Mark Sims | 22 Aug 06:42 2014

HP3458A CAL ram data dumper program

The program outputs a 2kB (or 2 x 32kB) binary ROM image files files along with a couple of ASCII format files
of the data.  2kb for CAL ram and 32kb for DATA ram (probably not needed,  but it can dump the data RAM chips). 
The binary files have the extension .hi and .lo  (CAL ram data is only in the high byte of the memory space). 		
Mark Sims | 22 Aug 03:33 2014

HP3458A CAL ram data dumper program

I have the GPIBKIT version of my HP3458A cal ram data dumper program available.  If you want to try a copy shoot
me an email.   If  it works out, I'll see if John wants to include it in the standard toolkit distribution.
You will need to download GPIB tool kit from the KE5FX.COM web site,  run the tool kit configuration program
(PROLOGIX.EXE)  to setup it up for your interface (it works with Prologix and NI compatible interfaces), 
copy my HP3458.EXE program to the GPIBKIT directory and run it.  Check the comments at the start of
HP3458.CPP for some info.  Run HP3458.EXE without any command line arguments for program usage help. 		 	  
Mark Sims | 21 Aug 18:46 2014

HP 3458A Mem test 1 hight. How do you read 32K memory chips?

The first bit of code I wrote was for DOS/WIN98.  It was kludged into an old serial port monitoring program
that I wrote in like 1985... using Microsoft QuickC.
I am now working on a version that uses John Miles GPIBKIT library.  It is on an NT system...  the code is also in C
(Microsoft Visual Studio (?) compiler,  although with .CPP file name extension).  It should be compatible
with WIN98 and later.  That code seems to be woking fine with my Prologix emulator, but is having some issues
with the NI GPIB-232CV box. 		 	   		  
Mark Sims | 21 Aug 08:52 2014

HP 3458A Mem test 1 hight. How do you read 32K memory chips?

I'm porting over my HP3458A NVRAM data dumper program to use John Miles GPIBKIT routines.  It should make it
usable with most GPIB interfaces out there and be able to run under more modern versions of Windoze.   
My first crack at it is working,  but it is quite a bit slower than my original program.  Not sure if anything can
be done about that...  BTW, my program does verify the checksum bytes in the CAL ram so there is a check that
the dump went OK.  Without Poul-Henning's work none of this would be possible. 		 	   		  
Mark Sims | 21 Aug 04:30 2014

HP 3458A Mem test 1 hight. How do you read 32K memory chips?

Why risk having to re-cal the meter?  There are several GPIB-232CV's on Ebay right now...  Two of them  are
under $60 Buy-It-Now...  cheap enough to be worth trying.  The Prologix USB converter is around $100...
$150 new from the factory. 		 	   		  
Mark Sims | 21 Aug 04:20 2014

HP 3458A Mem test 1 hight. How do you read 32K memory chips?

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.   		 	   		  
Mark Sims | 21 Aug 02:33 2014

HP 3458A Mem test 1 hight. How do you read 32K memory chips?

You REALLY don't want to mess with that 24 pin NVRAM chip... it contains the calibration memory.  If you
bugger the data in it,  you get to spend a couple of grand getting the meter back into working order.  I know a
couple of people that did just that.

The solution is to first make a backup copy of the memory contents using the (undocumented) MREAD command
over the GPIB bus.  Poul-Henning Kamp figured out how to do it... buy the man a beer... even better a case of
beer...   Search the archives for details.  

I just backed up all the memory in my 3 HP3458A's for when the inevitable BIG BAD DAY comes and the backup
batteries go bye-bye.   If you happen to have a NI GPIB-232CV-A (or possibly a Prologix) RS-232 to GPIB
converter and can run a DOS or WIN98 program,  I have a program that dumps the memory chips.  It has code for the
Prologix in it,  but I've only used it with my a Prologix compatible unit I built... I don't have a real
Prologix to test it with.

John Phillips | 20 Aug 22:53 2014

HP 3458A Mem test 1 hight. How do you read 32K memory chips?

