Thursday

Apple Interfaces

Apple printer can be connecter with Apple computers in different ways. 
LocalTalk port
LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer.

Printer port on the right-hand side

 LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers, running at a rate of 230.4 kbit/s.  LocalTalk is a simple Apple network, allowing any Mac to be linked via “phone cabling”. It only supports data transfer speeds of 230kbits/sec, so it is only useful for small LAN’s and where file transfer sizes are small. All Apple printers have LocalTalk interfaces in-built, which allows far greater speeds than the basic parallel interfaces. This is especially important considering the larg
e graphic files that have to be downloaded to the printer. Apple computers normally dont have a Centronics (LPT) port!
Serial Ports
The serial ports take the form of circular 8 pin connectors. There are two ports, the printer port (marked: with a printer icon) and the modem port (marked: with a telephone handset icon). Each port is independent, and a printer can be plugged into the modem port and a modem into the printer port! Older Mac’s AppleTalk (the simple networking) can only be plugged into the printer port. More modern Macs have GeoPorts, allowing modems to draw up to 100mA of current from the computer itself. 
GeoPort
The GeoPort looks the same as older Printer/Modem ports, and performs in exactly the same way. With the release of the iMac in 1998 the traditional Mac serial port disappeared — and thus, the ability to use both LocalTalk and PhoneNet — from new models of Macintosh. LocalTalk-to-Ethernet bridges were introduced to allow legacy devices (especially laser printers) to function on newer networks. For very old Macintosh comp
uters, LocalTalk remains the only option.
Originally released as "AppleTalk Personal Network", LocalTalk used shielded twisted-pair cable with 3-pin Mini-DIN connectors. Cables were daisy-chained from transceiver to transceiver. Each transceiver had two 3-pin Mini-DIN ports, and a cable to connect to the Macs DE-9 serial connector. Later, when the Mac Plus introduced the 8-pin Mini-DIN s
erial connector, transceivers were updated as well.
USB Connection
In information technology, Universal Serial Bus (USB) is a serial bus standard to interface devices to a host computer. The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standards
 body incorporating leading companies from the computer and electronics industries. 
A typical USB connector
The Apple PowerMac G3 “Blue and White” of 1999 was the first Apple computer which provided USB. In principle it is possible to connect every printer with USB port, but there is the need of a special Apple printer driver for these models.
Today, all Apple computers have this kind of interface.
Connection via Ethernet
Ethernet is a family of frame-based computer networking technologies for local area networks (LANs). The name comes from the physical concept of the ether. It defines a number of wiring and signaling standards for the physical layer, through means of network access at the Media Access Control (MAC)/Data Link Layer, and a common addressing format.
Today, all Apple computers have built-in Ethernet with up to 1000 Bit/s. This option provides the possibility to connect to a network printer. There are different ways to connect them. The easiest way is to connect them with AppleTalk over Ethernet, which is called EtherTalk.

Ethernet network interface card

The prerequisite is that the print server provides the AppleTalk protocol. The advantage is that all Apple computers with network ability are able to print immediately without making extensive adjustments. The only thing to adjust is to choose a printer driver, a printer and a PPD with the “Chooser” of the Apple menu.
Ethernet originally used a shared coaxial cable (the shared medium) winding around a building or campus to every attached machine. A scheme known as carrier sense multiple access with collision detection (CSMA/CD) governed the way the computers shared the channel. This scheme was simpler than the competing token ring or token bus technologies.
Most of the print servers support printing over TCP/IP. The used protocol is LPR which is TCP-based. The configuration is more extensively and needs the Apple application “Desktop Printer Utility” which is included with the operating system software. This software allows the configuration of Desktop printers and printer drivers which are listed in the “Chooser” of the Apple menu.

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