# HP 3456A multimeter ROMS gone bad

S

#### [email protected]

Jan 1, 1970
0
I'm looking for ROM images for an HP 3456A multimeter.
Mine has a bad ROM. [email protected]

By the way, if you have this meter I advise that you
back up your roms. The old Mostek ROMS have been
known to go sour after 20 or so years. Same goes

If I can't get lucky here, then I have to blow $100 on another meter on eBay so I can dupe the roms. Sorry about the crosspost, but you folks are most likely to own a 3456A and to have this info. W #### Winfield Hill Jan 1, 1970 0 [email protected] wrote... I'm looking for ROM images for an HP 3456A multimeter. Mine has a bad ROM. [email protected] By the way, if you have this meter I advise that you back up your roms. The old Mostek ROMS have been known to go sour after 20 or so years. Same goes for the Genrad Digibridges etc. If I can't get lucky here, then I have to blow$100 on
another meter on eBay so I can dupe the roms.

Sorry about the crosspost, but you folks are most likely
to own a 3456A and to have this info.

I have two. What kind of PROM did they use? What kind
of modern EPROM / EEPROM would be used in replacement?

I wonder if the ROM program changed over time, and can
be backfitted. Also, other than opening up the insrument
and looking at IC date codes, how can one tell when it
was made, how old it is? Any way to tell from the s/n?

K

#### Kryten

Jan 1, 1970
0
I'm looking for ROM images for an HP 3456A multimeter.
Mine has a bad ROM. [email protected]

By the way, if you have this meter I advise that you
back up your ROMs. The old Mostek ROMs have been
known to go sour after 20 or so years.

EPROM chips typically guarantee 10 years operation,
and chip makers usually halve measured maxima to get a value for data
sheets.
E.g. if they run at 8 MHz, guarantee them to 4 MHz,
if they lose charge in 20 years, guarantee to 10 years.

I'd say top up your EPROMs every <10 years, to be safe.

W

#### Winfield Hill

Jan 1, 1970
0
Kryten wrote...
EPROM chips typically guarantee 10 years operation,
and chip makers usually halve measured maxima to get a
value for data sheets.
E.g. if they run at 8 MHz, guarantee them to 4 MHz,
if they lose charge in 20 years, guarantee to 10 years.

I'd say top up your EPROMs every <10 years, to be safe.

Top-up is a nice phrase... Read the EPROM, erase it,
and re-write it.

J

#### JeffM

Jan 1, 1970
0
steevjanpan @ hotmail.com

cross-post: n. a post where more than 1 group is listed on the Subject
line.
When the topic is applicable to each of the groups,
the practice is acceptable.

multi-post: n. a condition where the same message
is posted individually to several groups.
(1 group is listed on the Subject line of each post.)
The practice is considered to be bad netiquette.

Readers of 1 group who do not read all of the groups
do not gain from the wisdom of those in the other groups.
In addition, it is less likely that mistakes will be corrected.
It is also a bad practice
because people in 1 group will continue to respond

J

Jan 1, 1970
0
D

#### [email protected]

Jan 1, 1970
0
Winfield said:
Kryten wrote...

Top-up is a nice phrase... Read the EPROM, erase it,
and re-write it.

Or even "Read, then re-write," without the erase. The uncharged
bits will stay uncharged, and charged bits will be restored, yes?

If the failure is recent, one might still recover the original
data from EPROMs and ROMs by reading them at lower-than-spec
Vcc, thus reducing their sense-amps' thresholds. (The opposite
technique -- increasing Vcc -- was used in programming many of

Cheers,
James Arthur

S

#### [email protected]

Jan 1, 1970
0
On 20 Apr 2005 03:56:27 -0700, Winfield Hill

What kind of PROM did they use? What kind
of modern EPROM / EEPROM would be used in replacement?

Meters with serial numbers HIGHER-THAN 2015A03070
contain a NEW revision of the ROMS with part number:
U5=1818-1629 U7=1818-1630 U8=1818-1631

The meter contains three 8Kx8 ROMS. These ROMS can
be read on an EPROM programmer as an MC68766, as
long as the programer strobes CS or OE when reading

They can be directly replaced with pin-compatible EPROM
MC68766 or MCM68766C35 but these too are obsolete.

EPROM 27HC641 can be used and is pin compatible, as
long as you cook the data before burning, because A10
and A12 (if I remember correctly) is swapped.

