____________________________________________________________________________
| |
| "Peering into the Soul of ESS - The Master Control Center" |
| |
| Written By - Jack The Ripper |
| |
| Organized Crime (OC) |
| Phile #2 of P/HUN Magazine Issue #5 |
|____________________________________________________________________________|
The Master Control Center is undoubtably the very essence of ESS. The
Master Control Center (MCC) is the operational, maintenance, and administrative
core of the electronic switching central office. This unit is what the ESS
operators use to control the ESS switch. It test's customer lines and trunks,
alarms to indicate malfunctions, perfroms system testing functions, controls
operations, contains the magnetic tapes for recording Automatic Message
Accounting (AMA) data, and contains various other specialized equipment.
Primary Components of the MCC
-----------------------------
Master Control Console
Trunk and Line Test Facilities
Teletype (Teletypewriter) Channels
AMA Recorders
DATASPEED -40 Terminal with Display and Printer
[---------------------------------------------------------------------------]
[ Diagram of Processor Display Panel of Master Control Console in No.1A ESS ]
[---------------------------------------------------------------------------]
_______________________________________________________________________________
| Processor Display | PS Bus | Pu Bus | CS Bus | AU Bus |
| | Ad Re Ad Re| Ad Re Ad Re| Ad Re Ad Re| Ad Re Ad Re|
-------------------------------------------------------------------------------
|_____________________________________________________________________________|
||CC0 | ac| tr| po| st| of|| 0| 0| 1| 1|| 0| 0| 1| 1|| 0| 0| 1| 1|| 0| 0| 1| 1|
||----------------------------------------------------------------------------|
|| ltllh |====================================================================|
||-------|--------------------------------------------------------------------|
|| ltllh |====================================================================|
||____________________________________________________________________________|
||CC1 | ac| tr| po| st| of|| 0| 0| 1| 1|| 0| 0| 1| 1|| 0| 0| 1| 1|| 0| 0| 1| 1|
||----------------------------------------------------------------------------|
|| || || || || |
|| -------------------------------------------------------- |
|| |meno|kc || ||meno|kc || || |
|| |------------||___________||------------||___________||------------|
|| |02| |36|ntce|| 0! 0! 1| 1||02| |05|ntce|| 0| 0| 1| 1||fs|df|ft|df2|
|| -------------------------------------------------------------------|
|| | || || || |
|| | seno || || seno || |
|| | ---- ----|| || ---- ----|| |
|| |ps|0|2| |ii || ||ps|0|2| |lh || |
|| | ----- ----|| || ----- ----|| |
||----------------------------------------------------------------------------|
|| Update || OverRide Control || SysR || Processor Configuration Seq. |
|| || || || state counter |
|| ----- ||------------ -----||-----------||--------------- ----- |
|| |inp| ||bl|au|ps|cc| | no ||rea|ena|err||p3|p1|8|4|2|1|| |rec| |
|| ----- ||------------ -----||-----------||--------------- ----- |
|| ----- ||------------ || || |
|| |fs0| ||vr|a1|p2|c1| ||___________|| |
|| ----- ||------------ || || |
|| ----- || Activate|| ||Activate |
|| |fs1| || ---- ---- || ----- ||------ ------------------|
|| ----- || |x1| |x2| || |inv| ||q1|q2| |w1|w2|w3|w4|w5|w6|
|| || ---- ---- || ----- ||------ ------------------|
|| || || || |
||_________||__________________||___________||________________________________|
Key
---
w6 = Prssr Comfg
w5 = Prgm Store
w4 = Call Store
w3 = Basic Prssr
w2 = Reptd Pc
w1 = Pc Atmpt
x2 = Ovrd Efct
x1 = Vrbl PS1
q2 = Dsble Auto
q1 = PC
fs1 = FS 163
c1 = CC1
p2 = PS Bus 1
a1 = AU Bus 1
vr = Vrbl PS 0
fs0 = FS 062
rec = Reset Cntr
p1 = Pmp 16
p3 = Pmp 32
err = Error
ena = Enable Data
rea = ready
no = No Ovrd
cc = CC D
ps = PS Bus 0
au = Au Bus 0
bl = Blk 0 Ps 0
inp = In Prgs
SysR = System Reinitialization
lh = LHIJI
ii = IIOLI
seno = Select No. (Select Number)
df2 = Disk File 1
ft = FS 1 Trbl
df = Disk File 0
fs = FS 0 Trbl
meno = Member Number
kc = K-Code
|| = Separates different Status Bars ie PS Bus, Processor Display, and Au Bus
ac = Active
tr = Trble
po = Power
st = Stop
of = Offline
+++ Added note on the key is that the abbreviations on the key are exactly the
same as they appear on the panel.
