Re: 11801 NVRAM

Sergey Kubushyn

On Tue, 17 Sep 2019, Chuck Harris wrote:


Yes, it might be. Good to have EEPROMs copy anyway. I don't also know what
ROM versions are in my 11801C and it is in my own far storage corner on a
shelf so it would take quite an effort to get there and check. Have too many
stuff and in major remodeling (?) now -- lots of construction work, finally
installing my lathe/mills/breke/sheet metal tools/machinery and so on...
Unfortunately it is not something quick and as a matter of fact can take
forever -- it is impossible to complete, one can only stop that process at
some point :)

I do remember that 11801C has everything CSA803A had and more by default but
not sure if it applied to all of them or starting at some serial number. And
that "Option" noun is that bothers me...

Hi Sergey,

I am getting ready to do some EPROM copying, and was looking for
parts information... which is sadly missing from my manual.

I did run across a little bit on instrument options that states
option 1T is standard after serial B020000, as is my machine, but
still shows up in the identify pop up menu. This option can be
added to pre B020000 instruments.

So, we may be chasing nothing.

-Chuck Harris

Sergey Kubushyn wrote:
On Mon, 16 Sep 2019, Chuck Harris wrote:

Sorry for jumping in but is it somehow possible to share those ROMs?

I do have 11801C sitting on a shelf with difficult access to it and I'm not
sure it has 1T option that would've been nice to have...

My 11801C, with OPTS 1T (Telecom std masks),

has, Exec: 4.05, Disp: 4.00, Timebase/Controller: 4.03, ACQ1: 9.02, ACQ2: 9.02

-Chuck Harris

Reginald Beardsley via Groups.Io wrote:
My scope is an 11801. That should be visible in the screen photo I posted.
Based on the dates on parts it is 1989 production. It is enough different from
the 11801C that it was obvious from the meager information in the service manual
for the 11801C that I needed an actual an 11801 manual. Zenith was kind enough to
furnish a scan of the 11801 service manual, which is now available online, but I
bought a paper copy.

I currently am triggering off a square wave on one channel of the 33622A while
displaying a ramp from the other channel. There is a periodic jitter in the time
base, so even with an external trigger I cannot get a stable sweep. In 1024 point
mode at 1 ps/div it appears that there are 4-5 subsweeps before it repeats. As a
result the trace oscillates back and forth over a span of about 1.3 ps as it
drifts across the screen. In 5120 point mode it seems to have just 2 subsweeps
with ~1 ps dither between them.

When the OXO heater kicks on everything jumps out of sync for a while. It may
well be that the mystery NVRAM calibration constants are intended to correct the
time offset between the sweeps. IIRC my timebase ROMS have a 1991 or 1992 date,
so it is possible that my scope had a FW update and could be corrected if I knew
where and what values to write with a PROM programmer.

If someone has an 11801C or other newer model open I'd appreciate version and date
information on the timebase board ROMS. But if anyone knows *anything* about this
I'm very interested in investigating. I've got another 11801x in CA at my
sister's house which I'm waiting for her to ship to me. I have had more fun with
my 11801 than any other piece of test gear I've bought. Being able to see
reflections from each side of a high grade SMA-F to N-F adapter is quite amazing.

Have Fun!

* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *

* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *

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