[volt-nuts] HP 3458A Mem test 1 hight. How do youread 32K memorychips?

[John Phillips]

I plan on doing a complete cal as well.


On Thu, Aug 21, 2014 at 8:49 AM, Bill Gold <wpgold3637 at att.net> wrote:

> Correct, I didn't read the NVRAMS.  I didn't have a prom reader/writer that
> would handle these devices anyhow and no GPIB interface that worked
> anymore.
> Actually I have two 3458A.  Once I was completely done with the first one
> including the cal I didn't even try to put the original NVRAMS removed from
> the second meter, just put in the new ones and proceeded to the cal
> procedure.
>
> Bill
>
> ----- Original Message -----
> From: "J. L. Trantham" <jltran at att.net>
> To: "'Discussion of precise voltage measurement'" <volt-nuts at febo.com>
> Sent: Thursday, August 21, 2014 7:53 AM
> Subject: Re: [volt-nuts] HP 3458A Mem test 1 hight. How do youread 32K
> memorychips?
>
>
> > Bill,
> >
> > Thanks for the insight.
> >
> > I always thought that I lost my CALRAM data by trying to read the chip in
> my
> > programmer while the chip was still warm.  What you are saying is that
> you
> > did not try to read your chip, just unsoldered, installed a socket,
> plugged
> > it back in and the data was corrupted.
> >
> > Very interesting.
> >
> > I have done this to three 3458A's and only lost the data on one of the
> > units.
> >
> > This further supports the need to be able to read the contents before
> > unsoldering and have that data be able to be used to program a new chip.
> >
> > Thanks for the insight and I would love to try some programs to do that.
> I
> > only have Windows systems but I have several USB to GPIB adapter choices,
> > PCI to HPIB adapter choices, and RS232 to GPIB adapter choices.
> >
> > Joe
> >
> > -----Original Message-----
> > From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
> > Behalf Of Bill Gold
> > Sent: Thursday, August 21, 2014 9:33 AM
> > To: Discussion of precise voltage measurement
> > Subject: Re: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K
> > memorychips?
> >
> > When I removed the original NVRAM devices and then put in sockets, I
> plugged
> > the original devices back in just to see if everything worked.
> Apparently
> > some cal data was lost just desoldering the devices as I got error
> messages.
> > It really didn't concern me as I intended to completely recal the meter
> with
> > my local "standards" anyhow.  It was hours before I plugged the original
> > devices back in so they were completely at room temp.  My guess was that
> > since the date codes were 1992 and I did this in 2010 the batteries were
> > almost dead after 18 years and just the shock of desoldering caused "the
> > end".
> >
> > Bill
> > ----- Original Message -----
> > From: "Mark Sims" <holrum at hotmail.com>
> > To: <volt-nuts at febo.com>
> > Sent: Wednesday, August 20, 2014 7:20 PM
> > Subject: [volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K
> > memorychips?
> >
> >
> > > The problem with removing the chip and copying it is the very real
> chance
> > of glitching the contents in the process.  Much better to make a backup
> copy
> > first.
> > >
> > > The 32Kx8 NVRAMS are used for system memory and things like storage of
> > user programs and data.
> > >
> > > Note that the two 32Kx8 devices are form a 16-bit word.  The 2kx8 cal
> ram
> > is only on the high byte of the data bus.  MREAD returns memory contents
> as
> > a signed integer value (-32768..32767) in ASCII.
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-- 

*John Phillips*