11 Aug
2014
11 Aug
'14
6:27 p.m.
On 08/11/2014 04:07 PM, Tony Duell wrote:
There are many, although I cna't find any with the
US-style numbers.
Apart from the HR1 (another HV rectivier, on a B7G base), there are
US subminiatures like the CK505 (pentode), CK509 (tirode), CK510
(tetorde), CK512 (pentode), M54 (tetrode), M64 (tetorde), M74
(pentode) and UK subminiatures like the DF66 (pentode), XFW10, XFW20
(both pentodes), DF70 (anotehr pentode), etc.
Well, the CKxxx number are Raytheon, which appear to have very little
rhyme or reason to them--heck, they even cover transistors (CK722).
Which reminds me--there was a gas-filled half-wave rectifier called the
0Y3 (it was distinguished by an extra "starter" electrode). The odd
thing is that 0Y3 is also the part number for a German germanium diode.
IT's not strictly an American number, I think, but
it's the right
format : 2D21. That's what I know as an EN91, a xenon-filled tetrode
thyratron. B7G base and 6.3V heater (of course)
Yup, the miniature version of the 2050. I was thinking of the 2E26 -
sort of a low-power 6146.
Also watch for UK Mazda (ntohign to do wit hthe car
company) valves.
These have a similar format number 9digits, letters, digits) but the
code is totally different. The first digits do give the heater
voltage -- except that 10,20,30 mean for use in series strings of
100,200,300mA. The lettes do give some info about the electrode
stucture -- C = frequency changer, D = diode, F = pentode, L =
triode, P = output penotode, etc.
Yes, but the numbering scheme seems to have been
designed nto to
give useful information
Certainly, as it supplanted the even more confusing 2/3 digit system
(the RCA UX-nnn system), which told you nothing about what the tube was
supposed to do. Contrast, say, a 12 with a 12A. Transmitting tubes
never did get systematic religion.
The name comes from the fact that hte beam forming
plates etc supress
the econdary emision from the anode, so the IA-VA curve doe not have
the negative resistanve part that is forund in the curve of a plain
tetrode.
Never heard the term "kinkless" before. A common source of confusion
was calling these "pentodes", which was a very different thing, as, say
the EL34.
Yes, but there often _is_ a reason for the opcodes, if
you search for
it. For example, in the hP98x0 procesosr, the memory refernce
instructions have the opcode in bits 11...14 of the instruction word.
A simialr set of register-reffernce isntrcutions has the opcode in
bits 7...4 and the opcodoes are essentially the same. It makes sense.
In the microcode, the instruction word (in the Q register) is shfited
to get the opcode bits in the same location, so the same microcode
fork cna be used to decode the instruction. Of coruse there is no
rrason why opcode 000x is load, 001x is compae, etc. You could
reassign those with trivial changes to the mocrdoe.
Good grief, there are plenty of examples of opcodes that make no numeric
sense. Even better are the ones where the opcode itself is a
variable-length bit field. Even in architectures where all opcodes seem
to have been taken, engineers will find a way to fit extras in.
Witness the Rabbit version of the Z80--they appropriated several
do-nothing register moves to add some functionality.
For example the no-op on the CDC Cyber 70 is 46xxx. But by noticing
that the assembler always coded it as 46000, a few new instructions for
the compare/move unit were squeezed in by giving significance to those
extra positions.
--Chuck