Thanks. Sehr freundlich. (I am still responding to a presumption about my
name in another thread.)
This brought to mind a fairly long running discussion, from a few years
ago, that never came to a definitive conclusion. (That you probably
know the answer to).
Why was the 7400 TTL power supply 5+/-5% volts?
No idea. I do remember that DTL ran on 5, DTL was standard before TTL (and
many firms designed their TTL families to interoperate and intermarket with
their established TTL -- Fairchild "CCSL" 3000 series and so on). And that
RTL like Fairchild's uL900, 914, 923, 926 (I think I still have some of
those in my Junk Box), as already cited, around 3.6V. The commercially
successful DEC discrete-component logic PCB's, une of many things nicknamed
over the years "flip chips" (R series -- red -- "2 MHz;" W series --
white -- "10 MHz") used in some versions of the seminal PDP8 and other
computers -- had *if memory serves* 0 and -3V logic levels and multiple
supplies including +10V, the logic based on PNP discretes.
We received a couple of PDP5's -- predecessor to PDP8, larger -- for the
Berkeley Computer Club when I was an undergraduate there in the middle
1970s. They were not functional and neither were we, by which I mean that
none of us students had time to repair them. A few of us students (not I)
had discovered the Internet then and one of us students achieved the
doubtful distinction of arrest by FBI for some of the earliest hacking into
forbidden sites, a story in its own right with spicy elements that I'll save
for in person some time. (I do like good stories.) Here's another good one
anyway. The two PDP5's stood idle in our basement office in the student
union building, an office we'd obtained along with funds (used for a public
educational program) through the skills of the founder (or restarter
actually) of the club, who had instinctive political ability, and maneuvered
to get annually for us a slice of the ASUC budget that was eagerly contested
among very many student organizations, many of them political and (to my
unsophisticated eyes) similar looking. But as it happens our little office
was located right between those of the (Trotskyist) Spartacus Youth League
and the (Stalinist) Revolutionary Communist Youth Brigade, high-profile
bitter rivals always suspicious of each other. (At the time, newspapers
reported one of the groups, sporting rakish red berets -- very revolutionary
looking -- having meetings that got broken up by the other group showing up,
uninvited, carrying axe handles. That's how it was. I didn't know these
groups well but from appearance and statements I got the impression that
most of the members were middle-class suburban college kids, some of them
probably from well-off families. It is often so. That was not my own
background by the way, my parents had been "beatniks" in the 1950s, trained
in fine arts and hung out with a bohemian crowd that included various
Wobblies and Communists and Lincoln-Brigade veterans but there I go, getting
off track again.) Anyway, one of our Computer Club members, the same one
who got the attentions of the FBI, had a fine idea for the idle computers,
which though inactive were formidable looking. They stood against a wall
facing the door of the little office so you could see them from the partial
glass in the door. The mischievous member posted a sign inside the door
glass, leaving the computers visible, that "Both computers are on loan to
the Campus Surveillance Project" -- there was of course no such nonsense,
but the SYL and RCYB could be reasonably relied on to not know that (it is
often so) and to get paranoid about this operation right between their own
two offices. The note went on to refer curious members to a Sergeant
so-and-so of the Campus Police with a contact number that was, I believe,
one of the handy local TelCo test numbers, a busy-beep generator probably.
Hoped to offer the intrepid comrades some mild distraction from beating each
other up.
Have a follow-up account of early voltage standards but one story at a time.
Max
I did find EER amplifiers tho, and posted under I think
