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Entrepreneurial Capitalism and Innovation:
A History of Computer Communications 1968-1988
By James Pelkey

Entrepreneurial Capitalism & Innovation:
A
History of Computer Communications
1968 -1988
By James Pelkey

This history is organized by three co-evolving market sectors and also standards making.
An overview of the schema is presented in the Introduction.

DATA COMMUNICATON
Ch. 1: Emergence
Ch. 3: Competition
Ch. 5: Market Order
Ch. 11: Adaptation

NETWORKING
Ch. 2: Vision
Ch. 4: Arpanet
Ch. 6: Diffusion
Ch. 7: Emergence
Ch 8: Completion
Ch. 10: Market Order

STANDARDS
Ch. 9: Creation

INTERNETWORKING
Ch. 12: Emergence

 

 

Chapter 11
Data Communications: WANs 1979-1986
Data Networks Become Wide Area Network

 

11.3 The T-1 Multiplexer

T-1 multiplexers interconnect by multiplexing and de-multiplexing many slow speed data and/or digitized voice circuits through a T-1 circuit. The first generation T-1 multiplexers were designed for data circuits, but interconnected digitized voice circuits. Known as point-to-point T-1 multiplexers, they differed radically from the existing paradigm of statistical multiplexers because they could accommodate larger number of input circuits and the digital output circuits fed into channel banks not modems. First generation T-1 multiplexers gave users very little management control. But second generation "networking" T-1 multiplexers gave users first manual, and increasingly automatic, rerouting of circuits; adaptive bandwidth management; flexible configuration of network topologies; reliable system reliable architectures and much more. The history of which firms correctly anticipated how quickly the sophistication of T-1 multiplexers would evolve determined the outcome of market competition and thus those firms that grew and those that did not.

The size and growth rate of the T-1 multiplexer market was directly related to the number of T-1 circuits. Each end of a T-1 circuit, or termination, represented the need for a T-1 multiplexer. The first installations of T-1 circuits were local circuits connecting a corporation’s circuits through a central office (CO) or bypassing the CO and directly interconnecting a corporation’s locations or facilities. Up until around 1985, the demand for T-1 circuits exceeded the ability of the RBOCs to install them and that, in turn, drove the demand for private by-pass networks. (See Exhibit 11.1 T-1 Installed base 1984-1988)[5] By 1988, the importance of private by-pass networks declined as either AT&T/IXCs (Interexchange carriers) or the RBOCs were able to supply the needed T-1 circuits. As the Exhibit shows, the growth in terminations, while somewhat erratic, grew dramatically between 1984 and 1988.

Exhibit 11.1 T-1 Installed Base 1984-1988
(Thousands)

T-1 Terminating Points

1984

1985

1986

1987

1988

Long Haul Via AT&T / IXCs

 

1.4

2.0

3.0

4.0

Local RBOC Intra LATA

 

6.0

9.0

13.0

18.0

Private By-Pass Networks

 

4.0

5.0

7.0

9.0

All T-1 Lines

7.5

11.4

16.0

23.0

31.0

All T-1 Terminations

15.0

22.8

32.0

46.0

62.0

Annual Growth T-1 Terminations

5.0

7.8

9.2

14.0

16.0

Annual Growth Rate T-1 Terminations

 

56%

18%

52%

14%

[5] TBD