HP 3000 Manuals HP 3000 Manuals
Defining Input/Output (I/O) Path Names
An I/O path is the physical chain that connects external hardware, such
as terminals, disk drives, and printers to the host system. The I/O path
name identifies the various components in the chain, and is the hardware
address of the connected device. In MPE V/E, I/O paths were defined
(arbitrarily relative to the hardware) in an I/O Configuration Table. In
MPE XL, I/O paths are defined by the hardware itself.
I/O paths are constructed "top down" from where a device is physically
attached to the system. In the Series 930, the chain consists of the
Mid-Bus (CTB), Channel Adapter (CA), Channel Input/Output Bus (CIO),
Device Adapter (DA), and the device itself.
The components that are identified in the path name are: the Channel
Adapter (CA) module number, the Device Adapter (DA) slot number, and a
device address.
In the Series 950, the path is similar, except the 950 provides an
additional, high speed, bus, called the System Main Bus. Bus Converters
form the interface between the System Main Bus and the Mid-Bus, Channel
Adapters, and Channel I/O Buses. This results in a difference in the I/O
path name format, as illustrated below.
Construct an I/O Path Name
The I/O path name in the Series 930 consists of:
* CA Module Number. This is the address, on the Mid-Bus, of a
Channel Adapter (CA). The CA Module Number is the number of the
card slot on the Mid-Bus Bus in which the CA is inserted,
multiplied by 4. The number is either 8, 16, or 24.
* DA Slot Number. The first CIO Bus contains 14 Device Adapter (DA)
slots, numbered 0-13. The first eight of these (#0 through #7)
are used for Device Adapters. The 13th and 14th slots (#12 and
#13) are used for the Access Port and CIO Buffer card. The 9th
through 12th slots are not supported at this time.
An additional CIO is located in an extender, and a third, containing 8
slots, can be installed. The I/O Bay can contain a total of 16 card
slots. The second and third CIO cards contain eight slots each.
* Device Address Number. This is the HP-IB address or port number
of a device.
The format of a Series 930 I/O path name is:
CA Module Number.DA Slot Number.Device Address
For example, a typical I/O path number for a disk device in a Series 930
might be:
8.0.2
The first number, 8, specifies the second Mid-Bus card slot. The second
number, 0, specifies the first DA slot in the CIO Bus. The third number,
2, is the number that was assigned to the disk device when it was
installed (HP-IB address).
A 950 Series I/O path is specified as follows:
BUS CONV/CA Module Number.DA Slot Number.Device Address
The Bus Converter (BUS CONV) specifies the number, either 2 or 6, of the
interface slot which contains the adapter boards for the SMB and the
Central Bus. The CA module specifies the number of the interface slot
that contain the adapter boards for the Central Bus and the CIO Bus. The
CA module number is assigned a numerical value of 4, 8, 16, 20, or 24.
DA CIO section slot number 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, a typical I/O path number for a disk device in Series 950
might be:
2/4.0.2
Default I/O Paths and Logical Device (LDEV) Numbers
The default paths for a basic MPE XL system reside in hardware. That
means that the hardware addresses for the System Console, tape drive, and
system disk are always available, so the system can be started even if
the configuration is bad.
When an MPE XL system is powered up or reset, two hardware routines
(Processor Dependent Code (PDC), and I/O Dependent Code (IODC)) read the
hardware resident paths and initialize the I/O paths used for booting or
rebooting the system. Paths that define the addresses of devices that
contain system boot files are referred to as boot paths.
These boot paths consist of the primary boot path (for booting from disk
resident software), the alternate boot path (for booting from a boot
tape), and the console boot path, (for specifying an autoboot without
operator intervention).
The default boot paths for a Series 925 computer are:
* Console Boot Path: 4.2.0.0.0.0.0
* Primary Boot Path: 4.1.0.0.0.0.0
* Alternate Boot Path: 4.5.0.0.0.0.0
NOTE The extra zeros on the default I/O paths are reserved for future
use.
The default boot paths for a Series 930 computer are:
* Console Boot Path: 8.1.0.0.0.0.0
* Primary Boot Path: 8.0.0.0.0.0.0
* Alternate Boot Path: 16.3.0.0.0.0.0
The default boot paths for a Series 950 computer are:
* Console Boot Path: 2/4.1.0.0.0.0.0
* Primary Boot Path: 2/4.0.0.0.0.0.0
* Alternate Boot Path: 6/4.3.0.0.0.0.0
For both Series 930 and Series 950 systems, each configured boot path
device has a preassigned ldev number. The disk drive on which the System
Master Volume is mounted will be defined as ldev 1. The System Console
will be defined as ldev 20.
For more information on configuring I/O paths and LDEV numbers, refer to
System Startup, Configuration and Shutdown Reference Manual (32650-90042)