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  1. HP8924-Family-Spectrum-Analyzers
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Epson card upgrade?

 

Looks like my 32k could be upgraded?

P5140023.JPG
P5140023a.jpg

 

Aren't those pictures of the RAM card that goes in the HP-48 calculator?



On Thursday, June 17, 2021, 09:17:36 PM EDT, jb via groups.io <ssnova64@...> wrote:

Looks like my 32k could be upgraded?
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Edited

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I see now.? The HP-48 notes are just the backdrop for the opened Epson.
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On Thursday, June 17, 2021, 10:53:44 PM EDT, Hank Riley via groups.io <n1ltv@...> wrote:
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Aren't those pictures of the RAM card that goes in the HP-48 calculator?
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I don't understand the PCB photos, they appear to be masked or cut-off, but yes a lot of memory cards can be expanded by adding additional chips. Link changes may be required for correct addressing.

I've never tried one in a 892x, but as far as I can tell from published information the RAM extension cards used in the 48SX and 48GX have the same connector and pinout as the "Epson" card for the 892x (and some other HP instruments) and should be compatible

Robert G8RPI.
 

I understand the Photos now, you have just lifted the "skin"? of the card and the frame is in place.
You will need to identify the IC's used.

Robert G8RPI
 

I was trying to ring out the lines from the instrument to the card, and compare my 32k card with the 48 project.
This one has a little more to it but not much. Memory is one HY628100b, but the board is pinned out to
accept different options and different jumpers select what to do with lines not used in the 32k.?
The smaller chip is DS1312 for battery backup management. The hp48 projects just use a dual diode to
isolate the battery from external battery from the instrument.? I was looking into this last year and my notes are crap.
This one maybe a newer version and has no shutter.? I have another with shutter that is HP branded rather than
Agilent.? I was going to build one of these but the problem of making gold plate on the edge conn. put it off.
It came apart OK by pulling the battery and 20min in 90% Isopropyl and a single edged razor blade.
Has anyone actually tried a 48sx/gx card in a 8920A?

IMG_0003.jpg
notes.jpg

 

The edge connector is the same as a PCI card. I did some trials years ago using a PCI riser cable intended for low profile rack mount PD case.

Robert G8RPI.
 
Edited

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This is a goal near and dear to my heart.? I think as a group we ought to be able to crack this and maybe get PCBs made for both the Epson and the standard SRAM formats.? Last week I ordered some double row female sockets just like the regular SRAM cards use.? The prices for these cards are just too much seeing as how CMOS ram is dirt cheap now.
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Was wondering what the heck the little package was.? A relief that it's nice but really optional.
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Don't you think having the edge pads tinned as done by the Chinese PCB houses would be good enough for non-commercial purposes?? I think so.
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By the way, my idea is that to relieve the strain of designing the parts into a very thin package, to instead make a PCB that would hang out a ways and have the parts located there (at least at first).? A 3D printed case would make it reasonably mechanically sound.??
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Just bear in mind that just getting something running is okay as a first step even if it's a little ugly.
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Hank
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On Friday, June 18, 2021, 02:38:09 PM EDT, jb? wrote:
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?I was going to build one of these but the problem of making gold plate on the edge conn. put it off.

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Hank-? Others have complained that tin plate goes flaky.?

I found where someone was trying to use nonvolatile serial ram with a bunch of support/glue/translation chips in an effort to do away with the battery problem?
with voting machines.? Scary hairy and stuck out in the way, but it was a proof of a concept.? They had a high rate of dead batteries and lost votes.

There are 4 more Address lines not used on this board - we need to use compatible ram.? It is CMOS.? I would rather upgrade a card that fits my instrument.
There are errors on my notes, pads for SOP vs TSOP others.? Doing some more ringing out and will share.?

Still wondering if ANYONE has verified the simpler 48gx cards actually work??????
 

Reading some comments on the net regarding homemade HP48 cards, it seems that tinned fingers are degraded by being in direct?contact with gold sockets.

Tin and lead are far from gold in the galvanic series.? In fact, because gold is at one end of that series, gold bothers everything except more gold.? I would expect that simply not leaving a DIY tin plated card inserted in the HP for long periods will prevent any significant deterioration.? The PCB houses do, though, provide for gold plating; it's just a bit more expensive, but probably a good idea once a design is finalized.

I appreciate that jb is on track to upgrade the capacity of his card rather than make a new complete DIY card, but there will still be strong synergy between doing an upgrade and doing a DIY card.

?jb: Others have complained that tin plate goes flaky.?
 

For progress report on the specific Epson type 32k card 85700A above,
move J5 to J4 and J7 to J6 to enable 2 more Address lines for an instant 128k card.

So far, unknown missing devices on the board may be
needed for an upgrade to 512k chip (or 2).

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