PiDIBLOK The PiDIBLOK is used to retain information about invalid passwords sUFFlied with LOGeN and AUTOLOG cemmands.
o
8 10 18
Hexadecimal
Displacement
------------ 0 8
E
14
18 1C 1D
1E
i PiDUSRID I ---------------------------------------------------1 PiDDATE PiDTlftE I ------------------------------------------------------1 PiDTIME (cont.) PitTERftA 1 ---------------------------------------------------1 PiDCBAIN P*1 I P*2 IIIIRESERVED//III Field
Nalle PiDUSRID DS PiDDATE DS PiDTIME DS PiDTERMA DS PiDCBAIN DS PWDINYCT DS PiDFLAGS DS PiDLOG EQU PWDALOG EQU DS CL8 CL6 CL8 CL4 F 1X 1X in PiDFLAGS --X'8'O'-- X'40' XL2 Field Description, Contents, fteaning Userid attellpting LOGON or AUTOLOG Date (Illlddyy) Tille (hh:III1:SS) Terminal address
Address of next PWDIELOK P*1 Invalid password count P*2 Flags
This block for LOGeN This block for AUTOLCG for IBM use
78 IBM VM/370 Data Areas and Control Block Logic

In order devices
requests
several
l:locks
types:
to centrol the activity of the I/O of the system and schedule I/O uFon them, I/O control uses tYFes cf control blocks. These
can l:e separated into two basic • Static blocks that describe the
components of the I/O system. • Dynamic l:lccks that represent active and pending requests for I/O operations.
The I/O cemponents of the real system
are described by one control block for each
channel, control unit, and device available to the control program. Units present but
not represented by control blocks are not
available for either user-initiated or
centrol program-initiated operations.
REAL CHANNEL CONTROL BLOCKS For each channel attached to the system
there exists a Real Channel Control Block (RCHELOK) which contains: • The channel Fortion of the address of
its attached units, • Status flags indicating the channel's ayailability for scheduling. • A two-way queue anchor pointing to the
list of I/O requests waiting to use the
channel.
In additien, each RCHBLOK contains 32
halfword indexes, arranged in ascending
address order, that represent the
displacement into the Real Central Unit table of the control blocks for the control
units attached to the channel. The 32
entries are required because the control
unit address may be made up of five bits
from the unit address. To locate the
control tlock for a given unit:
1. Index into the table
displacement equal
control unit address.
2. Load the index value.
in the RCHBLOK a
to twice the
3. Add the value to the base address of
the Real Control Unit Table. Real I/O Control Blocks BEAL CONTROL UNIT BLCCKS The Real Control Unit Table is composed of Real Control Unit Blocks (RCUBLOK), one for
each control unit on the system. These
blecks are similar to the RCHELOK in that
they contain the control unit portion of
the address and status flags, and a peinter
to a queue of I/O requests. In addition,
the RCUBIOK contains a pointer te the RCEELOK for the channel to which it is
attached. The RCOBLOK ccntains a table of
16 halfwerd entries that represent the
displacment into the Real Device Table of its attached devices. This table is
referenced in the same manner as the table
in the RCEBLOK. REAL DEVICE CCNTROL BLCCKS Each device and 3270 remote communications
line in the system is represented by a Real tevice Control Block (REEVELCK), contains
the device portion of the unit address and
status flags similar to those in RCHBLCK and RCUELCK. There is alse a pointer fer
those operations that are waiting fer the
device to become available. Fields that
appear in the RDEVBLOK and not in the othe';c blocks include a pointer te the I/O that is currently active en the device, SIC counts, and a pointer te error and sense
information. The RDEVELCK contains a
pointer to the RCUELCK for the control unit to which it is attached and fields of
device dependent information which do net
affect the operation of I/C If the RDEVBLOK is associated with 3270 remote communications line, then the REEVELOK contains a pointer to NICBLCKs that represents the resources on that line. INPUT/OUTFUT BLOCKS I/O requests that are active in the system
are represented Input/Output Elocks (ICELOK) • There 1S one ICELOK for each
operation (that is, channel program) to te executed. The IOBLOK is ccnstructed by the
requesting task and contains such
information as: • The identity of the requestor • The address of the channel program to be
executed Section 1. CP Data Areas and Centrel Elocks 79