Oral History of Robert Everett - Computer History Museum

Oral History of Robert Everett
there’d be a problem, and a decision would have to be made among alternatives. And we’d do all the
homework, and then we’d come in to this 100 people, 100 man meeting, and we’d describe the
alternatives and the pluses and minuses, and how we wanted it, what we thought ought to be done. And
they’d accept. We figured out the major reason they would accept is that none of them wanted to be held
responsible for what was going on if they didn’t. They held us responsible, and that was fine. We were
happy to be responsible. Somebody had to be responsible.
Hendrie: Exactly.
Everett: You can’t…this isn’t the U.S. Congress. Anyway, lots of fun.
Hendrie: Tell me a little bit about the communications side of this. Obviously, lots of digital data going
over telephone lines and presumably eventually had to go over the air to the – probably not initially – the
interceptors were voice controlled initially?
Everett: They were also data links, which Lincoln was involved with.
Hendrie: There were data links? So you could send digital data to the aircraft, even in the earliest
versions of the system?
Everett: There were a couple of different communications systems that the Air Force had. So, well, it was
obvious that it had to go over the telephone lines.
Hendrie: What was the state of the art for doing that?
Everett: There wasn’t any, really. So we, the first thing we did was we had to get a telephone line so we
could do some experiments. So we ordered a telephone line and the telephone company came in and put
the line in, and then they had a handset. And we said, “We don’t need the handset.” They said, “Sorry,
every telephone line comes with a handset.” Anyway, so we built our own digital modems; as I
recall a lot of that was done by Jack Harrington. And so then we had to learn about telephone lines. There
was a question about what kind of data rates you could get. Also it turned out that the telephone lines had
a lot of switching transients in them which didn’t bother people who were talking on them, but it sure
bothered when you sent bits over them. So we had to work with the telephone company to fix these lines
so they didn’t have these sharp signals on them. That had to be done. And at the time of SAGE, they were
all special lines because…
Hendrie: They all had to be conditioned this way.
Everett: Now, we were getting, I don’t know, 1800 bits per second or something across these lines, which
of course is nothing at all today.
CHM Ref: X3877.2007 © 2007 Computer History Museum Page 35 of 56