How the IOM Is Organized

How the IOM Is Organized

The IOM manages the I/O channels connected via the channel service (CS) busses and transfers data and control information to and from main storage via the memory interface. Each domain contains an IOM system.

IOM Logical Organization

Each IOM consists of two board types:

Input/Output Bridge (IOB) for NX5820 or KIUB for NX5820 K which provides connectivity between the system memory and the I/O bus.

Common Input/Output Module

Each CIOM comes with four channel manager facility (CMFs) which provides four CS-bus interfaces, one CS-bus per CMF.

In addition, the first CIOM of each domain allows two of it's four CS busses to be directed to the backplane to drive the internal channels. These same two CS- busses can also drive external channels.

For NX5820, one CIOM of each domain is dedicated for IOU functionality. No CMFs are available for CS-bus interfaces on this CIOM. Current NX5820 systems will only support four usable CIOMs per domain for CS-bus connectivity.

NX5820 K systems will support five usable CIOMs per domain for CS-bus connectivity. Optionally, one CIOM in domain 0 is dedicated for Multi IOU functionally, and one CIOM in domain 1 is dedicated for TCU functionally. These two CIOMs can not support CS-bus connectivity.

Figure 5–1 shows the over view of the IOM organization for the NX5820. Figure 5–2 shows the over view of the IOM organization for the NX5820 K.

Domain 0

MSM

IOM

IOB

CIOM

 

CIOM

 

**

 

CIOM

 

CIOM

 

 

CIOM

 

 

 

*

 

 

 

 

 

 

 

 

 

 

 

 

 

4 CSBs

 

 

 

4 CSBs

4 CSBs

4 CSBs

 

 

 

Domain 1

MSM

IOM

IOB

** CIOM CIOM

CIOM CIOM CIOM

*

4 CSBs 4 CSBs

4 CSBs 4 CSBs

*2 of 4 busses can drive Internal and External Channels.

** Dedicated CIOM for IOU functionality.

0710

Figure 5–1. NX5820 IOM Organization

5–2

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Unisys NX5820 manual How the IOM Is Organized, IOM Logical Organization