How I got into Linux and UNIX

Having dabbled with Fortran and Pascal on Harris H100 and H500 mini-computers, and with Z80 assembler in the CP/M micro teaching lab I managed at Chelsea College, I got my first UNIX user account in 1985 courtesy of a friend - a dial-up account via a 1200 baud modem to an AT&T Bleasdale 3B2 mini-computer in an office off the Brompton Road. Frankly, I wasn't terribly impressed at the time, probably because I couldn't do anything useful with it and UNIX commands seemed so arcane then. I mean, with CP/M and MS-DOS computers you could write letters - theses even - and print them out, program hydraulic robots, do lots of fun things with BBCBASIC(86), get your household finances and telephone numbers organised with dBase2, etc. But an invisible computer far away on the end of a phone line? It just wasn't the same as having a real computer whirring away on your desk.

It was to be another 8 years before I encountered Linux - at the time MS-DOS 5 and Windows 3.1 were all the rage in the desktop PC world but that largely passed me by; in the early Nineties I was holed up in an electronics lab surrounded by logic analysers & oscilloscopes doing a lot of Z80, 8086 and 68000 assembler programming for the various lab computer interface cards I was developing for Queen Elizabeth College in Kensington, including the PC ISA bus, S-100 and G96 industrial buses. Windows was far too slow for any real-time laboratory computing so I stayed with assembler on DOS. Real nerdy stuff and great fun!

At around this time I became an early user of Demon's fledgling 'Ten pounds a month' dial-up Internet service for email, ftp and gopher services - most early subscribers were real UNIX types since DOS, Windows and Macs at that time did not have any networking facilities. UNIX was beginning to look very attractive now but it was horrendously expensive. Then I discovered some Demon MS-DOS users were using a network operating system called KA9Q NOS, which added TCP/IP networking features and more to DOS with a rather UNIX-like command interface. I had a great deal of fun with this and this led to me setting up King's College's first FTP server in my office on the Kensington campus using KA9Q NOS on a 386 PC. At that time, all desktop computers there were stand-alone, there was no network anywhere in the college (only ASCII terminals connected by 9600 baud serial lines via Camtec PADs to the local VAX) and only half a dozen or so privileged users in the central computer centre in the Strand had access to JANET's experimental implementation of the Internet over X25 serial terminal lines.

Known as 'pandemonium' and accessible only through a dial-up modem on my office phone line in the early days, this strictly unofficial FTP server supported ordinary serial file transfers using Kermit as well as SLIP (Serial Line Internet Protocol) and contained early MS-DOS and Windows Internet software. It became very popular - using Xmodem or Lancaster University's Kermit, users could download dial-up SLIP/PPP internet software, email clients, browsers, etc and install it on their PCs in college or at home to make them Internet capable (it wasn't until Windows 95 was released with its built-in support for dial-up networking that the Internet became the mass-market phenomenon it is now).

Eventually the-powers-that-be at the main Strand campus sat up and took notice and it wasn't long before I was offered the job of setting up the college's first dial-up Internet service in 1993 and then later, in 1995, assembling a small team of technicians to roll out Ethernet networking everywhere and getting the entire college on-line. This lead to a seismic shift in my life; my career in electronics design and low level programming ended abruptly at that point as I jumped into the brave new world of computer networking (and eventually, large scale Linux/UNIX systems admin). But that's another story.

It was through a CIX bulletin board one day in 1993 that I first heard of Linux and thought: this is too good to be true - it's got to be better than DOS + KA9Q NOS and the idea of having a UNIX-like computer on my desk or at home for the price of a box of floppies was a no-brainer. And so I ended up downloading nine 3.5 inch floppies and installing Slackware Linux 1.0 on a spare PC; I have not looked back since.

Meanwhile King's dial-up Internet service was a great success, with 18 phone lines in a hunt group feeding into a US Robotics Total Control rackmount modem bank supporting all modem speeds up to V.90 (64 kbit/s), and a Xyplex terminal server to handle SLIP (and later, PPP) connections. It was soon decided to offer secure access facilities for VIP users (eg, the principal, senior admin staff, etc) who already had the luxury of dial-back accounts, where after dialling in and identifying themselves, the connection would drop and they'd be dialled back one minute later at their home phone number. For more security, a random token-based security system called SecureID was later added, where users were given a credit card-sized device which displayed a 6 digit number that updated every 60 seconds which had to be typed in when making the initial dial-up connection. This number was compared with a similar number generated on the SecureID server and a successful match caused the the line to be dropped and the user called back. The SecureID server had to be hosted on a Solaris platform - a Sun SparcStation 4 was duly purchased and so I moved onto Solaris 2.3.

Funnily enough, the hostname pandemonium.cc.kcl.ac.uk is still registered in DNS!

Andy Thomas

Research Computing Manager,
Department of Mathematics
Imperial College London

last updated: 3.03.21