FAST ! HP75C



#14

Hello all,

Just dug out a nice HP75C, working flawlessly with NiCads holding charge without problem... I love stuff that works !!

This machine is inserted in the 64K version of the Pod, so barely pocketable (it *is* for me ...), but fully extended with the additional 8K and all the Pod's functions.

I just wanted to state my amazement at the speed of that daemon. I'm well used to the HP71B, but the 75 is much much faster IMHO. What a nice machine ! Actually it's so much better that I'd happily let go the extra mathematical capability of the 71 (sorry Valentin, but I am more into number theory) for the speed. 32 characters on screen is also very welcome.

Why has this brilliant machine attracted so little followers, I wonder (OK, the price wasn't right, but it is now) ?

Just one small problem, as I got it with the Pod, the battery door is gone. Is there a source for these somewhere ?


#15

Hi,

The HP75C use the same processor than the HP85,86,87 serie and share many common design, that can explain its speed.

I'm interested by the roms of the HP75C and from the POD too (for an emulator). I can send some informations to dump the roms if needed.

Olivier


#16

OK for ROM downloading, why not, but :

- The list of tools I have is : one pencil (not sharp)

- Copyright issues I know nothing about, please sort out.

So if none of this present unsolvable problems, please use my address available inside the first message. I'd be proud to contribute anything of value to the MoHPC !

#17

Several of us are interested in knowing how to dump the 75 ROMs. Perhaps you could post the information here or in the articles forum.

Eric

#18

What are you basing the speed comparison on? Its different processor type will make it appear much faster with something like an empty FOR-NEXT loop or text work; but for doing something like an FFT, the 71 (especially with the math module) has a big speed advantage. I have both, but have hardly used the 75 at all. I don't remember that the 75 had enough memory available to do anything big anyway, whereas with my 71 with 177KB of RAM (ten times what it came with), I've done 8K FFTs many times with a lot of other things in memory.

E-mail: wilsonmineszdslextremezcom (replace the z's with @ and . )

Edited: 15 Jan 2007, 2:21 p.m.


#19

The FFT is probably coded in machine language, so the comparison is not relevant (if I'm not mistaken in saying the FFT is coded in Basic on the 75C).

My comparison was based on running some number theory programs, basically +-x/ and a few loops (as you said). On this kind of things, the 75 is vastly faster than the 71. Note that the 75 was much more expensive, and that it actually has a maximum of 24K. RAM limitation was never a problem for me, as writing more than 10K in Basic doesn't happen very often. With the Pod comes an extra 64K (or 32K for the smaller version) of RAM disk.


#20

Quote:
RAM limitation was never a problem for me, as writing more than 10K in Basic doesn't happen very often.
I don't think I ever had a program more than about 8K long, but I had scores of files in memory all the time so I seldom needed to use my mass-storage device. Then there was still a lot of room left for data. In the case of the 8K FFT I was referring to, maybe I should have said that that was 8192 points in a full-precision complex array. That takes a lot of memory. I would transfer it in over the interface from a digital oscilloscope over HPIL with the HP82169A interface converter to HPIB (IEEE-488). Since the oscilloscope's precision was only 8 bits, it would have been nice if the 71's math module's FFT function had been made to allow keeping the data in a COMPLEX SHORT array to save a lot of memory.

The math module's functions are coded in assembly, and the 71 could do FFTs twice as fast as the early IBM PC's could running GWBASIC, and the 71 could also do bigger ones than GWBASIC's memory usage limit allowed. The 75's 8-bit processor and 8-bit data bus will make the 75 inherently faster at text and limited-precision integer work (other factors being equal), whereas the 71's wide processor registers make it more efficient for floating-point math and its 4-bit data bus maximized RAM economy for storing BASIC tokens. There are others on this forum who know far more about it than I and can give us more details.

I wrote a heavily feature-loaded text editor for the 71 that took a little over 7K but used lots of LEX files which I also had in RAM. I wanted it to be very nimble at getting around in the files on the small screen without connecting the monitor. I used to do a lot of typing on it (as in meetings), and got where I could do 30wpm on its 2/3-size keyboard. I could do about 45wpm on a full-sized keyboard.