As you can see the MCC panel is divided up into five main groups of
keys and lighted or LED displays; processor display, update, override control,
system reinitialization, and processor configuration sequencer. The update
group of keys and displays permits personnel to check when a program update is
in progress. The override group of switchs and displays allows personnel to
manually activate a central control unit, auxillary bus unit, and program store
buse for emergency system recovery. The system reinitialization keys and
displays allow personnel to manually reinitialize the system in conjuction with
the override control or processor configuration sequencer group of keys.
Workings of the MCC and Points of Interest
------------------------------------------
Now that you have a little background information on the MCC, and are
familiar with the MCC Console we can talk about the MCC a little more. The MCC
can be used to remove from service all outgoing trunks, customer lines, and
service circuits. This would be an interesting project next time your at your
local CO to stop all service to an area. The MCC is capable of flagging
pernament signals i.e. busy signal (black box on electromechanical or crossbar
offices) . The master testing circuit can be connected to any outgoing trunk,
service circuit, and most often any customers lines for testing purposes. Also
the MCC can be connected to any voltmeter to test any customers line, service
circuit, or outgoing trunk. The MCC also interacts with Remote Switching
Systems to perform various testing functions to detect bad circuits and
potential future problems i.e. a decaying circuit or two.
AMA in the MCC
--------------
The Automatic Message Accounting recorder is located on the MCC and
stores "customer billing information " on magnetic tapes. One 2,400 ft
reel of tape stores the billing data for 100,000 calls a day. These tapes
however are backed up by duplicates to ensure against failure or billing error
although it does happen, and the two copies are sent to a DPC (Data Processing
Center) for analysis in computing customer bills The data that is to be
stored is selected by the call processing program, which deceides whether or
not the information for a call is to be stored. Then the data is temporarily
stored in the AMA register (full capacity of the AMA register is 230 bits each)
call store, and after completion of the call the related data is assembled in
the BCD (Binary Coded Decimal (see Binary Number System for Decimal Digits
Diagram)) format and placed in the AMA buffer call store.
Binary Number System for Decimal Digits
---------------------------------------
Decimal Four Digit Binary Code
Number A B C D
<8> <4> <2> <1>
-----------------------------------------
0 0 0 0 0
1 0 0 0 1
2 0 0 1 0
3 0 0 1 1
4 0 1 0 0
5 0 1 0 0
6 0 1 1 0
7 0 1 1 1
8 1 0 0 0
9 1 0 0 1
10 1 0 1 0
11 1 0 1 1
12 1 1 0 0
13 1 1 0 1
14 1 1 1 0
15 1 1 1 1
The recording procedure is then started by an AMA program in program
store when the AMA buffer in call store is fully loaded. The AMA buffer has a
full capacity of 140 words of 23 bits each. The AMA program will cause central
control to direct that the data be transferred one word at a time to the AMA
circuit for recording on the tape.
Suggested Reading
-----------------
Basic Carrier Telephony, Third Edition by David Talley
Basic Telephone Switching Systems, Second Edition by David Talley
Anything Else by David Talley he wrote a few more. He is one of the best
telecommunications authors, and all of this information was born into me
through him. His books are also written with quesitons in the back which helps
you to learn the information. Next time some moron throws an infoform at you
asking what ESS is you can quite simply say something rude like, "Are you
talking about the program interruptions in a No.1A ESS office which occur every
1.4 microseconds due to the system clock providing of course that it is running
off of a 1A processor and hasn't been modified in any way, and is running stock
software?" That outta get em eh?
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