Colour Display System SEMIGRAF 240 - The history of Ericsson

System data for AXB 20
Application
All electronic, stored program controlled system
intended as a combined local and transit exchange
for both national and international telex
and asynchronous data traffic.
Since the system is used predominantly for telex
traffic, the data given below have been limited to
the telex application.
Multiple capacity
30 480 subscriber lines and/or trunk lines.
Call capacity
Approximately 60 calls per second.
TDM switching matrix
Regenerating, bit-oriented time division multiplex
matrix which is free from congestion The reception
margin is better than 46 %.
Data transmission speed
50 bauds (up to 300 bauds for asynchronous data
traffic).
Line connection modes
Single current, double current, frequency shift
signalling.
TB voltages
±12 V, +30 V. +50 V, +60 V, ±80 V, start polarity
+ or -.
Signalling variants
CCITTRec. U.1 type A and B, U 11 type C, U.12
typeD, U,20 and X.70.
Selection method
Keyboard or keyboard/dial selection.
Service signals
OCC, DER, NC, GA, MOM, NCH, ABS, NP etc. and
time information as the proceed-to-select signal.
Operator service
The switching system permits the connection of
operators' positions, equipped with display units,
for manual assistance in the setting up of calls.
Numbering
Free choice of subscriber numbers for each line
connection circuit, and also free choice of line
and route number for each connection circuit.
Redundancy
All traffic handling units in the exchange are duplicated
and work in a parallel synchronous
mode.
Processors
Synchronously duplicated central processor.
Regional processors for simple tasks.
Memory capacity (with maximum capacity)
Program store 1024 k words (16 bits)
Data store 1024 k words (16 bits)
Reference store 64 k words (32 bits)
Rack dimensions
Height 2250 mm (6 shelves) or
2900 mm (8 shelves)
Depth 620 mm (mounted back to back)
References
1. Strindlund, E. et al.: AXB 20 - All
Electronic, Stored-Program Controlled
System for Telex and Asynchronous
Data Traffic. Ericsson
Rev. 54 (1977):1, pp. 32^10.
2. Strindlund, E. et al.: AXB 20 - Description
of System. Ericsson Rev
54 (1977):1, pp. 41-51.