The one thing the 75 really had going for it was Visicalc. I bought Workbook71 but was disappointed with it. The writer had a lot of good ideas but probably couldn't carry them far enough without expecting everyone to have as good a collection of LEX files as I had.

The first time I saw a 75, I was captivated by its looks. The thing was beautiful! I did wonder though why they kept selling it so long after the 71 was out, because the 71 was a whole lot more powerful, accommodated a lot more memory, was half the size, and half the price.

The 71 was supposedly made for technical professionals. Yet not one in ten technical professionals even knew it existed; and of those who did, not one in ten had any idea how much power it had especially with third-party modules and LEX files. I think the marketing was very much mismanaged, and I seem to remember reading that the head of the design team was upset by what they did with his baby.


#21

Hi, Garth:

Garth posted:

    "I think the marketing was very much mismanaged, and I seem to remember
    reading that the head of the design team was upset by what they did with his baby."

      Surely you must be referring to this post to comp.sys.hp48 (18 Sep 92) by Steven T. Abell, one of the founding fathers of the HP-71B, in reply to Joseph K. Horn:

        [...] Mr. Horn, I was there when Titan (HP-71B) was born. I wrote a *very* large chunk of its ROM. I designed CALC mode. I left in August '83, and I am still furious.

        The marketeers wanted an algebraic machine. They said that selling RPN was
        just too hard. For programmability, they wanted BASIC, so that people could
        run "all that software already out there." We gave them what they wanted. It
        had what was arguably the most powerful BASIC HP had ever released on *any*
        machine up to that time. It had multiple language capability. It had multiple
        file systems. It had math and stat software to *die* for. It was radically
        extensible. And it was an algebraic calculator.

        The marketing boys ran one ad, then started complaining when they discovered
        that selling the world's most powerful calculator might mean that they had to
        do some actual work, not only in concocting new slogans, but just understanding
        the consequences of what they had demanded.

        And then there was John Young, high mucky-muck of HP and exemplar of fine
        American management, whose only question about the product was "Can you play
        PacMan on it?" He asked me this question during an official dog-and-pony show.
        I regret not calling him an imbecile to his face.

        There are several problems with a BASIC-language calculator. Management and
        marketing were warned, but paid no heed. There are limitations on what you
        can do in a one-line display (such as not running WordStar, I kid you not,
        they wanted it), but they didn't understand. So Titan was a hard sell, anyway.
        But HP marketing and management turned it into a no-sell.

        When discussing future products, the stock answers from marketing and
        management were:

        "We can't do that."
        "You don't understand: you're an engineer, not like a real user."
        "We can't do that."
        "What housewife will ever use that feature?"
        "We can't do that."
        "Will it run CPM software?"
        "We can't do that."

        Prior to my exit, we had discussed personal databases, handwriting analysis,
        cellular radio, and most of the other stuff that Apple is trying to make into
        a Newton. We had a mockup of the HP-95LX floating around the lab in 1983.
        All killed by management and marketing, who were busy designing products for
        "real users" and then going to work for Apple, where they probably didn't do
        much useful work either.

        If you like your 48, thank Bill Wickes. I regret that I didn't stick around to
        work for him, but, quite frankly, I didn't think he could keep the HP goons at
        bay. Symbolic math is, after all, one of those things that "real users" don't
        use.

        That Titan was born when the stars were askew is arguable. The problem
        was very complex, and it started and ended with HP marketing decrees. [...] taken as a whole, it's still the most
        powerful handheld computer that's ever been made.

Best regards from V.

#22

Quote:
Surely you must be referring to this post to comp.sys.hp48...

Thankyou. That was very informative and more complete than what I had read before. But no, I've never been on comp.sys.anything. What you posted is one of those things that makes one kind of angry for the right reasons, like the movie "Tucker."
#23

Hi, Garth:

Garth posted:

    "In the case of the 8K FFT I was
    referring to, maybe I should have said that that was 8192 points in a full-precision complex array. That takes a lot of
    memory. I would transfer it in over the interface from a digital oscilloscope over HPIL with the HP82169A interface
    converter to HPIB (IEEE-488). Since the oscilloscope's precision was only 8 bits, it would have been nice if the 71's math
    module's FFT function had been made to allow keeping the data in a COMPLEX SHORT array to save a lot of memory."

