HP 65 Card writer compatibility testing

[carolinahomes]

Earlier this week I was talking with someone who backed out of the idea, so the search continues and I thought I'd post this here:
Who here would like to mail user-programmed cards back and forth to one another to test the compatibility of their recently restored HP card writer functionality?
I've written 5 cards and sealed them separately along with what each card is supposed to do, you'll receive them, test them in your 65, let me know if they work, then mail them back in the self addressed stamped envelope. (My cards are in very pristine condition: no writing, dirt, smudges, oils and are not clipped.)
And then I'll do the same for your cards.
This way we can be more assured that our repair jobs are lined up within original spec.

I'd prefer to keep the shipping destinations within the continental USA.

[John Garza (3665)]

I've never had a problem with compatibility among multiple machines.
Can your machine read the prerecorded cards as in the Standard Pac?

-J

[carolinahomes]

(08-16-2023 05:30 PM)John Garza (3665) Wrote:  I've never had a problem with compatibility among multiple machines.
Can your machine read the prerecorded cards as in the Standard Pac?

-J

I have 5 various pre-recorded Pacs and while I have not yet tested every single card (there's about 150 total here), only 1 so far is missing data due to damage. But that test merely has to do with the reader's functionality.
I wish to test the writer's full functionality and so far everything seems to be factory-perfect once again.

My hypothesis is that there are some machines that are not compatible with others. This is the only way I know which to properly test whether it's true or not.

[teenix]

(08-16-2023 06:31 PM)carolinahomes Wrote:  My hypothesis is that there are some machines that are not compatible with others. This is the only way I know which to properly test whether it's true or not.

After all these years, it's remarkable that this system still works at all.

There would have been speed variation factors considered originally, different calculators, temperature, humidity, phase of the moon etc. I would think, assuming the read and write functions are ok, then the only errors would be either a slow/fast running motor or the CPU board master timing is out of spec due to component aging etc. These errors may not impact a user that doesn't swap cards, and the errors may not even be known, but as you say, they may not work in another machine.

Assuming both cards work fine in their own 65's, I guess the question then is, if they don't in another 65 which one is at fault.

One good thing about swapping cards is that you cannot spread a calculator virus ;-)

cheers

Tony

[rprosperi]

Can you clarify the point of this suggested process, which I and others are missing, other than perhaps having some retro fun?

As long as your 65 reads the cards your 65 writes, that's probably all you really need, right?

I mean, it's not as if you'll be meeting with members at a weekly PPC meeting and exchanging program cards as a quick and easy way to share programs... unless it has suddenly become 1976 again, in which case this message isn't possible...

Don't get me wrong, retro fun is fine, and in fact stuff like this really is fun, it just sounds more dire than just play.

[John Garza (3665)]

Well... you CAN spread malicious code.
But its easy to erase by switching OFF.

All the 65s should be compatible as they came with prerecorded cards and multiple 'Pacs' available that can be read by any machine. If the machine wrote to a different standard, the card it created would not be readable by the same reader that reads the prerecorded cards.

The mechanism is self-clocking within limits. Some minor variation can be handled.
Not a surprise to me they still work. HP had good MEs as well as EEs !

The TI machines... well, that's another story. I have had TI-59s that could not share cards. Usually just tweaking the card speed pot fixes that.

For the proposed experiment - what would be a statistically significant sample size? How many working HP-65s are still around? Are the hypothesized failures normally distributed (as in new products) or perhaps some other more obscure curve due to aging components and mechanical wear?

I did something similar last winter. I wrote a simple wind chill program and wrote/read it across all six of my working HP-65s. They all worked perfectly.

-J

[carolinahomes]

(08-16-2023 10:06 PM)John Garza (3665) Wrote:  I did something similar last winter. I wrote a simple wind chill program and wrote/read it across all six of my working HP-65s. They all worked perfectly.

-J

Well, this is wonderful to hear. Six working units do help to support the conclusion that 65's are quite compatible with one another.

This idea is for my own personal peace of mind. Whether anyone cares to join in, well that's not exactly up to me, but I am hopeful that someone may want to. If anyone reads this wants to do so, look me up. For background info, my ebay handle is carolinahomes and I am still living in the 80's for the most part.

[carolinahomes]

(08-16-2023 10:06 PM)John Garza (3665) Wrote:  I wrote a simple wind chill program...
-J

By the way, that wind chill program you wrote, does it resemble this:

23
11
33 01
31
07
83
02
05
02
02
71
83
06
05
00
05
61
33 03
35 07
33 02
34 03
31
07
01
01
08
83
08
71
02
83
00
03
08
42
61
33 04
34 02
34 03
71
34 04
51
33 05
34 02
35 07
35 24
22
00
34 05
23
01
21
83
00
24
23
00
34 02
22
01
24
23
12
09
71
05
81
03
02
61
24
23
13
01
83
01
05
71
24
35 01 the rest of the way.

I've only just begun to dive into the older user-programmed cards I have, and this is one of them that happens to be for wind chill factor.

[John Garza (3665)]

No, mine is different. At first I thought to try the algorithm in 'Algorithms for RPN Calculators'. But that is wildly different than the equations you can find via Google.

Code:


* Lbl A {store ambient temp in degrees F}
Sto 1
Rtn
* Lbl B {store wind speed mph}
Sto 2
Rtn
* Lbl E {calculate effective temperature degrees F}
35.74
Enter
Rcl 1
.6215
X
+
Rcl 2
.16
Y^X
35.75
X
-
Rcl 2
.16
Y^X
Rcl 1
X
.4275
X
+
Rtn

Test Case:
47 degF at 14 mph is 41.07 degF effective temp

-J