HP 67 vs. HP 65 display


I finally got myself an HP 67. I cleaned it up, replaced a corroded battery terminal and did the card reader repair. Everything is working now. But I am surprised by how much brighter the HP 65 display is compared to the HP 67. Is this intentional?
Also it is slower than the HP 65 which was not what I expected.



Hi Harald, I can guess that maybe the dullness is deliberate to increase LED life ?

What do you mean by the 67 being slower than the 65 ?



Hi Harald, I can guess that maybe the dullness is deliberate to increase LED life ?

That's what I thought, too. But I am not sure. The display driver is like the one in the woodstocks, not the classics. Just not sure why.

What do you mean by the 67 being slower than the 65 ?

Sorry, that probably was a bit confusing in the context. Programs run slower on the 67 than they do on the 65. I did a little "benchmark" earlier [url: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv021.cgi?read=214671#214671] and ran the same program on the 67 now. I will post results later.

Maybe this is to save battery too.


As you can see in the HP Museum page about the -67, this calculator is based on Woodstock technology, despite its Classic body. It also needed to be program-compatible with the -97; and that may have had some impact on firmware complexity. I don't have a -67, but I think it has the same "evolution level" algorithms than the -29 [i.e., operations like (-2)^3 are allowed], and the addressing schema for program lines is more sophisticated that the one in the -65; so all these issues may impact the performance of some (or many) programs.


Ok, I have added the times for the HP67 to the list posted here:

Program 1 to 100 takes 50s
Program 2 to 100 takes 37s

The first thing that is odd is that the factor between the two is 1.35 as opposed to the 1.45 observed on the HP 29C and WP 34S.

So the index would look like this:

WP-34S: 1
HP-15C LE: 3
HP-33S: 15
HP-32SII: 28
HP-35S: 48
HP-42S: 78
HP-41CV: 176
HP-65: 248
HP-29C: 295
HP-25: 295
HP-12C CR2032:307
HP-12C LR44: 322
HP-67: 388 / 420
HP-15C (old): 490

Pretty slow compared to the other woodstocks.

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