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System Startup, Configuration, and Shutdown Reference Manual: HP 3000 MPE/iX Computer Systems > Chapter 5 Modifying Input/Output (I/O) Configurations
I/O Paths |
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An I/O path is the system address assigned to the device interface hardware and the physical path used to reach an I/O device. When a system is powered on or reset, the processor-dependent code (PDC) and I/O-dependent code (IODC) hardware routines read and initialize the I/O paths used to boot or reboot the system. The I/O paths that are used to load the system from disk or tape are referred to as boot paths. They consist of:
Each device configured for the boot path has been assigned a unique LDEV number which identifies a physical device associated with a system. Two of the boot paths, the primary boot path and the console boot path, require a specific LDEV. The system master volume must be mounted on LDEV 1 for the operating system to be booted from disk and LDEV 20 must be assigned to the system console. At system installation, these devices are assigned a default boot path, which the system manager may redirect either through the system initialization prompts or the initial system load (ISL) interface. For more information on system initialization and ISL, refer to chapter 3 of this manual. An I/O path is determined by the channel adapter (CA) module number, the device adapter (DA) slot number, and the device address. Each I/O path is constructed "top down." On the HP 3000 Series 922 through Series 949 systems, I/O path construction begins with the channel adapter, which connects the system central bus and the channel I/O (CIO) bus. The logical construction concludes with the device adapter, which connects the CIO bus and I/O device. An I/O device connects to a device adapter card through an interface cable. An HP 3000 Series 925 through Series 949 I/O path is specified as follows:
The CA module specifies the number of the interface slots that contain the two adapter boards for the channel I/O bus (CIO) and central bus (CTB). The interface slot is assigned a numerical value of 4 or 8 for a 949 (device adapters in SPU) or 8 (device adapters in Series 925 CIO expander) or 36 or 40 for a 949 (device adapters in Series 935 CIO expander). DA CIO section slot numbers range from 0 to 13. It is recommended you use slots 0 through 7. The address of the device itself depends on the adapter. In addition, a data communications device can have an additional logical or virtual device number in the I/O path specification. For example, if the CA module number is 4, the HP-IB channel CIO interface slot is 5, and the magnetic tape device address is 0, the I/O path for the tape device is 4.5.0. On the HP 3000 Series 950 through 980 systems, I/O path construction begins with the bus converter (BUS CONV), which connects the system memory bus (SMB) and the system mid-bus. The channel adapter connects the mid-bus and the CIO bus. The logical construction concludes with the device adapter, which connects the I/O device to the CIO bus. An I/O device connects to a device adapter card through an interface cable. An HP 3000 Series 950 through Series 980 I/O path is specified as follows:
The converter specifies the number, either 2 or 6, of the interface slot which contains the adapter boards for the SMB and the mid-bus. The CA module specifies the number of the interface slots that contain the adapter boards for the mid-bus and the CIO bus. The interface slot is assigned a numerical value of 4, 8, 16, 20, or 24. DA CIO section slot numbers range from 0 to 4. The address of the device itself depends on the adapter. In addition, data communications devices may have an additional logical or virtual device number in the I/O path specification. For example, if a bus converter is 2, the CA module number is 4, the HP-IB channel CIO interface slot is 2, and the magnetic tape device address is 3, the I/O path for the tape device is 2/4.2.3. The HP 27115A Interface Card (HP-FL) is a device adapter printed circuit assembly designed for use with HP Precision Architecture computer systems that use channel input/output (CIO). The HP-FL card provides the computer system with a high-speed serial connection to peripherals over a fiber optic data link. Device-specific data is converted to a format compatible with the CIO bus. The high-speed data transfers of HP-FL cards require that HP-FL devices occupy the lowest-priority CIB slots; therefore, HP-IB systems may require reconfiguration to accommodate HP-FL cards. The reconfiguration also requires that the primary, secondary, and alternate boot paths be changed. Systems initially configured to accommodate HP-FL cards may not require significant modification to accept additional HP-FL cards. Appendix D “Default Configurations Used by INSTALL and UPDATE” lists the default I/O paths provided for use with HP-FL systems. Contact your HP representative for additional information on using HP-FL cards in your system. There are several ways to determine the I/O paths for devices that are attached to the system:
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