1. Mac Os Mojave
2. Bus Raiser Mac Os 11
3. Mac Os Versions

Apple Desktop Bus (ADB) is a proprietary^[1]bit-serialperipheral 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, allowing them to be connected together in a daisy chain without the need for hubs or other devices. Apple Device 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.

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• If your Mac is misbehaving, the best fix just might be a fresh reinstallation of Mac OS X – don’t forget to backup first. Leopard pales before Mac OS 8.5 for Macs left behind, dual processor benefits, and more, Dan Knight, Low End Mac Mailbag, 2007.10.23. Mac users may not remember that Mac OS 8.5 left behind some Macs just over two years old.
• Bus Driver 1.5.6 for Mac can be downloaded from our website for free. The actual developer of this Mac application is SCS Software. The application is included in Games. This Mac download was scanned by our antivirus and was rated as malware free.
• The classic Mac OS is not particularly well suited to this task, and the bus often gets bogged down at about 10 kbit/s. Early Teleport modems running at 2400 bit/s have no problems using Apple Desktop Bus, but later models were forced to move to the more expensive RS-422 ports as speeds moved to 14.4 kbit/s and higher.

History[edit]

AppleBus[edit]

Early during the creation of the Macintosh computer, the engineering team had selected the fairly sophisticated Zilog 8530 to supply serial communications. This was initially done to allow multiple devices to be plugged into a single port, using simple communication protocols implemented inside the 8530 to allow them to send and receive data with the host computer.^[2]

During development of this AppleBus system, computer networking became a vitally important feature of any computer system. With no card slots, the Macintosh was unable to easily add support for Ethernet or similar local area networking standards. Work on AppleBus was re-directed to networking purposes, and was released in 1985 as the AppleTalk system. This left the Mac with the original single-purpose mouse and keyboard ports, and no general-purpose system for low-speed devices to use.^[2]

Apple Desktop Bus[edit]

Apple Desktop Bus was created by Steve Wozniak, who had been looking for a project to work on in the mid-1980s.^[3] Someone suggested that he should create a new connection system for devices like mice and keyboards, one that would require only a single daisy-chained cable, and be inexpensive to implement.

The first system to use Apple Desktop Bus was the Apple IIGS of 1986. It was used on all Apple Macintosh machines starting with the Macintosh II and Macintosh SE. Apple Desktop Bus was also used on later models of NeXT computers.^[4] The vast majority of Apple Desktop Bus devices are for input, including trackballs, joysticks, graphics tablets and similar devices. Special-purpose uses included software protection dongles and even the TelePort modem.

Move to USB[edit]

The first Macintosh to move on from Apple Desktop Bus was the iMac in 1998, which uses USB in its place. The last Apple computer to have an Apple Desktop Bus port is the Power Macintosh G3 (Blue and White) in 1999. PowerPC-based PowerBooks and iBooks still used the Apple Desktop Bus protocol in the internal interface with the built-in keyboard and touchpad. Subsequent models use a USB-based trackpad.

Design[edit]

Mac Os Mojave

Physical[edit]

In keeping with Apple's general philosophy of industrial design, Apple Desktop Bus was intended to be as simple to use as possible,^{[citation needed]} while still being inexpensive to implement. A suitable connector was found in the form of the 4-pin mini-DIN connector, which is also used for S-Video. The connectors are small, widely available, and can only be inserted the 'correct way'. They do not lock into position, but even with a friction fit they are firm enough for light duties like those intended for Apple Desktop Bus.

Apple Desktop Bus protocol requires only a single pin for data, labeled Apple Desktop Bus. The data signal is self-clocking. Two of the other pins are used for +5 V power supply and ground. The +5 V pin guarantees at least 500 mA, and requires devices to use only 100 mA each. ADB also includes the PSW pin which is attached directly to the power supply of the host computer. This is included to allow a key on the keyboard to start up the machine without needing the Apple Desktop Bus software to interpret the signal. In more modern designs, an auxiliary microcontroller is always kept running, so it is economical to use a power-up command over the standard USB channel.

The decoding transceiverASIC as well as associated patents were controlled by Apple; this required vendors to work more closely with Apple. In the Macintosh SE, the Apple Desktop Bus is implemented in an Apple-branded Microchip PIC16CR54 Microcontroller.

