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HP Forum Archive 14

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HP42s memory upgrade
Message #1 Posted by Michael on 23 Jan 2005, 4:36 p.m.

Hi all,

I am wanting to try the memory upgrade on one of my hp42s's and am trying to locate 1 or 2 of the 62256 32K, low power, 28-pin, surface-mount RAM IC's.

The trouble is I am having trouble locating this IC. I'm from Melbourne, Australia so I have tried Farnell's, RS Components and a number of smaller outlets, but no luck.

Is anyone out there able to point me in the right direction??

Thanks

Michael

      
Re: HP42s memory upgrade
Message #2 Posted by Vieira, Luiz C. (Brazil) on 23 Jan 2005, 6:20 p.m.,
in response to message #1 by Michael

Hi, Michael;

I upgraded a few HP42S (one is still with me) and I used some different sources: dammaged/broken HP48G, one old sound board (it had three IC's) and even one hard-disk main board. I did not use new components in any of the HP42S I upgraded (about six), and their owners were aware of this fact. At least as far as I know, three of them still work perfectly fine.

Just to let you know about these possible sources.

Best regards and success!

Luiz (Brazil)

Edited: 23 Jan 2005, 6:22 p.m.

            
Re: HP42s memory upgrade
Message #3 Posted by Michael on 23 Jan 2005, 8:13 p.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)

Thanks for the reply, is there any particular brand of sound card because I just looked at an old Sound Blaster card and it had nothing.

Thanks again,

Michael

                  
Re: HP42s memory upgrade
Message #4 Posted by Vieira, Luiz C. (Berazil) on 23 Jan 2005, 9:08 p.m.,
in response to message #3 by Michael

Hello, Michael;

I have the soundboard in my hands right now and I see no particular ID on it. My scanner is disconnected right now, so I can generate an image for you later, if applicable.

There's a paper label on it that reads '96-03-081 4055' and we can see two big PQPF IC's with paper labels as well:

 _______________     ______________
|               |   |              |
|  TOPCAT 1A    |   |  CANINE 1A   |
|  2010         |   |  2067        |
|_______________|   |______________|
The IC's are, in fact, organized in columns instead of rows, as suggests my "drawing".

The PCB (solder side) has the following inscription: TBSMS05.2 The main signal processor is a Motorola DSP56001AF C27 and the three memory chips used in this board are MT62C256F-70LL (I can't identify the brand; it reads 'MOT', but the 'O' in 'MOT' has crossed lines like tic-tac-toe)

The hard disk is a 341 MBytes Seagate ST3991A. The memory chip on it is a Winbond W24257S-70L.

Based on the fact that the calculators did not show a measurable current consumption (bellow .1mA with my standard multimetter), I guess the 'L' in both IC's after the 70 (access time in micro seconds?) reffers to Low power.

Hope this helps.

Cheers.

Luiz (Brazil)

Edited: 23 Jan 2005, 9:14 p.m.

                        
Re: HP42s memory upgrade
Message #5 Posted by Michael on 23 Jan 2005, 9:39 p.m.,
in response to message #4 by Vieira, Luiz C. (Berazil)

Thanks again for the quick response,

Yes, an image would be great when you get time (a picture says a thousand words). I might go over the boards I have looked at because I have been looking for a 28 pin with 62256 on it, I didn't Realize there were so many variables.

Michael

                              
Re: HP42s memory upgrade
Message #6 Posted by Rick on 24 Jan 2005, 5:53 a.m.,
in response to message #5 by Michael

Try CY62256L-70SNC . You can get this here : www.digikey.com

                                    
Re: HP42s memory upgrade
Message #7 Posted by Rick on 24 Jan 2005, 5:55 a.m.,
in response to message #6 by Rick

Actually you may be able to get this in any electronics store in Australia.

                              
Re: HP42s memory upgrade
Message #8 Posted by Nelson M. Sicuro on 24 Jan 2005, 6:55 a.m.,
in response to message #5 by Michael

You can look at the picture I took of my 42S: http://www.hp42s.com/news/doorsopen.html

Best regards,

Nelson

                                    
Re: HP42s memory upgrade
Message #9 Posted by Michael on 24 Jan 2005, 9:51 p.m.,
in response to message #8 by Nelson M. Sicuro

Thank you all for your hints, I will track one down and let you know how I go.

