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Dr. Frank Stellmach

Thu, Aug 26, 2010 7:54 PM

" So I would recommend you make a backup of the CALRAM with the MREAD

command (I described how to in a post some time back) and let your
batteries run out.

If like me, you keep the meter powered, it may never happen.

Poul-Henning"

Poul-Henning,

as far as I remember your recent post, you were not able to read all memory locations by MREAD,
but instead desoldered the NVRAMs and transferred their content by an EPROM Programmer?!

Or did you find a way in the meantime to fully extract the content by MREAD?

I fear to desolder the NVRAMs on my 3458A and destroy the content, before I could read it on a programmer.

Frank

" So I would recommend you make a backup of the CALRAM with the MREAD command (I described how to in a post some time back) and let your batteries run out. If like me, you keep the meter powered, it may never happen. Poul-Henning" Poul-Henning, as far as I remember your recent post, you were not able to read all memory locations by MREAD, but instead desoldered the NVRAMs and transferred their content by an EPROM Programmer?! Or did you find a way in the meantime to fully extract the content by MREAD? I fear to desolder the NVRAMs on my 3458A and destroy the content, before I could read it on a programmer. Frank

O

Oz-in-DFW

Thu, Aug 26, 2010 9:23 PM

On 8/26/2010 2:54 PM, Dr. Frank Stellmach wrote:

" So I would recommend you make a backup of the CALRAM with the MREAD

command (I described how to in a post some time back) and let your
batteries run out.

If like me, you keep the meter powered, it may never happen.

The batteries them selves have a self discharge mechanism. Most are far
better than their rated leakge, but still have finite leakage and will
eventually die. They will also eventually fail, and some fixed
percentage will fail short. I've replaced a number of the Dallas parts
who's batteries failed short.

Back it up.

--
mailto:oz@ozindfw.net
Oz
POB 93167
Southlake, TX 76092 (Near DFW Airport)

On 8/26/2010 2:54 PM, Dr. Frank Stellmach wrote: > " So I would recommend you make a backup of the CALRAM with the MREAD > > command (I described how to in a post some time back) and let your > batteries run out. > > If like me, you keep the meter powered, it may never happen. The batteries them selves have a self discharge mechanism. Most are far better than their rated leakge, but still have finite leakage and will eventually die. They will also eventually fail, and some fixed percentage will fail short. I've replaced a number of the Dallas parts who's batteries failed short. Back it up. -- mailto:oz@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport)

PK

Poul-Henning Kamp

Thu, Aug 26, 2010 9:26 PM

In message 4C76C67B.3010101@freenet.de, "Dr. Frank Stellmach" writes:

as far as I remember your recent post, you were not able to read
all memory locations by MREAD,

You can read any memory location, but you cannot write the CALRAM
(with the MWRITE command) because it is protected by a couple of
layers of protection in hardware.

You can write the CALRAM by downloading a M68K program that does
the right gyrations to open the protection mechanisms. There does
not seem to be any published data on this however, I had to disassemble
the code in the ROMS to find out how that worked.

But if you read a copy with MREAD and save that, you can always
program a new CALRAM chip in a EPROM-programmer or by other means.

Poul-Henning

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

In message <4C76C67B.3010101@freenet.de>, "Dr. Frank Stellmach" writes: >as far as I remember your recent post, you were not able to read >all memory locations by MREAD, You can read any memory location, but you cannot write the CALRAM (with the MWRITE command) because it is protected by a couple of layers of protection in hardware. You can write the CALRAM by downloading a M68K program that does the right gyrations to open the protection mechanisms. There does not seem to be any published data on this however, I had to disassemble the code in the ROMS to find out how that worked. But if you read a copy with MREAD and save that, you can always program a new CALRAM chip in a EPROM-programmer or by other means. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

PK

Poul-Henning Kamp

Thu, Aug 26, 2010 9:33 PM

In message 4C76DB39.2020708@ozindfw.net, Oz-in-DFW writes:

The batteries them selves have a self discharge mechanism.
[...]

Back it up.

I fully agree, I just wanted to moderate the panic-attacks people
seem to be having over the NVRAM chips.

Make a backup copy, don't sweat it until you have the problem or
the time and energy to tackle the replacement.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

In message <4C76DB39.2020708@ozindfw.net>, Oz-in-DFW writes: >The batteries them selves have a self discharge mechanism. >[...] > >Back it up. I fully agree, I just wanted to moderate the panic-attacks people seem to be having over the NVRAM chips. Make a backup copy, don't sweat it until you have the problem or the time and energy to tackle the replacement. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

volt-nuts@lists.febo.com

MREAD 3458A