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5334A part reference

 

What is the replacement for part 1820-3639, IC-8-bit-4K ROM?? I am also seeking option 010, XTAL oscillator for this device.
--
Joe White
KW4YW
 

Joe,

I'm not sure if HP changed this part out at some point. I popped the hood on my 5334A and found a microprocessor with a piggybacked ROM, both of which in place of A1U29, yet the service manual only lists the one part. In mine the Microprocessor is a Mostek MK38P70/02H. The ROM plugged into it is a TMS2532JL-45 (HP PN: 1818-0762). From what I recall this ROM has a fairly unique pinout, TI swapped some pins around, so be cautious when sourcing replacements. There's also the issue of finding a dump of the ROM, to program the replacement.

Regarding the oscillator. This is a little more effort than a drop in replacement, but short of finding a broken 5334A to harvest from, it's a viable approach. Many years ago I made a board to adapt an HP 10811-60111 oscillator to the 5334A. That oscillator was much easier to find at the time. Details of the project are on the

Regards,
Ed
KC2FNA


On Wed, May 14, 2025 at 4:38?PM Joe White via <skinnershorse=[email protected]> wrote:
What is the replacement for part 1820-3639, IC-8-bit-4K ROM?? I am also seeking option 010, XTAL oscillator for this device.
--
Joe White
KW4YW



--
Edward Koloski
 

¿ªÔÆÌåÓý

The microprocessor you have was primarily used as a development part.

The PROM was in most of the Mostek microprocessors for one time mask programming.?
What you have allowed the developer to write the program into a UV erasable EPROM
and test the program until they went to production with one time parts.

Sometimes on low run products, the development style parts were cheaper to use than having
hundreds of one shot parts mask programmed.

Jim

From: [email protected] <[email protected]> on behalf of Ed Koloski via groups.io <ekoloski@...>
Sent: Wednesday, May 14, 2025 5:46 PM
To: [email protected] <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 5334A part reference
?
Joe,

I'm not sure if HP changed this part out at some point. I popped the hood on my 5334A and found a microprocessor with a piggybacked ROM, both of which in place of A1U29, yet the service manual only lists the one part. In mine the Microprocessor is a Mostek MK38P70/02H. The ROM plugged into it is a TMS2532JL-45 (HP PN: 1818-0762). From what I recall this ROM has a fairly unique pinout, TI swapped some pins around, so be cautious when sourcing replacements. There's also the issue of finding a dump of the ROM, to program the replacement.

Regarding the oscillator. This is a little more effort than a drop in replacement, but short of finding a broken 5334A to harvest from, it's a viable approach. Many years ago I made a board to adapt an HP 10811-60111 oscillator to the 5334A. That oscillator was much easier to find at the time. Details of the project are on the

Regards,
Ed
KC2FNA


On Wed, May 14, 2025 at 4:38?PM Joe White via <skinnershorse=[email protected]> wrote:
What is the replacement for part 1820-3639, IC-8-bit-4K ROM?? I am also seeking option 010, XTAL oscillator for this device.
--
Joe White
KW4YW



--
Edward Koloski
 

Jim,

That is a truly fascinating bit of information, and thank you for sharing it. It makes sense that HP would eventually replace the microprocessor and UVPROM with a more cost effective mask ROM, assuming a large enough production quantity. I suspect that may be the case with this counter, given the service manual designating a single part number and the original question that started this thread. Good for HP's bottom line at the time, not so much for repairability years on down the line.

If that's the case then I think there's a unique opportunity here. There's a known microprocessor presumably with a documented instruction set, and a UVPROM that can be read. On the other hand, reading the contents of a mask ROM is possible but not as easily as this. From there, if parts are not available, it's not unreasonable to port the fimrware to a modern replacment to repair an instrument.

That motivates me to extract and archive the contents. I'll have to read the datasheet and possibly wire up an adapter for my EEPROM programmer. If I can safely read the contents of this UVPROM, and the others in my counter, I will do so and make the contents available.
 

?
I remember that in my 5334A, the PROM was stacked on the processor. It was nothing special, just a 27C64. I have the PROM dump, it will take a few days to find the file and upload it - please wait.
?
?
?
 

Ed,
?
I remember I found an Easter egg in the PROM of the 5334A (this is a picture from a few years ago):? you can see the name of the programmer in the ROM. Shalom Kattan, who later founded Carmel instrumens.
?
 

For the option 010 you might look at this item.



Greg
 

Excellent teardown and photos!

The service manual does list A1U19, the Executive microprocessor, as two items; the microprocessor and UVPROM, those have different part numbers. MK38P70/02D and MBM27C64-25. HP seems to have retained that. Yours also has a newer firmware than mine (05334-8003).

There are two additional piggybacked microprocessors in my counter, the Measurement microprocessor U29 and the HPIB processor U17. Both seem to have been swapped out for mask ROMs at some point in the production run. They're both the /02H variant of the Mostek with a TI TMS2532JL-45 on top.?

I'm not sure exactly when my counter was manufactured but it's filled with 1983 date codes on all the ICs.


On Wed, May 14, 2025 at 10:03?PM BI4LBK via <chrispotma=[email protected]> wrote:
?
I remember that in my 5334A, the PROM was stacked on the processor. It was nothing special, just a 27C64. I have the PROM dump, it will take a few days to find the file and upload it - please wait.
?
?
?



--
Edward Koloski
 

I appreciate all the input on the replacement.? Under the circumstances I am going to see if I can avoid replacing this part as I do not have the facilities, or the nerve, to fiddle with EPROMs.? My new concern is replacing A1C19, the Sprague 3900uF cap.? Mine let go yesterday in spectacular fashion, magic smoke, magic goo, you name it.? I have not traced the failure to any other component,. yet, but I still need the cap.
?
Thanks and cheers,
--
Joe White
KW4YW
 

The ROM dump of the HP 5334A has been uploaded:
?
/g/HP-Agilent-Keysight-equipment/files/All%20HP,%20Agilent%20and%20Keysight%20instruments%20in%20folders%20by%20part%20numbers/5000%20to%205999/HP%205334A%20Universal%20Counter

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