"Back in the day" of the late 1950's and earlier 1960's, a telephone line and a radio
provided connections to the world of news and entertainment. In and near larger cities, television
antennas provided another connection – for part of the day. Television stations went
"off the air" at midnight, replacing the broadcast signal with a test pattern, and many
(perhaps most) of the television receivers were black and white.
The world is a bit different now, 50 or 60 years later.
The engineers who created the Internet remember when telephones had rotary dials. Some of us
know the signalling details of dialing a number; most know when Area Codes were first assigned, to allow
long-distance calling without talking to an operator. 'DTMF' – Dual-Tone,
Multi-Frequency – added choices, reduced dialing time and tempted the first 'Hackers'.
The details all have a back story, with
lots of interacting requirements and limits and technical choices, every step of the long path from
voice-only telephone lines to the World Wide Web over fiber optics or coaxial cable or wireless, at
speeds up to hundreds of megabits per second.
Been there – Did that . . .
- 1965 Summer - Pelham, New York
- Still in high school, Zenith black & white television at home. Home-brew
short-wave radio receiver in the attic, listening on public safety bands and amateur 4M and 2M bands.
Standard black dial telephone, PE 8-4044.
- 1966 Summer - New York City
|| Graduated from high school, working at a summer job in New York City. Learned
to use an IBM 1050 terminal – 134.5 bits per
second (bps), poll-response protocol over a multi-drop leased line, connected to an experimental interactive
computer system (M44/44X) at
IBM Research in Yorktown, New York.
- 1966–1967 - Freshman Year at MIT
- Wandering after hours, learned to operate the IBM punch-card equipment, the IBM 1401 system used
to prepare batch jobs for the IBM 7094, and the IBM 2741 and Teletype® terminals connected to the
MIT Compatible Time-Sharing System (CTSS).
The IBM System/360 Model 65 running OS/360 used magnetic tapes and punched cards.
|| The 2741 terminals for CTSS were connected to the IBM 7094 at 134.5 bps, using a 7-bit
IBM line code for the Selectric® mechanism. The IBM 7750 communications controller and the MIT
PDP-1 also supported Teletype® terminals running at 110 bps with 7-bit ASCII (IA5) coding.
- On one notable occasion, an MIT instructor called into the CTSS system from England, using a trans-Atlantic
voice grade connection. The Telex network provided very long distance connections at 50 baud, using
5-bit IA2 coding to get 10 characters per second.
- 1967 Summer - Cambridge, Mass.
- Worked as an operating system programmer at the MIT Computation Center, mostly in the machine room
or directly connected to the CTSS system. The IBM
ASP/360 software that Fred Abramson and I were working on interconnected two IBM System/360 machines,
locally, over a Channel-to-Channel Adapter (CTCA) running at about 1.5 megabytes per second.
The I/O cables were a bundle of shielded coaxial wires, over an inch in diameter.
- 1967–1968 - Sophomore Year at MIT
- Continued my part-time work at the MIT Computation Center doing user support, miscellaneous programming
and librarian duties for the SHARE User Group software distributions.
- 1968 Fall - Junior Year at MIT
- Started a part-time position with the IBM
Cambridge Scientific Center in Tech Square, across Main Street from MIT. Interactive systems
at IBM were based on CP-67/CMS, using IBM 2741 terminals both locally, via acoustic couplers over voice
telephone lines, and via dial-up modems over the IBM tie-line network.
- Working with Ed Hendricks,
experimented with and developed support for synchronous data communications at 2000-2400 bps,
using IBM Binary Synchronous Communications (BSC) between CP-67 and an IBM 1130.
- 1968–1971 - IBM Cambridge Scientific Center
- Left school and continued with IBM as a full-time employee. Communications over voice-grade
lines were typically limited to 2400 bps, though multi-channel and faster modems started to allow up to
9600 bps. Dedicated lines could operate at speeds up to 56 Kbps using V.35 or proprietary interfaces.
- For our early experiments, Fritz Giesin put together a 2400 bps modem eliminator so we could exchange
data between the System/360 on the second floor and the IBM 1130 on the fourth. For one confusing bug,
we had to use an analog strip recorder (ink on paper) to verify the actual mark/space signals on the wire.
- 1971–1972 - IBM CP-67/CMS Development
- IBM 2741 terminals were locally connected, but one time I dragged a "portable" terminal (full
size Selectric, light blue hard case, built-in acoustic coupler, 30 pounds or so) home to the Putnam Avenue
house in Cambridge.  My housemates thought nothing of it, until I sat back and the 'typewriter'
starting writing on its own.
- 1973–1976 - IBM VM/370 Development
|| Display terminals – IBM 3270s, 26 lines of 80 chars, mostly – were the instruments of
choice. They were connected to a cluster controller by coaxial cables running at 1.5 Mbps.
The controller was connected to the computer either locally via the byte multiplexer channel or remotely over a
2400 to 9600 bps binary synchronous (BSC) line, running a poll-response protocol.
- 1976–1978 - Digital Equipment (DEC)
||The Distributed Systems group was located on ML5-5, the fifth floor of building 5 in the
Civil War era woolen mill complex in Maynard, Mass. The terminals were locally connected at 2400-9600 bps,
I think, via 20-ma current loop interfaces. Current loop was a version of the very old Telex network wiring,
useful because it avoided the wire-length limitations of RS-232C without the cost of coaxial cables.