I have removed my 32k memory chips form my 3458A. Doe anyone have an easy
way to connect them to a windows computer. USB would be my preferred
connection to a 28 and 24  pin socket. I would like to be able to read and
write to the chips to validate the data.
I have replace the chips and still get Mem test 1 High on start up.
​I really do not want to spend close to $3000 for KeySight to fix this.​



*John Phillips*
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Mark Sims | 20 Aug 06:16 2014

A cute doohicky

I recently bought a couple of these gizmos:  ($19 bucks a pop)

Stick in a semiconductor/r/l/c/etc,  press the button,  and it tells you what it is,  the pinouts,  and
relevant parameters.  Works amazingly well.  

They are based on an open-siource design discussed here.$20-lcr-esr-transistor-checker-project/

It is well worth reading the documentation:

A very good example of what some VERY simple circuitry and VERY clever coding can do.  The firmware is being
constantly upgraded.  The units with the cruder character mode LCD are lot more amenable to firmware
upgrades than the graphics mode LCD ones that I bought.  		 	   		  
Charles Steinmetz | 20 Aug 04:46 2014

Re: Low Thermal EMF Test Lead Stuff

Stan wrote:

>Discussion of proper lash ups of cal. instruments to home built 
>devices, or even work prototypes, would be very welcome by me. I 
>have read Analog Devices AN-347, but a tutorial with problems that 
>the student must complete the lash ups for, would give me a better 
>idea if I've grasped the subject matter. There are two text books 
>mentioned at the end of AN-347, one by Morrison, the other by Ott. 
>Any suggestion as to which to buy?

Todd suggested Fluke's "Calibration: Philosophy in 
Practice."  Unfortunately, the first edition (the one available free 
on-line) has very little on grounding, shielding, and guarding (only 
3 or 4 pages).  The second edition (pricey, and I don't know of a 
free source) has a much more in depth treatment.  Ch.33 (15pp) is 
devoted to grounding, shielding, and guarding, and you'd want to read 
Ch.33 (14pp, "parasitics") and some other subsections, as well.

I think the Fluke second edition is probably the best available 
practical guide to grounding, shielding, and guarding, so that is 
where I'd suggest you go next, based on what you said above about 
your needs.  I'd buy it in preference to either Morrison or Ott if 
what you are most interested in is a practical guide that explains 
what to do and why.  I have a manual from an HP seminar on the 
subject that is excellent, but I haven't seen it available on-line.

After the Fluke book, if you are still looking for materials, I think 
you'd probably find Morrison's treatment more geared to your needs 
than Ott's (which is not to say it is a "better" book overall).

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Stan Katz | 19 Aug 08:07 2014

What's All This Low Thermal EMF Test Lead Stuff?

I'm a self described volt-nut-near-beer. I don't own a 732A/B, or an
HP3458. I do own HP3456 DMMs that are at the top of my instrumentation
pecking order.  I have all the necessary gear to calibrate these DMMs
according to ancient HP documentation. At the top of my cal. chain is the
731B, called out in HP3456 original documentation.  This hierarchy places
me in the near-beer, or junior member status of the group. I look forward
to being educated, and/or corrected on my understanding of the use of test
leads with precision instrumentation.

 I don't find much ancient HP documentation on test leads. The only
recommendations in the era of the 3456 back to the 1960's is to use as
thick a solid lead of pure copper wire as you can find, and insert the wire
into the drill hole on the banana terminal. If the copper is pure, and has
been properly cleaned, the thermal emf's on both identical length leads
should all be balanced, and cancel out. In any case, pure copper-copper
connections generate the lowest thermal emf. I  will agree that manhandling
16 gauge solid wire can be very inconvenient.

 The path I have taken recently is to order Nakamichi gold over copper
stereo banana plugs for my connections ( I deal in low voltage work
exclusively), as well as gold plated spade lugs to go under the banana
screw-downs. ( My budget ruled out gold over beryllium copper Pomona brand
spades. )  I will then experiment between the two connector types. As for
connections, it seems to me the best course is just to screw down the
banana plugs, or in the case of the spades, just crimp. I'll wing it on the
crimping, and see if simple tools can perform adequately. I would avoid
solder, since how can one form identical topological spots of solder on
every connection, deposited at the exact same place on each connection, and
ensure the exact same weight of solder, to the microgram, on each
connection. Since my modus operandi is to aim for balanced emfs, I think
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