ATT System 25 Reference Manual

HARDWARE DESCRIPTION
HARDWARE DESCRIPTION
This Section provides descriptions of System 25 hardware components and their functions.
The hardware is covered under the following major headings:
l System Cabinets:Includes circuit pack (CP) carriers, power supplies, wiring, and
cooling equipment.
l Circuit Packs: Includes detailed information on CPs.
l Terminal Equipment:Equipment that can be connected to voice or data station
ports.
l Peripheral Equipment: Equipment that can be connected to the CPU/MEM CP.
l...

HARDWARE DESCRIPTION
The cabinets have a brown front cover with beige top and sides. The front cover has a
system identification stripe across the top.The top has four indentations to facilitate the
stacking of cabinets.
Each cabinet is constructed of sheet metal and is 13 inches high, 17 inches wide, and 21
inches deep and weighs about 75 pounds fully loaded.A 3-cabinet system occupies a
vertical space of about 40 inches.It is recommended that the cabinets be placed on a desk-
or table-top. They must...

HARDWARE DESCRIPTION
—
—
—CABINET 3
(12 PORT CIRCUIT PACKS)
CABINET 2
(12 PORT CIRCUIT PACKS)
CABINET 1
(CONTROL AND SERVICE
CIRCUITS; 10 PORT
CIRCUIT PACKS)
Figure 4-1.
System 25 Cabinets (J58901A)—3-Cabinet System
4-3 

HARDWARE DESCRIPTION
CAUTION & WARNINGGROUNDING
LABELSFCC LABELBLOCK
SYSTEM 25
VOLTS AC
J58901A
AMPS
HZ
25-PAIR
CONNECTORSINPUTON/OFF
AC POWERSWITCH
RECEPTACLE
Figure 4-2.
System Cabinet (J58901A)—Rear View
Cabinet 1 (Control and Port Circuits)
Cabinet 1 (Figure 4-3) is always required.It provides mounting space for 12 CPs and can
support a small telecommunications system (for example, 50 to 60 stations and 10 to 15
trunks.)
Cabinet 1 contains the CPU/MEM CP and the Service Circuit, which must be mounted...

HARDWARE DESCRIPTION
POWER SUPPLY
1
23
45
67
89101112
PORT CIRCUITS
POWER SUPPLY
CIRCUIT PACK SLOTS
CPU/MEMSERVICE CIRCUIT
CABINET 1—MOUNTING FOR CONTROL & PORT CIRCUIT PACKS
CIRCUIT PACK SLOTS
12
34
5
6789101112
PORT CIRCUITS
CABINET 2 OR 3—MOUNTING FOR PORT CIRCUIT PACKS
NOTES:
1.
2.
3.4.
5.
6.
REFER TO TECHNICAL SPECIFICATIONS, SECTION 5 FOR CIRCUIT PACK UNIT LOAD INFORMATION.DIVIDE THE TOTAL NUMBER OF VOICE TERMINAL AND TRUNK CIRCUIT PACKS BETWEEN THE CABINETS
USED.
MOUNT VOICE TERMINAL CIRCUIT PACKS...

HARDWARE DESCRIPTION
Cabinet Address Plug
An address plug is provided on the middle of the backplane of each cabinet (accessible after
removing the top rear cover) and is used to designate the cabinet number to the software. When
address plug is plugged into the designated area at CP slot 5, the cabinet is identified as Cabinet 1
at slot 6 as Cabinet 2, and at slot 7 as Cabinet 3.
*
†
Table 4-A. Total Port Circuit Packs Per System
NUMBERPORTTOTAL PORT
OFCABINETCIRCUIT
CIRCUIT
CABINETSNUMBER *
PACKSPACKS...

HARDWARE DESCRIPTION
Circuit Packs
This part describes required and optional System 25 Circuit Packs (CPs) and their compatibility and
features. Required CPs are the CPU/MEM and the Service Circuit. Optional CPs are the Station
Port CPs, Trunk Port CPs, Pooled Modems, and Tone Detectors; the latter two CPs, plus the
Service Circuit, are also classified as System Resources. Table 4-B lists the CPs of System 25. For
more detailed functional descriptions of the CPs, refer to Section 3 of this manual.
Table...

HARDWARE DESCRIPTION
Required Circuit Packs
The following CPs are provided with all Release 3 systems and must be mounted in Cabinet 1:
l ZTN142 CPU/MEM (Call Processing Unit/Memory)
The ZTN142 (one per system) provides a central processing unit, Random-Access Memory
(RAM) (memory) for call and feature processing, interrupt controller, programmable timers,
real time clock, status display, processor bus interface, and four interface ports. It also
provides Read-Only Memory (ROM) for translations and a...

HARDWARE DESCRIPTION
Optional Circuit Packs
The following CPS are optional and can be mounted in any slot not occupied by the required CPS.
Station Port Circuit Packs
l TN726 Data Line
Provides eight ports for Asynchronous Data Units (ADUs). Used for in-building service
within 2000 feet of the system cabinets. Data speeds from 300 bps to 19.2 Kbps are
supported. Service beyond 2000 feet at less than 19.2 Kbps is supported; see Section 5
“Technical Specifications.”Extends a serial communications link from...

HARDWARE DESCRIPTION
Provides eight ports for MERLIN® Communications System voice terminals and ATL
cordless telephones. Used for service within 2000 feet of the system cabinets; ATL cordless
telephones and corded multiline voice terminals more than 1000 feet from the system
cabinet require local power. Off-premises extensions are not supported, Out-of-Building
stations require In-Range Out-of-Building (IROB) units.
l ZTN84 STARLAN Interface
Provides one physical port for interface with AT&T STARLAN...