- The communications software that I was developing for DEC provided support for the IBM Systems Network Architecture
(SNA) protocols, using an SDLC / HDLC interface that operated at up to 19.2 Kbps. Typical computer-to-computer
networking (DECnet) ran over synchronous lines at similar speeds, if I remember right. Terminal traffic most
often was limited to 9600 bps over various interfaces.
- 1978–1979 - Cambridge Telecommunications (CTX)
- CTX was a small company startup with network interface software for the IBM 3704 and 3705 communications
controllers, providing terminal support across networks such as X.25, CitiNet, Datapac, Tymnet and Telenet.
Terminal connections ran at 110 to 1200 bps over dial-in lines to a concentrator (PAD - Packet Assembler
and Disassembler) - then multiplexed over synchronous leased lines at speeds of 9600 bps to 19.2 Kbps.
CTX developed a remote terminal concentrator for dial-in terminals, based on Zilog Z80 microprocessors.
- 1979–1985 - GTE Telenet Communications
- CTX was purchased by Telenet Communications a year after I joined, which was a few months after Telenet had
been acquired by GTE Corp. GTE Telenet provided X.21 and other terminal protocols over a backbone X.25
virtual circuit network. Working with other network service providers – Datapac, Memorex, Tymnet,
Citibank and larger IBM customers – Telenet developed virtual circuit support for a variety of terminal
protocols. Network backbone speeds were 56K to 1.544M bps (T1) for long-haul links.
- 1985–1989 - Prime Computer
- The 1980's was a period of data communications expansion based on minicomputers, workstations and the
new personal computers offered by Apple Computer and IBM. Networks were running over coaxial cable, over
public X.25 services, leased telephone lines, and many other media. Ethernet and TCP/IP became common, as
did AppleTalk and NetWare and PrimeNet.
- 1990–1993 - Ungermann-Bass
- Ethernet and IBM Token Ring and FDDI were the stars of this period. Connectivity on engineered wiring
supported local network speeds of 4 Mbps, 10 Mbps, 16 Mbps and more. Speeds up to 100 Mbps were available
on early fiber optic networks, especially for trunk lines between network wiring hubs and server locations.
Network hubs and wiring closets were the products, but there was also some early FibreChannel technology at data
rates up to 1 Gbps in machine-room locations.
- Business use of data communications was spreading wildly. Ungermann-Bass headquarters and management
software development were in Santa Clara, California; network component engineering groups were in Andover,
Massachusetts and in Boca Raton, Florida. There was a three-way video conference system (by Compression
Labs, Inc.) setup to allow remote meetings, using a pair of dial-up telephone links at 56K bps each.
- 1993–1997 - Augment Systems
- The need for speed had set in. Gigabit machine-room networks connecting storage arrays with processors
were available over both fiber optics and over engineered wiring. Simple AppleTalk at 230 Kbps was still
around because it was very inexpensive, but 10 Mbps Ethernet was most common. The Augment AFX-410 servers
ran over 1 Gbps FibreChannel Arbitrated Loop (FC-AL) for mixed clusters of Apple Macintosh and Windows-NT PCs.
Integrated Services Digital Networking (ISDN) provided higher data rates and new services, based on technology
updates in the 'telco' networks. The Internet and the World Wide Web became available to the general
public at useful speeds. Specialized processors and software dropped the cost of connections dramatically.
- 1997–1998 - VideoServer Connections
- Dialed a live video call at 384 Kbps, from our lab in Marlborough, Massachusetts to the Teletek lab in Taiwan,
via three ISDN Basic Rate interfaces and a prototype end station that cost less than $7000.
- 1999–2000 - NorthStar Internetworking
- Dial-in terminal server for Internet access: up to 24 channels at 56 Kbps over T1 interfaces (U.S.),
up to 31 channels over E1 interfaces (CCITT).
- 2000 - Hammer Technologies
- Multi-channel, multi-protocol data network behavior testing and network simulation at interface rates up to
2.5 Gbps, using custom processors (C-Port C5) in a Compact PCI chassis.
- 2000–2003 - Vivdon & StarBAK
- Multimedia over the Internet, music streaming and video conferencing, based on custom operating system software
and soon-to-be-generic Intel server engines.
- 2003–2004 - Katana Technology (Virtual Iron)
- Distributed virtual multiprocessor with shared memory, in a server cluster exploiting Infiniband at 12 Gbps.
- 2004–2010 - Crossbeam
- High performance network traffic with security policy applications, in redundant network switches handling up
to 40 Gbps aggregate data rates.
- 2011 - SafeNet
- High security network file system (NFS) servers with encryption, using Freescale multicore processors.
- 2011–2012 - Symmetric Computing
- Distributed multiprocessor Linux clusters with very large memory, direct-connect Infiniband at up to 40 Gbps.
- 2012 - VideoIQ
- Analog and digital video encoding with real-time activity analysis for surveillance, 10/100 Mbps Ethernet
with Internet access.
- 2013–2015 - Affirmed Networks
- Subscriber Services and Content Gateway for mobile network providers, using clustered servers with multiple
interfaces at 1-10 Gbps.
- 2015–2016 - Avigilon
- (New corporate parent for VideoIQ technology.) Real-time video analysis and network-edge recording, supporting
10-100 Mbps Ethernet camera network connections and 1 Gbps backbone networks.