9. For output spooling devices, the VDEVEXTN field (displacement X'10') contains the pointer to the virtual spool extension block, VSPXBLOK. 10. The value of the VDEVFLG2 field (displacement X'38') describes the
Reserve/Release flags. Value of X'80' X'40' X'20' X'10' Comments Process-virtual Reserve/Release commands
Minidisk reserved by VDEVUSER VDEVBLOK to get device end when minidisk released Virtual I/O waiting for release on minidisk
11. For Reserve/Release minidisks, VDEVRRB (displacement X'3C') contains
the address of the VRRBLOK. The address of the first RCHBLOK is found in the ARIOCH field
(displacement X'3B4') of the PSA (Prefix Storage Area). General register
6 contains the address of the active RCHBLOK. Examine the following
fields:
1. The real channel address is found in the RCHADD field (displacement X'OO') 2. The value of the RCHSTAT field (displacement X'04') describes the
status of the real channel. Value of RCHSTAT Comments X'80'--ChanneI-busy X'40' lOB scheduled on channel X'20' Channel disabled X'01' Channel dedicated
3. The value of the RCHTYPE field (displacement X'05') describes the
real channel type: Value of X'80' Selector channel X'40' Block multiplexer channel X'20' Byte multiplexer channel X'01' S/370 type channel (S/370 instruction sUFport) 4. The RCHFIOB field (displacement X'08') is the pointer to the first IOBLOK in the queue and the RCHLIOB field (displacement X'OC') is
the pointer to the last IOBLOK in the queue.
The address of the first RCUBLOK is found in the
(displacement X'3BS') of the PSA. General register 7
current RCUBLOK. Examine the following fields: ARlOCU field
points to the 1. The RCUADD field (displacement X'OO') contains the real control
unit address.
2. The value of the RCUSTAT field (displacement X'04') describes the
status of the control unit:
3. 4. 5.
6.
7. S. Value of RCUSTAT X'SO,-- X'40' X'20' X'OS' X'04' X'02' X' 0 l' Comllents Contror-unit busy lOB scheduled On control unit
Control unit disabled RCUCHA to RCHBLOK path not available RCUCHB to RCHBLOK path not available RCUCHC to RCHBLOK path not available RCUCHD to RCHBLOK path not available RCUCHA (displacement 1'10') points to the Primary RCHBLOK. RCUCHB (displacement 1
1
14')
points to the first alternate RCHELOK. RCUCHC (displacement I'1S') points to the second altsrnate RCHBLOK. RCUCHD (displacement X' 1C') points to the third alternate RCHBLOK.
The value of the RCUTYPE field (displacement X' 05') describes the
type of the real control unit:
Comments Value of RCUTYPE X'SO'-- ThiS-Control unit can attach
Subordinate control unit
to only one subchannel X'40' X' 0 l' X'02' X'03' TCU is a 2701 TCU is a 2702 TCU is a 2703
The RCUFlOB field (displacement I'OS') points to
in the queue and the RCULIOB field (displacement
the last lOBLOK in the queue.
the first IOBLCK X'OC') points to
The address of the first RDEVBLOK is found in the ARIODV field
(displacement X'3BC') of the PSA. General register 8 points to the
current RDEVBLOK. Also, the VDEVREAL field X'24') of each YDEVBLOK contains the address of the associated RDEVBLOK. Examine the
following fields of the RDEVBLOK: 1. The RDEVADD field (displacement X'OO') contains the real device
address. Part 1. Debugging with V"/370 57
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