HP 3468A owners UNITE: a storm is coming! But together we found the solution!

[iDevice]

Looking back at the pictures I found and referenced in one of my previous post, I was a bit puzzled to see that it was not a Mostek rom.
So your discovery adds another layer of uncertainity.

I didn't have time yet to open mine, but I wouldnt be too surprized if it wasn't a Mostek either...

So the plague could not be as widespread as we may have though in the first place.

[Kjelt]

So the plague could not be as widespread as we may have though in the first place.

That would be good news, also if the rest of the hardware is the same (latching etc.) so we can substitute the Mostek with a normal 27C64.

[Sailor]

Yes, that part number is (or was) the replacement part number for the Mostek device (1818-1753). I don't know who the manufacturer is, but maybe HP got wind of the problem very early, and changed.

Edit: Maybe it's Signetics - I was initially looking at it as SKK

[Deathwish]

@All_repair . Can you put a text file in that zip file to say what the contents are and from please. it gets harder 6 months later when you have a shed load of rom files but no idea what they are from.

[amyk]

So the plague could not be as widespread as we may have though in the first place.

That would be good news, also if the rest of the hardware is the same (latching etc.) so we can substitute the Mostek with a normal 27C64.

The latched version of the 27C64 is the 87C64, and you can still get 87C64s.

[Deathwish]

I think all_repair has solved it for you all. a search on the number he provided as a part number 03468-65501  throws this up

http://bbs.38hot.net/thread-7294-1-1.html

Translated to english it says this

Posted on 2011-3-4 05:18:19 | This Author
I have ROM program.
 HP3468A-ROM (03468-65501-DC-8817) .rar (7 KB, downloads: 82)

I have attached The rom from that site to this.

also there is this
http://hl2kvx.tistory.com/4421

[ivan747]

Now we only need somebody who reads chinese? I'm gonna try registering to reupload that here.
Registering is proving difficult for me.

[Deathwish]

Already done my friend, I just uploaded it and edited my post prior to this one.

[ivan747]

Haha, you gotta look at the registration email... I understand absolutely nothing 

Thanks for that

[Kjelt]

I think all_repair has solved it for you all. a search on the number he provided as a part number 03468-65501  throws this up
ROM program  HP3468A-ROM
I have attached The rom from that site to this.

That would be great, I have done a short comparison to Sailors binary, unfortunately his binary data is in some sort of s19 format and can't be directly compared to the rom you posted, however on first sight there are a lot of similarities and also a lot of differences. The differences are mainly bits that went from 0 to 1, this is just a very short first glance and comparison of a few strings in the first 4k. Perhaps Sailor can provide a comparable binary formatted file so we can do a 1 on 1 comparison.
It looks promising 

[Deathwish]

Think I fell in love with that Chinese site ... Just got a shed load of UNI-T schematics for the DMM range....

[MarkL]

...
 I have done a short comparison to Sailors binary, unfortunately his binary data is in some sort of s19 format and can't be directly compared to the rom you posted, however on first sight there are a lot of similarities and also a lot of differences.
...

If you have a linux box, there's a utility called "srecord" which can read and write many different kinds of EPROM file formats.  It can convert to binary so you can do a direct comparison.

Maybe available for windows too, dunno.

[dom0]

I think all_repair has solved it for you all. a search on the number he provided as a part number 03468-65501  throws this up
ROM program  HP3468A-ROM
I have attached The rom from that site to this.

That would be great, I have done a short comparison to Sailors binary, unfortunately his binary data is in some sort of s19 format and can't be directly compared to the rom you posted, however on first sight there are a lot of similarities and also a lot of differences. The differences are mainly bits that went from 0 to 1, this is just a very short first glance and comparison of a few strings in the first 4k. Perhaps Sailor can provide a comparable binary formatted file so we can do a 1 on 1 comparison.
It looks promising 

srecord is be able to convert it. Or upload it here and let someone else do it for you

[all_repair]

I think all_repair has solved it for you all. a search on the number he provided as a part number 03468-65501  throws this up
ROM program  HP3468A-ROM
I have attached The rom from that site to this.

That would be great, I have done a short comparison to Sailors binary, unfortunately his binary data is in some sort of s19 format and can't be directly compared to the rom you posted, however on first sight there are a lot of similarities and also a lot of differences. The differences are mainly bits that went from 0 to 1, this is just a very short first glance and comparison of a few strings in the first 4k. Perhaps Sailor can provide a comparable binary formatted file so we can do a 1 on 1 comparison.
It looks promising 

I have both bin and intel hex format of my rom in my attachment.  You may see if it has the same format aa sailor.  I can't verify the chinese site rom and my captured bin now.  Anyone can verify?

[dom0]

They are bit-for-bit identical. Looks good.

