The Beginnings of TECO

I came up with the name TECO in 1962 while sitting in Ye Hong Guey, my favorite restaurant in Boston’s Chinatown during my undergraduate years at the Massachusetts Institute of Technology. I had been working on a little program to help me write other programs, a common activity in the day when a computer (the Digital Equipment Corporation PDP-1) would be delivered with almost no software. My program had gotten to the point that it needed a name, so my friend Pete Peterson and I were kicking around possibilities and their acronyms.

Years later, TECO would be known to mean Text Editor and Corrector and so described in its documentation. However, the original meaning—the one we came up with that night at the corner of Oxford and Beach streets—was Tape Editor and Corrector.

Interactive computer use on the PDP-1

We used the term “tape” because punched paper tape was the only medium for the storage of program source on our PDP-1. There was no hard disk, floppy disk, magnetic tape (magtape), or network. There was no operating system, only the paper tape reader and punch and a console typewriter. The paper tape reader was fast (or so it seemed at the time), reading 300 characters per second. The punch was considerably slower at 20 characters per second. The console device was an office-style electric typewriter that had been interfaced to the PDP-1 for character-at-a-time input and output.

The PDP-1 was the first computer built and sold by DEC and thus the leading edge of the minicomputer revolution. It was anything but “mini” by today’s standards, however; it occupied several tall cabinets in its minimum configuration. All that, and it had a main memory of only 4,096 18-bit words (effectively 8 Kbytes). This was core memory made of tiny magnetic toroids strung on thin wires in a 3D mesh. It had a cycle time of 5 microseconds. The processor executed most instructions in two cycles (10 microseconds)—one cycle to fetch the instruction from memory, and the second to load and/or store the memory operand. Some instructions did not reference memory and so required only one cycle.

All this notwithstanding, it was exciting to actually be able to sit at the console and use the computer interactively. My prior experience was with mainframe class machines like the IBM 709 or 7090. Those required preparing a program on punched cards, submitting the deck to the computer center for a batch run, and getting a paper listing of the results the next day. With the PDP-1, the code-compile-debug cycle was shortened from hours to minutes. I could do it several times on the machine in a one-hour session.

In a smart move for a young corporation, DEC had donated a PDP-1 to the Research Laboratory for Electronics (RLE) at MIT, and it was sitting in a room more-or-less available for anyone, including undergraduates, to play with. There were soon many takers. Because only one person could be using the PDP-1 at a time, computer time quickly became scarce, and it was still necessary to do as much program preparation as possible offline. We did this with Frieden Flexowriters, typewriter-like devices with a paper tape reader and punch. Programs had to be handwritten first because editing capabilities on the Flexowriter were nonexistent. The most you could do was nullify a previously punched character by backing up the tape punch and over punching the same line.

Paper tape was more convenient than punched cards in some ways. It was lighter than cards for a given number of lines of program, and if you accidentally dropped it, it did not shuffle all your lines of code. This was also its biggest weakness. When you needed to modify a program—add, change, or delete a few lines—you could not just replace those lines as you did with the cards; you had to punch a whole new tape. Hence, editing on the Flexowriter was a painstaking process of reading an existing source tape and simultaneously punching...