Michael

      
Re: HP42s memory upgrade
Message #10 Posted by Michael on 6 Feb 2005, 4:53 p.m.,
in response to message #1 by Michael

Hi all,

Just like to say thanks for everyone's comments and help and to say I have successfully upgraded the memory in my 42s to 32k. Everything went smoothly, it was easier than I thought it would be, you just have to take your time.

I was also wondering by doing this memory upgrade have I de-valued the 42s at all?

Thanks

Michael

            
Re: HP42s memory upgrade
Message #11 Posted by Vieira, Luiz C. (Brazil) on 7 Feb 2005, 12:13 a.m.,
in response to message #10 by Michael

Hi, Michael;

I thought about this once, when I first upgraded my own. Then I thought: "Who said I want to sale it, now that it has 32KRAM?".

You bet I never thought about that again...

Cheers.

Luiz (Brazil)

(P.S. - I did not answer your question... In fact, I don't know if an upgraded HP42S values less than an original. As a collecting piece, every change reduces the price of the "hacked" unit, agree?)

                  
Re: HP42s memory upgrade
Message #12 Posted by Thomas Okken on 7 Feb 2005, 7:16 a.m.,
in response to message #11 by Vieira, Luiz C. (Brazil)

In fact, I don't know if an upgraded HP42S values less than an original. As a collecting piece, every change reduces the price of the "hacked" unit, agree?

That seems to be true in general, but with the HP-42S in particular, there is the suspicion that its value is currently determined not by collectors, but by people who want one to *use*. (I have heard that the situation with the HP-48GX is similar.)
And from the perspective of someone buying a great tool, as opposed to a collectible that they intend to stick in a display case, I'd have to say a 32k unit may well fetch even more than an unmodified one (if the buyer isn't worried about damage caused during the modification, that is (speaking personally, *I* would worry about that, and that's why *my* 42S will stay at 8k)).

Edited: 7 Feb 2005, 7:31 a.m.

                        
<Why?>HP42s memory upgrade
Message #13 Posted by Marx Pio(Amazon) on 8 Feb 2005, 7:13 p.m.,
in response to message #12 by Thomas Okken

Hi all you HP fans,

Upgrade an HP42S for what reason? Geek fun? We would die before finish to type a 32kbyte program. And if even you have a structural stiffness matrix for inversion I think a PC is more suitable.

A serious upgrade for me is:

1 MB ram minimum SD, MMC or Compact flash slot Support for USB or serial Windows-based SDK for real program typing and debugging More Two or three display lines and all in a HP42 size. Is it possible? :^)

Still dreaming, ZZZZZZzzzz

Pio

                              
Re: <Why?>HP42s memory upgrade
Message #14 Posted by Thomas Okken on 8 Feb 2005, 7:23 p.m.,
in response to message #13 by Marx Pio(Amazon)

Sorry, can't resist...

A serious upgrade for me is:

1 MB ram minimum
SD, MMC or Compact flash slot
Support for USB or serial
Windows-based SDK for real program typing and debugging
More Two or three display lines

and all in a HP42 size. Is it possible? :^)

That's a Palm with Free42 you've just described, Marx. OK, the extra display lines won't be available until later this year, but development on Windows is possible, and will be even easier next week or so when I publish Vini Matangrano's text-to-raw conversion script on the Free42 web site.

If only there were Palms with a decent keyboard... Or any keyboard, for that matter...

- Thomas

Edited: 8 Feb 2005, 7:45 p.m.

                                    
Re: <Why?>HP42s memory upgrade
Message #15 Posted by Cyril R on 9 Feb 2005, 4:13 a.m.,
in response to message #14 by Thomas Okken

Hi, maybe a hp-48gx with 1mb card is what you described

                                          
Re: <Why?>HP42s memory upgrade
Message #16 Posted by Thomas Okken on 9 Feb 2005, 7:55 a.m.,
in response to message #15 by Cyril R

> Hi, maybe a hp-48gx with 1mb card is what you described

Except for the size...