      If your input was a purely real-data sequence, I suppose you were aware at the time that there's a simple "trick" that will allow you to compute a 2N-point purely real-data FFT by computing a 2N-1-point complex FFT and adequately splitting the complex result, right ?

      Doing that would require half the memory (and roughly half the running time as well) compared to committing the real data to a complex array with imaginary parts zeroed in order to compute the FFT. This would be similar to the savings of being able to use COMPLEX SHORT instead of COMPLEX.

      Also, as it seems that you're fond of FFT as implemented in the HP-71B Math ROM's FOUR keyword, perhaps you would like to have a look at the amusing use I made of it in this article o'mine (which you can freely download in PDF format from my web site):

        HP-71B Fantastic FOUR:

          8-page article, which discusses how you can use Fast Fourier
          Transforms (FFT) to multiply two very high-precision
          numbers faster than with any other algorithms currently
          known. Includes a very short, 10-line subprogram (can be
          formatted to just 8 lines) which will accept two numbers up to
          1024 digits long and ouput their product (up to 2048 digits
          long). Running time is nearly linear in the size of the inputs
          compared to quadratic times for the usual 'school' algorithm
          (for instance, multiplying two 512-digit numbers using FFT is
          already 4 times faster on the HP-71B than with the usual
          method). Examples included.

Best regards from V.

#24

Hello!

Quote:
Why has this brilliant machine attracted so little followers, I wonder (OK, the price wasn't right, but it is now) ?

When I needed a replacement for my Ti-59 (which had developed the ususal keyboard problem and been out for repair already) in 1985 or '86, the hp-Basic-handhelds were my "dream-candidates" of course.

I tried them out at an office-supply store for quite some time and also compared them to various Sharp- and Casio-Basic-programmable-calculators that I borrowed from friends. Apart from being an order of magnitude (one full power of ten! - at least in Germany) more expensive than the nearest competitor, the hp-75 was slightly un-ergonomic in my view: Too big for a real pocket calculator, no number-keypad for real calculations, but the alpha-keyboard still too small for quick text entry.

In the end, this is what I bought for the money that I would have had to spend for the '75: One second hand Hp-150 touchscreen PC for my desk, together with a heap of accessories (including daisywheel printer and an Hp9872C flatbed plotter - all still in my posession and working :-) ); one Casio FP-200 basic programmable "pocket" (not really...) calulator with a proper keyboard for text entry and an external number keypad; and a Ti-30 to take along as a pocket calculator.

Greetings, Max


#25

Interesting !

I think I recall the FP-200 as (relatively) very expensive compared to smaller BASIC models like the Sharp PC1350, so your choice is very un-conventional IMHO (while for text entry it makes perfect sense, despite limited RAM).

My explanation for the lack of success of the 75 would be that the price reserved it to managers, who had no clue about the technical excellence of the product, hence not justifying it. Technical types couldn't afford the machine. I sure could not afford ANY HP at the time, so I got the TI30... :-)


#26

Hello!

Quote:
1. I think I recall the FP-200 as (relatively) very expensive compared to smaller BASIC models like the Sharp PC1350, so your choice is very un-conventional IMHO (while for text entry it makes perfect sense, despite limited RAM).

2. My explanation for the lack of success of the 75 would be that the price reserved it to managers, who had no clue about the technical excellence of the product, hence not justifying it. Technical types couldn't afford the machine. I sure could not afford ANY HP at the time, so I got the TI30... :-)


1. Yes, it was very expensive originally. But when they noticed that they couldn't sell them for that price, they sold off all remaining FP-200s for bargain prices. I recall paying something like 300 German Mark (around 150 $ US) for the machine, which made it less expensive than the Basic-handhelds of Casio and Sharp! Today, it is probably worth more on eBay than I paid then :-)

2. But what would a manager do with an hp-75 that needs to be programmed first?

Greetings, Max


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