COMMTEST.  Communications concurrent 
diagnostic test (procedure). 
See 
also 
BSCTEST, 
SDLCTEST, 
and 
ST 
A TEST. 
completion code. 
See 
condition code. 
condition code.  A code that shows the results 
of 
a 
processing operation. 
configure.  To make or describe a configuration. 
control panel.  A panel that contains keys, lights, 
and displays used by the operator (for normal 
operation) and by 
the. 
service representative (for 
system maintenance). 
control storage directory.  An area on disk that 
contains the address 
of 
all programs in the control 
storage library. 
control storage library.  An area on disk 
that 
contains the diagnostic programs that are loaded to 
control storage. 
CRC.  Cyclic redundancy check (character). 
CRQ.  Call request. 
CSP.  Control storage processor. 
CSu. 
Customer setup. 
CTS.  Clear to send. 
customize.  To update the unit definition table and 
system microcode on disk. 
See 
also system 
customize utility. 
cycle steal.  The process by which a device uses 
cycles 
of 
another machine or device.  If, for 
example, the processing unit 
is 
performing an 
ALU 
operation when the disk needs service, the ALU 
operation 
is 
stopped while a byte 
of 
data is moved 
to 
or 
from the disk. 
cyclic redundancy check character.  A character 
code used for error sensing and correction. 
cylinder.  In disk and diskette storage devices, a 
cylinder contains all the data under all heads 
without moving the actuator or the head and 
carriage assembly. 
D-2 
5363 
Maintenance Information 
data set ready.  A communications signal that 
indicates that the modem 
is 
ready to transmit or 
receive data. 
data terminal equipment.  The processing unit that 
uses data communications lines. 
data terminal ready.  An EIAjCCITT interface line 
that signals the modem when the terminal 
is 
ready 
to transmit or receive data. 
dB.  Decibel. 
DBI. 
Data 
bus in. 
dBm.  Decibel based 
on 
one milliwatt. 
DBO. 
Data 
bus out. 
DCE. 
Data 
communications equipment. 
DCP.  Diagnostic control program. 
DDSA.  Digital 
Data 
Service Adapter. 
DE.  Disk enclosure. 
decibel.  A unit 
of 
measure that is the ratio 
of 
two 
power or voltage levels. 
dedicated. 
(1) Pertaining to one application or 
purpose. 
(2) 
A time during maintenance when no 
customer jobs are running. 
defect. 
(1) 
A failure.  (2) A bad area on a disk, 
diskette, 
or 
tape surface.  (3) An error in a released 
program or program module. 
determination. 
See 
problem determination. 
diagnostic control program.  The supervisor program 
that controls diagnostic programs. 
Digital Data Service Adapter.  In data 
communications, a device used in place of a modem 
when transmitting data over the AT&T Digital 
Data 
Service Network.  (A DDSA can also 
be 
used 
for local connections.) 
directory. 
See 
control storage directory and diskette 
directory. 
disk enclosure.  The sealed unit 
of 
the disk storage 
device 
that 
contains the disks, the spindle, and the 
actuator.