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Node Descriptor Record
If the preceding Perform Subsystem Function Command specified a
Set-Interface-Identifier order (x'B0') then Internal Disk returns 32 bytes of data. The
data returned has the following format:
4-142
Internal Disk Subsystem Reference Guide
Table 4-43 (Page 1 of 2). Node Descriptor Format
Byte
Description
Bytes 0-31 contain the Node Descriptor for an emulated 3990-2 of Internal Disk:
0
Node descriptor flags
Bits
Value
0-2
000
3
0
4
0
1
5
0
6
1
7
0
1
Reserved; set to zero
2
Class; set to X'01' to indicate DASD
3
Reserved; set to zero
4–9
Type Number (EBCDIC); set to the Internal Disk Subsystem type number which
is "IDSK"
10-12
Model Number (EBCDIC); set to the Internal Disk Subsystem model number
which is "002"
13-15
Manufacturer (EBCDIC); set to IBM
16-17
Manufacturing Plant Code (EBCDIC)
18-21
Host Machine Type (EBCDIC); set to '7060'
22-29
Sequence Number Low (EBCDIC); this portion of the sequence number field is
used to hold the control unit box sequence number for the Internal Disk
Subsystem. Included in this field are three leading zeros. All eight characters
are in EBCDIC notation.
30-31
Tag; the physical interface ID
Bits
Description
0
Set to B'1'
1-7
CPC ID within a complex of CPCs, set to B'0000000' by Internal Disk.
8-15
The CHPID number over which the request was received. (Internal
Disk has only one CHPID.)
Note: Bytes 32-63 contain the Node Qualifier for an emulated 3390-2 subsystem of the
Internal Disk subsystem
Note: If the Node Selector in the Set-Interface-Identifier order was b'01', only the Node
Descriptor field (bytes 0-31) is transferred.
If the Node Selector in the Set-Interface-Identifier order was b'00', the following
Node Qualifier (bytes 32-64) is added.
Meaning
Node ID is valid. Internal Disk setting.
Device Node (always 0)
External interface. Internal Disk setting.
Internal interface
Reserved - zero
This node is internal to a CPC and has no serial number
plate of it's own.
Reserved - zero
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