On 2015-Feb-09, at 12:16 AM, Holm Tiffe wrote:
Brent Hilpert wrote:
[..]
Pete clarified your potentially misleading statement. He wasn't "pissing on your
feet".
Sometimes Holm, attempts at redemption just result in digging yourself in deeper.
Soso.
I wrote a statement to how exactly test an 74S240, Pete and you wrote
other, in this casenot interesting things.
It seems that the sentence "all was already sayd, but not from me" fits
well here.
The sentences from TI are right and known to me, bute none of them applies
for a functional check of exactly the 74S240 on the M8186 board.
Connecting the input of the 74S240 wit an R to Vcc to check the High pegel
is simply nonsense.
Holm, I was going to just drop this, but you've now added yet another misleading
statement which needs correction.
You certainly haven't described how to "exactly test" a TTL input, and
pulling the input-under-test actively high is certainly not "nonsense". Pulling
the input high is well warranted in the context of the OP's situation (which you
insist on limiting the matter to), and would indeed be necessary in a complete test of the
input.
Active-high and open-circuit for a TTL input are electronically not the same thing and one
could well conceive of a fault (such as junction breakdown/short with applied voltage) in
which the input behaved as OK when open-circuit, but failed when pulled high.
Add to this that the input-under-test actually is pulled high in-situ (by the oscillator
output), it is even more warranted to test it as such to more closely mimic the in-situ
operation.
The objective of testing is not just to check that the inverter output follows the input
appropriately, but to check the input isn't failing in such a manner as to upset or
damage the oscillator output.
More complete testing would check the current flow through the input, which I would have
got to with the OP if it had become warranted after further examination.
Your initial comment in this thread was itself an interjection to my response to the OP to
pull it high & low. If I had been overly sensitive in the manner of interpreting your
comment I could have taken offense, but I didn't, and I didn't argue with it at
the time. But as per above, it can well be considered as utterly inadequate even in the
limited context for which you claim it was intended.
You have been telling others that their additional commentary and clarifications -
presented for more comprehensive understanding for others - are "wrong" and
"not interesting" when they have been right and you are the one who has been
repeatedly wrong.
If you want - as per one of your messages - allowance for not being a native-English
speaker, then you should have earlier taken the hint that your initial comment was
incomplete or could be misleading, from the 2 or 3 native-English speakers who responded
with clarifications.
But go ahead, dig yourself in deeper.