EPROM 2732 can be used if you split the data and solder
in the extra sockets and make some jumper changes etc.

EPROM 2764 can be used but a socket adapter needs to

EPROM 27256 can be used but the data needs to be cooked

....Stepan

S

#### [email protected]

Jan 1, 1970
0
multi-post: n. a condition where the same message
is posted individually to several groups.
(1 group is listed on the Subject line of each post.)
The practice is considered to be bad netiquette.

Readers of 1 group who do not read all of the groups
do not gain from the wisdom of those in the other groups.
In addition, it is less likely that mistakes will be corrected.
It is also a bad practice
because people in 1 group will continue to respond

Thanks for the usefull insight! Very good to know.

Stepan

S

#### [email protected]

Jan 1, 1970
0
By the way, the newer ROMS I listed below CAN be backfitted onto
older instruments.

Stepan

W

#### Winfield Hill

Jan 1, 1970
0
Stepan [email protected] wrote...
By the way, the newer ROMS I listed below CAN be backfitted
onto older instruments.

The NEW revision of the ROM can be backfitted? What's it do?

S

#### [email protected]

Jan 1, 1970
0
The NEW revision of the ROM can be backfitted? What's it do?

I suspect it's just bug fixes. Would you like a copy of the service
manual? over 300 pages and about 81 Megabytes. Painstakingly scanned
in, and with full page 11x17 schematics at 600DPI.

Stepan

W

#### Winfield Hill

Jan 1, 1970
0
[email protected] wrote...
I suspect it's just bug fixes. Would you like a copy of the service
manual? over 300 pages and about 81 Megabytes. Painstakingly scanned
in, and with full page 11x17 schematics at 600DPI.

Would I, he asks, falling all over himself, picking himself up
from the ground, mouth drooling and steam rising from his nose!
Shall I send you a blank CDR in an sase? Or provide an ftp link?

W

#### Winfield Hill

Jan 1, 1970
0
Winfield Hill wrote...
[email protected] wrote...

Would I, he asks, falling all over himself, picking himself up
from the ground, mouth drooling and steam rising from his nose!
Shall I send you a blank CDR in an sase? Or provide an ftp link?

In return, I'll offer a color scan of the elegant color version of
the operator's manual, plus images of the ROM from my newest 3456A.

K

#### Kryten

Jan 1, 1970
0
I suspect it's just bug fixes.
Would you like a copy of the service manual?
Over 300 pages and about 81 Megabytes.

Crikey, just what kind of multimeter is it?!

Is that 81 Megs because you scanned it 600 dpi 24-bit colour and lossless
image files?

K.

S

Jan 1, 1970
0
S

#### [email protected]

Jan 1, 1970
0
Is that 81 Megs because you scanned it 600 dpi 24-bit colour and lossless
image files?

No, no. none of that nonsense. Just plain old 600DPI single bit
bitmap, compressed to PNG. That preserves the halftones in full glory.
The original manual is not in color.

Stepan

K

#### Kryten

Jan 1, 1970
0
No, no. none of that nonsense. Just plain old 600DPI single bit
bitmap, compressed to PNG. That preserves the halftones in full glory.
The original manual is not in colour.

So it is grey scale 8-bit lossless compression, I see.

I do a fair bit of work turning scans of old documents into shiny new HTML.

800 pages is a _bit_ too much, but I tend to store the text in black and
white, which is about 8 times smaller than greyscale and the OCR software
handles. I snip out figures and circuits and store those in the form
appropriate.

I found a company that makes scanners for books: it turns pages so you just
set it going.
Very expensive, but cheaper than hiring people to scan them and is generally
only used for rare or outstanding books.

I wonder if there are companies that will scan books for you with such
machines, and how much they'd charge if I sent them my bookshelves?

S

#### [email protected]

Jan 1, 1970
0
So it is grey scale 8-bit lossless compression, I see.
It's actually 1-bit grayscale. At 600DPI the halftones look great
because the dot pitch of the halftones is less,so it is nicely sampled
without too much aliasing. I'm guessing that compressing a 1-bit image
into an 8-bit format works because it likely affects the dictionary
and not the data aka pointers.

As far as scanning books, I suppose one could forgo the cost of an
expensive scanner by just cutting the binding off a book and then
useing a flatbed with a document feeder.

Stepan

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