14 Jul
2007
14 Jul
'07
11:16 a.m.
Bob Rosenbloom wrote:
dwight elvey wrote:
The remaining 6 of the decades in the 524's are built with vac-tube flip-flops
as well. Pardon the detail following but there is an interesting point (IMHO):
by count rate there are 3 types of counters in the 524's, the lower speed 6
decades (<=100KHz) are a typical 4 flip-flop circuit built from 4 duo-triodes,
the 1 Mhz counter is similar but with some clamping diodes and lower
resistances, however the 10Mhz stage is about 3 times as complex: 13 tubes
(not duo-triodes), a bazillion clamp diodes, a very different circuit
arrangement and even count sequence.
(FWIW: http://www.cs.ubc.ca/~hilpert/e/edte/HP520.html for my own take on the series.)
It's a good example of the limits of vacuum-tube technology which applied to
the computers of the day (at least with typical tubes in the 50s). Going
beyond a few MHz became infeasible. For references I have at hand the fastest
clock rate I see is 2.5 MHz for BINAC, a lot of the tubes machines seem to
have run at around a MHz or less. Anybody know what the basic clock rates of
the IBM 709 or Sage processors was? (some of the last big tube machines).
Hi Bret
I recall that is was an HP counter. I don't recall the fastest count but
it was on the order of either 10KHz or 100KHz. I don't think it was
less then that but it may have been 1MHz. I recall that like many of the
HP counters of the time, the other decades were the inline 10 ea bulbs. I
don't recall if these were neon or incandescent but I think they were
neons driven by dual triodes. I do believe that the ring counter did
have a purplish glow.
Dwight
I have the manuals for most of the early HP counters. I looked through
them and could not find
dekatrons used. The input goes directly to the counter units. The 523C
goes to 1.2 MHz.
In the 524B counter, there are two divide by 10 circuits built with tube
flip-flops. This
counter counts up to 10 MHz.