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

[J. L. Trantham]

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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