IOM is a system architecture and its bus for communication between various VLSI IC

Ic

IC, ic, or i.c. may stand for:In computing and technology:* .ic.gov, a second-level domain name administered by the US Government for members of the intelligence community* Integrated circuit* Initial condition...

s for the lower layers (ref. OSI model

OSI model

The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...

) of ISDN. It was developed by Siemens

Siemens

Siemens may refer toSiemens, a German family name carried by generations of telecommunications industrialists, including:* Werner von Siemens , inventor, founder of Siemens AG...

 (today: Infineon), current revision is IOM-2. Its purpose is to enable modularity. Second sources are AMD, Alcatel

Alcatel

Alcatel Mobile Phones is a brand of mobile handsets. It was established in 2004 as a joint venture between Alcatel-Lucent of France and TCL Communication of China....

, Plessey

Plessey

The Plessey Company plc was a British-based international electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after the second world war by acquisition of companies and formed overseas companies...

.

IOM-2 is a 4-wire serial, full-duplex link. 2 operation modes are available: line card mode and terminal mode; which differ only in number and purpose of the channels. Signals are:

• DCL (data clock, 16 kHz * N, where N = number of channels)
• FSC (frame sync, 8 kHz)
• DU (data upstream)
• DD (data downstream)

(in German, p. 278ff give an overview and some application examples)