processor upgrades Graphics Cards

iMac USB Port Speed Compared To Other Port Performance

Type A USB Port and Connector
(connects to computer)

Type B USB Port and Connector
(connects to peripheral )

USB can accommodate: * Input Devices - keyboards - mice - joysticks - graphics tablets * Storage Devices - floppy drives - hard drives - removable storage drives * Printing Devices - ink jet printers - laser printers * Imaging Devices - Scanners - Digital Cameras - Displays * Telephony Devices - modems - speakerphone modems * Connectivity Devices - hubs

Firewire Links
USB Links
What is USB?

Universal Serial Bus (USB) is a periheral bus standard that allows you to connect a variety of peripheral devices to your computer. Many Macintosh computers use Small Computer Standard Interface (SCSI), Apple Desktop Bus (ADB), and serial connections to connect peripheral devices. USB will eventually replace these standards. The iMac is the first Macintosh to incorporate this standard.

Universal Serial Bus offers:

  • plug-and-play flexibility
  • standard connectors and cables, so there will be a wide variety of solutions available to Apple customers
  • automatic configuration of devices as soon as they are connected
  • hot swapping (the connecting and disconnecting of devices while the computer is on)
  • ability to have multiple devices run simultaneously on one computer, it can support up to 127 devices!
  • Using Older Devices With New USB Standard

    Ethernet adapters will be available that will allow you to connect LocalTalk devices to iMac. And Apple also expects adapters to be available for some serial devices. However, Apple does not expect adapters to become available for SCSI devices, and Apple does not support or recommend the use of any ADB devices on iMac, even though some third parties have announced plans to make such adapters or "dongles" available.


    Theoretical Maximum Throughput

    Theoretical Maximum Throughput

    Used For

    Apple Desktop Bus

    0.01 Mbps or 10 Kbps


    input devices like mice, keyboards, joysticks, etc

    Serial Port

    0.23 Mbps or 230 Kbps


    printers, telephony devices, modems, etc

    USB at low data transfer rate

    1.5 Mbps


    most devices

    Geoport Port

    2 Mbps


    Geoport modem


    10 Mbps


    Laser printers, network connections, etc

    USB at high transfer rates

    12 Mbps


    most devices


    40 Mbps


    hardrives, removable storage, scanners, etc

    Fast SCSI

    80 Mbps


    high performance drives


    100 Mbps


    Laser printers, network connections, etc

    Ultra SCSI

    160 Mbps


    high performance drives

    Wide Ultra SCSI

    320 Mbps


    high performance drives

    Ultra2 SCSI

    320 Mbps


    high performance drives


    400 Mbps


    hard drives, scanners, digital video

    USB 2.0 (Intel)

    480 Mbps


    Standard due in late 2000 or early 2001

    Wide Ultra2 SCSI

    640 Mbps


    high performance drives


    800 Mbps


    hard drives, scanners, digital video
    Now available (3/21/00)

    Ultra3 SCSI

    1280 Mbps


    high performance drives


    1600 Mbps


    hard drives, scanners, digital video
    (Design spec up and running 3/21/00)

    What is Firewire

    FireWire is a cross-platform implementation of the high-speed serial data bus -- defined by IEEE Standard 1394-1995 -- that can move large amounts of data between computers and peripheral devices. It features simplified cabling, hot swapping, and transfer speeds of up to 400 megabits per second. Major manufacturers of multimedia devices are already adopting the FireWire technology. FireWire speeds up the movement of multimedia data and large files and enables the connection of digital consumer products -- including digital camcorders, digital video tapes, digital video disks, set-top boxes, and music systems -- directly to a personal computer.