Foothill Flea Market


Did anyone here happen to go to the Foothill Flea Market (Silicon
Valley) this morning (Saturday, August 13, 2005)?

I was out of town, so I couldn't attend, but there was apparently
one fairly uncommon HP calculator there. Unfortunately he didn't
buy it for me, but maybe someone else here got it.


Well, guess it wasn't one of the regulars here.

It was an HP-81, and the asking price was $50. Sigh.


Have you seen a 27 on eBay last month? Yes, an HP-27 not the 27S. Well, it first showed on our local auction. Half an hour to end, it was less than $40. It was midnight and I was not smart enough to wait till the last minute to bid. I thought the other bidder was sleeping, she was not. In short, I quit when the price went over $100. A week later it was on eBay: sold for $395 or so...

I have no special interest on the HP-27 (I would prefer an easier to find 34C) but it's one of the Woodstocks still unsupported by Nonpareil. If I'd gotten it for a low price, I would have sent it to you... Maybe in four or five years when one of these shows up again...



Edited: 15 Aug 2005, 10:24 p.m.


I have no special interest on the HP-27 (I would prefer an easier to find 34C) but it's one of the Woodstocks still unsupported by Nonpareil. If I'd gotten it for a low price, I would have sent it to you... Maybe in four or five years when one of these shows up again...

Thanks for your support of Nonpareil! As it happens, I now have ROM dumps from the 27 and 29C, and they will most likely be in the next release of Nonpareil. I have a few minor bugs to track down yet, and I need to put together suitable image and KML files.

I also have dumps from the 19C and 67, but they will require more work and won't be supported in Nonpareil as quickly.

The pre-1983 models that I still require in order to get ROM dumps are:

  • 10C
  • 81
  • 92 (mine doesn't work; I might still be able to dump its ROM)
  • 9100A, 9100B
  • 9805
  • 9821
  • 9830
  • 9831
  • 9835A, 9835B
  • 9845A, 9845C

Because they have different ROM revisions, it might be useful to dump ROMs from these models as well:

  • early 19C
  • early 29C
  • early 67
  • late 80 with two quad ROMs instead of seven-ROM hybrid
  • early 97

In addition, I would like to find NON-WORKING units of the following models for destructive ROM dumping:

  • 01 (watch)
  • 10 (handheld printing four-function)
I have working units of those models but am unwilling to sacrifice them. An 01 *might* still be functional after I'm done with it, but it would have reduced long-term reliability, so I'd much rather start with one that is already broken.

For all pre-1983 models other than the 01 and 10, the ROMs can be dumped electrically with no harm to the calculator.

Best regards,



I see that the 95C is absent from your wish list. Do you think David would risk this living piece of history in order for you to extract the ROM?

Mark Hardman

Houston, TX

Edited: 17 Aug 2005, 10:32 p.m.


I think I've got the 95C covered. I know where three working units are (including David's), and I'm pretty sure I can get at least one of the owners to let me dump the ROMs. One of them has said that once I can demonstrate dumping the 97 ROMs without damage (since it has very similar hardware aside from the card reader), that he'll let me do it.
I haven't yet reached that milestone.


As for the risk of "damage" when dumping HP ROMs, early this year it was necessary to desolder each and every of the ROMs. Then, if the ROMs got damaged by overheat, then the contents was lost, and so was the calc.

Since then, the reader hardware and software has improved and it's only necessary to desolder the CTC (on Classics) or the ACT (on Woodstocks) and after ROM reading, put them back.

If something evil happens to the CTC/ACT chips, they can easily be replaced by similar chips from other calcs.

BTW, from the many ROM chips I have desoldered and read out, *** NONE *** was damaged. But the new method that just puts the CTC / ACT chips on risk is the preferred one, especially for the rarer calcs such as the HP27 or HP70.



On the Spice and Voyager series, no desoldering is necessary.

On Topcat series, there is often a jumper in the ISA signal which was intended specifically to be removed for automated test, so only that jumper needs to be desoldered and resoldered.

However, I have an as yet untested idea as to how to dump ROMs from Classic/Woodstock/Topcat models without desoldering anything.

I'm not trying to convince anyone to subject their HPs to anything risky, nor would I ever do anything to someone's HP without fully explaining it first. And I'm not going to do anything that I wouldn't do to one of my own prized calculators.


Eric, will you be at hhc2005? Can you pull the roms from a 10c if I have one there on Saturday?


I expect to be at the conference, but that's not yet certain. I could bring the hardware necessary to dump the ROM contents. It's just a fairly small device that attaches to a USB port on my laptop, and has six HP logic analyzer test clips that attach to pins of the ICs. (Technically only four clips are necessary, for one clock phase, SYNC, ISA, and ground, but I usually wire up the other clock phase and the data line as well. The data line provides an additional check of the integrity of the dump.)

Have you already examined the innards of your 10C? Do you know whether it is of the original construction with the LCD and electronics module separate from the keyboard PCB, or the later single-PCB design? I've seen the innards of two 10Cs of the earlier design. Those are much harder to work with, which is why I'm hoping to find one of the later construction style. But I'm not actually certain whether HP made any 10Cs that way.



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