Communication[edit]

The Apple Desktop Bus system is based around the devices having the ability to decode a single number (the address) and being able to hold several small bits of data (their registers). All traffic on the bus is driven by the host computer, which sends out commands to read or write data: devices are not allowed to use the bus unless the computer first requests it.

These requests take the form of single-byte strings. The upper four bits contain the address, the ID of one of the devices on the chain. The four bits allow for up to 16 devices on a single bus. The next two bits specify one of four commands, and the final two bits indicate one of four registers. The commands are:

• talk - tells the selected device to send the contents of a register to the computer
• listen - tells the device to set the register to the following value
• flush - clear the contents of a selected register
• reset - tell all devices on the bus to reset

For instance, if the mouse is known to be at address $D, the computer will periodically send out a 1-byte message on the bus that looks something like:

1101 11 00

This says that device $D (1101) should talk (11) and return the contents of register zero (00). To a mouse this means 'tell me the latest position changes'. Registers can contain between two and eight bytes. Register zero is generally the primary communications channel. Registers one and two are undefined, and are generally intended to allow 3rd party developers to store configuration information. Register three always contains device identification information.

Enumeration and identification[edit]

The addresses and enumeration of the devices are set to default values when reset. For instance, all keyboards are set to $2, and all mice to $3. When the machine is first powered on, the ADB device driver will send out talk commands asking each of these known default addresses, in turn, for the contents of register three. If no response comes from a particular address, the computer marks it dead and doesn't bother polling it later.

If a device does respond, it does so by saying it is moving to a new randomly selected higher address. The computer then responds by sending another command to that new address, asking the device to move to yet another new address. Once this completes, that device is marked live, and the system continues polling it in the future. Once all of the devices are enumerated in this fashion, the bus is ready to be used.

Although it was not common, it is possible for the Apple Desktop Bus bus to have more than one device of the same sort plugged in — two graphics tablets or software copy protection dongles, for instance. In this case when it asks for devices on that default address, both will respond and a collision could occur. The devices include a small bit of timing that allows them to avoid this problem. After receiving a message from the host, the devices wait a short random time before responding, and then only do so after 'snooping' the bus to make sure it was not busy.

With two dongles plugged in, for instance, when the bus is first setting up and queries that address, one of them will be the first to respond due to the random wait timer. The other will notice the bus was busy and not respond. The host will then send out another message to that original address, but since one device has moved to a new address, only the other will then respond. This process continues until no one responds to the request on the original address, meaning there are no more devices of that type to enumerate.

Data rates on the bus are theoretically as high as 125 kbit/s. However, the actual speed is at best half that, due to there being only one pin being shared between the computer and devices, and in practice, throughput is even less, as the entire system was driven by how fast the computer polls the bus. The classic Mac OS is not particularly well suited to this task, and the bus often gets bogged down at about 10 kbit/s. Early Teleport modems running at 2400 bit/s have no problems using Apple Desktop Bus, but later models were forced to move to the more expensive RS-422 ports as speeds moved to 14.4 kbit/s and higher.

Problems[edit]

While Mini-DIN connectors cannot be plugged in the 'wrong way', it is possible to have trouble finding the right way without looking inside the circular connector's shroud. Apple attempted to help by using U-shaped soft plastic grips around the connectors to key both plugs and sockets so the flat side has a specific relation to the shell keyway, but this feature was ignored by some third-party manufacturers. Additionally, there are four ways to orient the receiving socket on a device such as a keyboard; various Apple keyboards use at least three of these possible orientations.

The mini-DIN connector is only rated for 400 insertions and it is easy to bend a pin if not inserted with caution; in addition, the socket can become loose, resulting in intermittent function.

Some Apple Desktop Bus devices lack a pass-through connector, making it impossible to daisy-chain more than one such device at a time without obscure splitter units. Few mice or trackballs have them.

One peculiarity of Apple Desktop Bus is that in spite of being electrically unsafe for hot-swapping on all but a few machines, it has all of the basic capabilities needed for hot-swapping (like modern buses) implemented in its software and hardware. On practically all original Apple Desktop Bus systems, it is not safe to plug a device once the system is powered on. This can cause the opening of a soldered-in omfuse on the motherboard. If brought to an authorised dealer, this can result in a motherboard swap at a significant expense. A simple alternative is to obtain a fuse at a nominal cost and wire it in parallel across the open motherboard fuse (not necessarily requiring soldering).

