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.

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@hotmail.com> To: <volt-nuts@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. > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

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@febo.com [mailto:volt-nuts-bounces@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@hotmail.com> To: <volt-nuts@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. > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.

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@att.net> To: "'Discussion of precise voltage measurement'" <volt-nuts@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@febo.com [mailto:volt-nuts-bounces@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@hotmail.com> > To: <volt-nuts@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. > > _______________________________________________ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

I plan on doing a complete cal as well. On Thu, Aug 21, 2014 at 8:49 AM, Bill Gold <wpgold3637@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@att.net> > To: "'Discussion of precise voltage measurement'" <volt-nuts@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@febo.com [mailto:volt-nuts-bounces@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@hotmail.com> > > To: <volt-nuts@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. > > > _______________________________________________ > > > volt-nuts mailing list -- volt-nuts@febo.com > > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > > and follow the instructions there. > > > > _______________________________________________ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > > _______________________________________________ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- *John Phillips*