Disk Drives Overview; Disk Drive System Description; Disk Drive Start-Up - Northern Telecom DMS-100 Series Maintenance Manual

Disk drives overview

Disk drive system description

The DPP uses two hard (fixed) 5-1/4 inch disk drives in the lower left corner
of each processor chassis. These drives are mounted on brackets ( Fig. 3-1).
In the 380- and 760-Mbyte drive, the controller is an integral part of the disk
drive assembly. For the 72- and 140-Mbyte disk drives, ribbon cables are
factory installed between the disk controller PCA and disk drive unit.
The DPP is configured as a disk-based system. That is, the main programs
for system operation are resident on disk. The programs are automatically
retrieved from disk and loaded to the Extended Memory (DRAM) PCA and
the 56K Interface (if equipped) upon power-up. Programs are retained on
disk as archives in case the processor(s) require a reboot. The DPP system
can be downloaded with new programs from the DMS-100.

Disk drive start-up

When the DPP system is powered up, either during initial installation or
after maintenance, closely watch the printouts. These messages provide
information as to the initial condition of the DPP and direct the next course
of action. Two important printouts may occur within the first 60 seconds.
The first is:
S/W LOADED
The second is:
DISK MODE: (This message defines the DPP's ability to access the disk drives. Disk
(The main program is successfully loaded from disk to processor RAM
and primary system functions can begin.)
mode operating conditions are defined in Table 3-1)
where:
xx = AO = A ONLY
= AP = A PRIME
= BO = B ONLY
= BP = B PRIME
= NONE = NO Disk Mode
Note: The S/W LOADED message cannot print if DISK MODE: NONE is
printed.
DPP Recovery and Routine Maintenance Guide BCS35 and up
3-1
.