% sha1sum U502_NS27C64.BIN HP3468A-ROM\(03468-65501-DC-8817\).BIN
1d670ee57e72a318a93e7a70037c89e17755d3ff  U502_NS27C64.BIN
1d670ee57e72a318a93e7a70037c89e17755d3ff  HP3468A-ROM(03468-65501-DC-8817).BIN

[MarkL]

Here's the explanation for the two different pin count ROMs being used in the 3468A.

If you look in the more recent service manual, 03468-90008 (Sept88):

  http://literature.cdn.keysight.com/litweb/pdf/03468-90008.pdf

It shows in the parts list a change to the ROM 03468-65501 (the 28-pin one) for a specific revision of the motherboard.  Snippet below.

What may be of further interest, is that in schematic 7-G-12, it shows the 28-pin ROM *without* any additional latching.  And from all_repair, this is a 27C64.


I think what's still not known is if there's any hardware changes associated with the 28-pin motherboard that would not allow that image to run in the older 24-pin motherboard.

In other words, do we still need a the 24-pin ROM image (1818-1753 or 1818-3123)?

[Kjelt]

I am going to give it a try, don't know if I have enough time to get so far but will try a building a small converter pcb and a 27C64 in the actual device.
Now the question is does it matter if I connect the original /CE of the MK36000 to the 27C64 /CE or /OE they both have the same function as far as I can tell in a short glance on the datasheet?

[Kjelt]

I have both bin and intel hex format of my rom in my attachment.  You may see if it has the same format aa sailor.  I can't verify the chinese site rom and my captured bin now.  Anyone can verify?

Ah thanks it was a hex file Sailor made. So here is comparison screenshot and I attach the file. It looks like there is a lot of similarity (black) and a lot of damaged pieces (red). Now the question is if all the reds are 0's gone to 1's that would make sense, the other way round would make no sense unless it is a different program. 

[all_repair]

I am going to give it a try, don't know if I have enough time to get so far but will try a building a small converter pcb and a 27C64 in the actual device.
Now the question is does it matter if I connect the original /CE of the MK36000 to the 27C64 /CE or /OE they both have the same function as far as I can tell in a short glance on the datasheet?

I think *CE of 27C64 should be grounded, and *OE to *E of MK36000 signal.

[Kjelt]

Just looked more on the comparison and the upper4k from Sailor is almost identical will attach also. The lower 4k is very different also with a lot of 1s going to 0s which is not what I expected.

[Deathwish]

Learning Chinglish is fun, no wonder the Chinese hate the Japanese .... its something to do with a jap oscilloscope.

Japanese did not die, which addresses the boss sent over

Oh well.

[iDevice]

Ok, I had time to open mine a few minutes ago and... damned, I have the Mostek version.
Strange enough, my serial indicates a 1982 model but most chips inside have a 84 date code.

So that means I have a new time-bomb I didn't know about in the lab.
I thought I got rid of all those DALLAS NVRAM and Mostek plague already, but no, so time for unsolder gun again...

Now, I checked the clearance between the top of the chip and the power switch rod and it is about 2mm on mine, so no way to put a socket and certainly not an adapter.
So it's either a sidecar or a Moto EPROM, but none of my programmers supports the old Moto chip and the minipro doesn't support the 25V prog voltage anyway, so even if some are still available on ebay, I'm stuck regarding this option...
Unless someone is able to program them ?

[MarkL]

After looking at the 03468-90008 service manual a bit, I noticed there's no new signature analysis numbers listed for the 28-pin ROM 03468-65501, even though that's the default ROM listed in the parts list.

The signature numbers listed, and the pinout, are for the 24-pin ROM, 1818-3123.

Unless someone forgot to update the signature numbers, it could mean 1818-3123 and 03468-65501 have the same binary image.  I also can't see any differences in the schematics between the two motherboards (24-pin vs 28-pin).

Not conclusive, but just sayin' it looks promising.


The older 24-pin ROM, 1818-1753, has a completely different set of signature numbers.  So if Sailor has that ROM, it's not going to match images from either 1818-3123 or 03468-65501.

I am going to give it a try, don't know if I have enough time to get so far but will try a building a small converter pcb and a 27C64 in the actual device.
Now the question is does it matter if I connect the original /CE of the MK36000 to the 27C64 /CE or /OE they both have the same function as far as I can tell in a short glance on the datasheet?

I think *CE of 27C64 should be grounded, and *OE to *E of MK36000 signal.

The schematic for the 28-pin ROM motherboard has /CE and /OE connected together which then goes to /PSEN (would be the MK36000 /CE, pin 20).


EDIT: Clarification: No differences in the motherboards *besides* the 24-pin vs. 28-pin.

[Deathwish]

its going to be no help but it did say this on the chinese post


Remember ROM model is 27C64, 27C128 substitution I had, feet are compatible, multi-wire grounded out to one address.

could the multi wire grounded to one post be .. the reason.

[iDevice]

My '84 model has the 1818-3123 version.