Patents[edit]

• 4,875,158 Ashkin; Peter B. (Los Gatos, CA), Clark; Michael (Glendale, CA)
• 4,910,655 Ashkin; Peter B. (Los Gatos, CA), Clark; Michael (Glendale, CA)
• 4,912,627 Ashkin; Peter B. (Los Gatos, CA), Clark; Michael (Glendale, CA)
• 4,918,598 Ashkin; Peter B. (Los Gatos, CA), Clark; Michael (Glendale, CA)
• 5,128,677 Donovan; Paul M. (Santa Clara, CA), Caruso; Michael P. (Sudbury, MA)
• 5,175,750 Donovan; Paul M. (Santa Clara, CA), Caruso; Michael P. (Sudbury, MA)
• 5,828,857 Scalise; Albert M. (San Jose, CA)

See also[edit]

References[edit]

1. ^'ADB - The Untold Story: Space Aliens Ate My Mouse', 'Licensing' section; see also this page's Patent section.
2. ^ ^abOppenheimer, Alan (January 2004). 'A History of Macintosh Networking'. MacWorld Expo. Archived from the original on October 16, 2006.
3. ^'One cable to rule them all: a look at Apple's retired connectors through the years'
4. ^'NetBSD/next68k: Frequently Asked Questions '

External links[edit]

USB port types and names

USB (Universal Serial Bus) is an industry standard for connecting computers and other devices. It's available with many types of ports, and each type has a unique shape. On Mac, USB is available with these ports, depending on your Mac model:

USB-A

Type USB-A ports are commonly called USB, USB 2, or USB 3 ports, depending on the USB specification they support. They aren't reversible, so a USB-A connector plugs into the port only when oriented correctly.

USB-C

Type USB-C ports are available on Mac as standard USB-C ports, Thunderbolt 3 ports, and Thunderbolt / USB 4 ports. They all look the same, and the connector plugs into the port in either orientation.

Learn more about identifying the ports on your Mac, as well as the adapters and cables you can use to connect older devices to type USB-C ports.

USB specifications

USB specifications are important primarily when you want the most speed and power for your USB device, or your device needs more power or is using too much power. Every USB port supports a particular USB specification, which determines the port's maximum>USB specifications on MacData transferPower deliveryUSB 4Up to 10 GbpsUp to 15W at 5VUSB 3.1 Gen 2
Also known as USB 3.2 Gen 2
Up to 10 GbpsUp to 15W at 5VUSB 3.1 Gen 1
Also known as USB 3.2 Gen 1 or USB 3
Up to 5 GbpsUp to 900 mA at 5VUSB 2.0
Up to 480 MbpsUp to 500 mA at 5VUSB 1.1
Up to 12 MbpsUp to 500 mA at 5V

Bus Raiser Mac Os 11

To learn which specification is supported by a type USB-A or type USB-C port on your Mac model:

• Choose Apple menu  > About This Mac, click Support, then click Specifications.
• Check the System Information app for more details, including about USB devices connected to USB ports on your Mac. Select USB in the sidebar, then select a USB bus on the right.

Get the best performance from your USB devices

USB specifications all work with each other, but speed and power are limited by the cable or device that uses the earliest specification. For example, if you connect a USB 3 device to USB 2 port, your device is limited to USB 2 speeds, and it can't draw more power from the port than can be delivered over USB 2. In other words, to get the best performance, make sure that the USB port on your Mac and the USB cable to your device meet or exceed the USB specification of the device itself.

If your Mac doesn't recognize a USB device after you plug it into your Mac:

Mac Os Versions

• Check all connections: Unplug the device from your Mac, then plug it back in, and make sure that all cables and adapters are securely connected at both ends. Test with another cable or adapter, if available.
• Plug the device directly into your Mac instead of a USB hub or other device, and if necessary test with a different USB port on your Mac or device.
• Some devices need their own software, such as drivers or firmware. Others work without additional software. Check with the maker of your device, and install all available Apple software updates as well.
• If your device came with an AC power adapter, use it. Some devices can be powered by the USB port on your Mac. Others need more power than your Mac can provide.
• Restart your Mac.

Learn more

• USB 3 devices can create wireless interference that affects Wi-Fi and Bluetooth devices. Learn how to resolve Wi-Fi and Bluetooth issues caused by wireless interference.
• Mac notebook computers with USB-C, Thunderbolt 3, or Thunderbolt / USB 4 can charge over that port using a compatible USB-C power adapter and cable.