Multidrop bus

A multidrop bus (MDB) is a computer bus able to connect three or more devices. A process of arbitration 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.

Since 2000,^{[citation needed]} multidrop standards such as PCI and Parallel ATA are increasingly being replaced by point-to-point systems such as PCI Express and SATA. Modern SDRAM chips exemplify the problem of electrical impedance discontinuity.^{[clarification needed]} Fully Buffered DIMM is an alternative approach to connecting multiple DRAM modules to a memory controller.

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 ccTalk multidrop bus protocol uses an 8 bit 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.

• Bus network topology
• EIA-485
• 1-Wire
• Open collector
• I2C

• IBM Journal of Research and Development