16 System architecture
Both types of Mass Storage Unit (MSU) are compatible with any Meridian
1 system running Software Generic Xl 1 Release 8 or later. The upgrade
procedure involves replacing the Magnetic Tape Transport and associated
tape interface with the desired Mass Storage Unit and equivalent Mass
Storage Interface card (MSI) or Floppy Disk Interface (FDI) card. The
Mass Storage Unit requires the identical space required for the magnetic
tape unit, See
Disk drive
upgrade procedures
(553-3001-251) for more
information about disk drive upgrades.
Input
/
Output (I/O)
llnterfaces
There are various methods of communicating with Meridian 1 systems. A
family of Serial Data Interface (SDI) circuit cards provides from one to four
communication channels which conform to EIA Data Interchange Standard
RS-232-C. I/O addressing is under switch control of the
SD1
card and
allows up to 16 RS-232-C compatible devices, such as a terminals, to
communicate with the system. The devices are used to input commands
and/or receive responses from the system during administration and
maintenance procedures.
Memory
Firmware, software, and data are stored in a read/write Random Access
Memory (RAM). The memory is a critical part of the stored program
control system. It contains the memory stores of all of the basic operating
instructions for the system, plus data on the configuration of the particular
application being served. Memory utilization is dependent upon what
features are programmed into the system and the number of peripheral
terminations being served. The memory is split into four segments to
facilitate processor address purposes and permit a functional separation of
programs.
-
Unprotected Data Store
(LIDS):
These pages hold the transient or
unprotected data that is required during call processing. Included are
the timing queues and call registers.
-
Protected Data Store (PDS) : This protected data store holds the office
data blocks that are particular to specific installations.
Program Store (PS): Allocations within the Program Store are as
i.
-
:
.~
:.,
-..
a
follows:
:
.-a
./
System overview 553-3001-I 00
c