allows the Macintosh to run a host of printers and other business peripherals not originally supported by Apple.

References

  1. 1634–1699: McCusker, J. J. (1997). How Much Is That in Real Money? A Historical Price Index for Use as a Deflator of Money Values in the Economy of the United States: Addenda et Corrigenda (PDF). American Antiquarian Society. 1700–1799: McCusker, J. J. (1992). How Much Is That in Real Money? A Historical Price Index for Use as a Deflator of Money Values in the Economy of the United States (PDF). American Antiquarian Society. 1800–present: Federal Reserve Bank of Minneapolis. "Consumer Price Index (estimate) 1800–" . Retrieved February 29, 2024.
  2. "AppleTalk Overview" (PDF). Cisco . February 2, 2010. Retrieved March 21, 2023.

See also