            
Re: HP42s memory upgrade
Message #17 Posted by Valentin Albillo on 7 Feb 2005, 12:32 p.m.,
in response to message #10 by Michael

Hi, Michael:

Michael posted:

"I was also wondering by doing this memory upgrade have I de-valued the 42s at all ?"

Other people will surely think differently, but in my own personal opinion, yes, an "upgraded" 42S is less valuable than an original, unhacked one.

From a collector's perspective, this should be obvious. The machine is always worthier with its original components and intact cosmetics than it can ever be with replaced chips and the unavoidable cosmetical side effects of the modification.

Plus, from both a collector's and a user's perspective,

  • You can never be 100% sure that the modification was properly done and the machine is 100% stable, and what effects it may have on the machine's stability in the long run.

  • Perhaps it will develop some bad RAM locations and you'll be getting corrupted results from time to time without even noticing it, or even worse, lose all 32 Kb of painstakingly entered programs without ever knowing if it was the modification or something you did wrong.

  • Perhaps you'll notice batteries running down much quicker than before, due to greater power comsumption caused by the newly installed, non-original RAM chip.

  • Perhaps you'll notice the machine runs noticeable slower, as the operating system has to move to and fro much larger blocks of RAM than before when editing, for instance, so you'll begin to experience a nasty effect similar to the much dreaded 'garbage collection' ...

In a word, I would never "upgrade" one of my own 42S, and I would never buy an "upgraded" 42S except at a really bargain price (say no more than US$ 50 or so), and then only to be used as an instructional or demo machine, never for real-life, professional use. Any higher a price and I'd rather spend more and buy the real, original, unhacked machine.

It's also the case that I think that 7 Kb are more than enough for such a calculator. Any problem requiring more RAM than this, I would use one of my HP-71B (160 Kb) which has a much better and convenient keyboard (specially for alpha input) and a much higher-level language and instruction set (specially with the Math ROM), not to mention full I/O. That failing, I'd use one of my laptops (768 Mb RAM). For the kind of applications the HP42S is best, 7 Kb are more than enough.

But this is just my opinion, I'm sure lots of people would do or pay whatever was necessary to upgrade and would be perfectly happy to get or buy such a machine, though I'm inclined to think they'd intend it for use, not to collect, and they aren't afraid of relying on it for professional practice, where legal liabilities are a big concern and a hacked machine which produces wrong results can result in big trouble.

Last, there's also the inescapable fact that an unhacked HP42S retains the potential to be hacked, if deemed necessary, at a future time, while a hacked 42S can never revert to its original, pristine condition, so you've indeed lost something.

Best regards from V.

                  
(edited)Based on my own experience... (was: HP42s memory upgrade)
Message #18 Posted by Vieira, Luiz C. (Brazil) on 7 Feb 2005, 1:00 p.m.,
in response to message #17 by Valentin Albillo

Hi Valentin, folks;

allow me to add a few info to your comments?

Quote:
Perhaps you'll notice batteries running down much quicker than before, due to greater power comsumption caused by the newly installed, non-original RAM chip.
In fact it may happen, but if you use low-power 32KRAM chips the power consumption is almost the same. In my case, I used a 32KRAM removed from a broken, LCD-less HP48G. I measured the current with an instrument that was able to read up to 199.9mA. The readings with both original 8KRAM and hacked 32KRAM when turned to OFF and later to ON were the same with this instrument. I guess that if the RAM chip is not a low-power type, chances are you'll see the higher consumption and, consequently, batteries not lasting longer than usual.
Quote:
Perhaps you'll notice the machine runs noticeable slower, as the operating system has to move to and fro much larger blocks of RAM than before when editing, for instance, so you'll begin to experience a nasty effect similar to the much dreaded 'garbage collection' ...
This is a fact. If a program is large and it constantly accesses data in higher addresses (like the last elements of a 4040 complex matrix), you'll notice the calculator slows down.

Just my 2.

Luiz (Brazil)

(P.S. - maximum square matrices for a hacked, 32KRAM HP42S:

SIZE 0000
[6262 Matrix], 1004 bytes free memory
[4444 Cpx Matrix], 780 bytes free memory
Maximum size, nothing else in RAM: 3,967!)

