A multidrop bus (MDB) is a

computer bus In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical ...

able to connect three or more devices. A process of

arbitration Arbitration is a formal method of dispute resolution involving a third party neutral who makes a binding decision. The third party neutral (the 'arbitrator', 'arbiter' or 'arbitral tribunal') renders the decision in the form of an 'arbitrati ...

determines which device sends information at any point. The other devices listen for the data they are intended to receive. Multidrop buses have the advantage of simplicity and extensibility, but their differing electrical characteristics make them relatively unsuitable for high frequency or high bandwidth applications.

In computing

Since 2000, multidrop standards such as

PCI PCI may refer to: Business and economics * Payment card industry, businesses associated with debit, credit, and other payment cards ** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors * Prov ...

and

Parallel ATA Parallel ATA (PATA), originally , also known as Integrated Drive Electronics (IDE), is a standard interface designed for IBM PC-compatible computers. It was first developed by Western Digital and Compaq in 1986 for compatible hard drives and C ...

are increasingly being replaced by point-to-point systems such as

PCI Express PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a high-speed standard used to connect hardware components inside computers. It is designed to replace older expansion bus standards such as Peripher ...

and

SATA SATA (Serial AT Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the earlier Parallel ATA (PATA) standard ...

. Modern

SDRAM Synchronous dynamic random-access memory (synchronous dynamic RAM or SDRAM) is any DRAM where the operation of its external pin interface is coordinated by an externally supplied clock signal. DRAM integrated circuits (ICs) produced from the ...

chips exemplify the problem of electrical impedance discontinuity.

Fully Buffered DIMM A Fully Buffered DIMM (FB-DIMM) is a type of memory module used in computer systems. It is designed to improve memory performance and capacity by allowing multiple memory modules to be each connected to the memory controller using a serial interfa ...

is an alternative approach to connecting multiple

DRAM Dram, DRAM, or drams may refer to: Technology and engineering * Dram (unit), a unit of mass and volume, and an informal name for a small amount of liquor, especially whisky or whiskey * Dynamic random-access memory, a type of electronic semicondu ...

modules to a memory controller.

For vending machines

MDB/ICP

MDB/ICP (formerly known as MDB) is a multidrop bus computer networking protocol used within the vending machine industry, currently published by the American

National Automatic Merchandising Association The National Automatic Merchandising Association (NAMA) is the American national trade association of the convenience services industry, including vending, micro markets, office coffee service, and foodservice management. Headquartered in Arlingto ...

ccTalk

The ccTalk multidrop bus protocol uses an TTL-level asynchronous serial protocol. It uses address randomization to allow multiple similar devices on the bus (after randomisation the devices can be distinguished by their serial number). ccTalk was developed by CoinControls, but is used by multiple vendors.

External links

IBM Journal of Research and Development
{{DEFAULTSORT:Multidrop Bus Computer buses

In computing

For vending machines

MDB/ICP

ccTalk

See also

External links