Edited: 7 Feb 2005, 1:32 p.m.

                        
Re: Based on my own experience... (was: HP42s memory upgrade)
Message #19 Posted by Erik Ehrling (Sweden) on 8 Feb 2005, 3:50 a.m.,
in response to message #18 by Vieira, Luiz C. (Brazil)

In reality the theoretical slow-down should not be a problem. The garbage collection, for example, is internally the same as on the HP-28S which has the same CPU and 32K RAM already.

The only slow-down I have experienced in reality is when editing large programs that reside in memory at the same time as memory is full of programs; then entering one program line takes a notifiable long time (haven't measured it, but could be up to a second or so...). This is probably because the HP-42S has to copy all other programs x bytes in memory in order to make room for the new program line.

Best regards,
Erik Ehrling (Sweden)

                  
Re: HP42s memory upgrade
Message #20 Posted by Michael on 7 Feb 2005, 6:37 p.m.,
in response to message #17 by Valentin Albillo

Just for the record my upgraded 42s isn't for sale so it doesn't really matter about its value, I just thought I would ask the question. I did use one that had a slight ding below the lcd so it didn't matter so much anyway, and it is one that I use all the time. I wouldn't do it to one of my better units, but I am glad that I did carry out the upgrade.

I used a chip that was kindly donated to me by a complete stranger to me from this site (thanks again) which was removed from an hp48 "W24257S-70LL". I would post a photo if I knew how.

Michael

                        
Re: HP42s memory upgrade
Message #21 Posted by Vieira, Luiz C. (Brazil) on 7 Feb 2005, 7:42 p.m.,
in response to message #20 by Michael

Hi, Michael;

the 32KRAM you mentioned (W24257S-70LL) is a Winbond IC, right? AFAIK, Winbond IC's are reliable.

And congratulations! I think the HP42S itself is something to be seen and used. The hacked 32KRAM allows some 'extravaganza'...

Best regards.

Luiz (Brazil)

                              
Re: HP42s memory upgrade
Message #22 Posted by Michael on 7 Feb 2005, 11:13 p.m.,
in response to message #21 by Vieira, Luiz C. (Brazil)

Hi Luiz,

Yes you are correct, the IC is a Winbond.

            
Re: HP42s memory upgrade
Message #23 Posted by Erik Ehrling (Sweden) on 8 Feb 2005, 3:56 a.m.,
in response to message #10 by Michael

Even a modified HP-42S seems to reach fairly high prices on eBay, though...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=58039&item=5748846498&rd=1

Best regards,
Erik Ehrling (Sweden)

                  
Re: HP42s memory upgrade
Message #24 Posted by Thomas Okken on 9 Feb 2005, 7:45 a.m.,
in response to message #23 by Erik Ehrling (Sweden)

> Even a modified HP-42S seems to reach fairly high prices on eBay, though...

Yes, that 42S eventually sold for US$307.50 - that's a price that recent 42S auctions have only reached for "like new" or NIB units. So, I rest my case, a memory expansion does not reduce the value as long as there are buyers who value the increased usefulness over the decreased authenticity...

BTW, is it just me or is the 42S market on eBay starting to cool off? Hmmm, maybe it's time I bought a second one. :-)

- Thomas

                        
Re: HP42s memory upgrade
Message #25 Posted by Vieira, Luiz C. (Brazil) on 9 Feb 2005, 10:40 a.m.,
in response to message #24 by Thomas Okken

sshh...Quiet, please... If they hear you, prices will blow again... ;-)

Cheers.

Luiz (Brazil

                        
Re: HP42s memory upgrade
Message #26 Posted by Erik Ehrling (Sweden) on 11 Feb 2005, 3:59 a.m.,
in response to message #24 by Thomas Okken

Quote:
BTW, is it just me or is the 42S market on eBay starting to cool off? Hmmm, maybe it's time I bought a second one. :-)
Maybe you are yourself causing this - I mean people start downloading Free42 instead of buying their HP-42S off eBay... :-)

Best regards,
Erik Ehrling (Sweden)


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