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DIY Calculator
04-08-2019, 11:01 PM
Post: #1
DIY Calculator
Hi,

I putting together a kit to build a pocket HP RPN style calculator and would like to get feedback as to what to add or remove.

The basic idea was to make a kit anyone could build using standard, off the shelf thru-hole electronic components.

Current features:
• 64 bit (IEEE 754) floating point arithmetic
• 4 stack (x, y z and t)
• 10 memories
• Trig functions (rad & deg)
• LOG, LN
• % %CHS
• Display Backlight
• auto shutdown
• long battery life with 2 AAA alkaline batteries
• SQRT, x^2, 1/X
• Conversions from metric to Imperial (length, speed, volume, mass, temp)
• Date and Time clock (has watch crystal)
• FIX, SCI and ENG Notation with comas or period separator
• Audio keypress feedback (beeps)

Please see pictures and let me know what you think.

Thanks,
-alx


https://giga.com/rpn%20calc/IMG_1333.JPG
https://giga.com/rpn%20calc/IMG_1333.JPG
https://giga.com/rpn%20calc/IMG_1334.JPG
https://giga.com/rpn%20calc/IMG_1335.JPG
https://giga.com/rpn%20calc/IMG_1336.JPG
https://giga.com/rpn%20calc/IMG_1331.JPG
https://giga.com/rpn%20calc/IMG_1337.JPG

[Image: IMG_1337-sm.jpg]
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04-09-2019, 03:09 AM
Post: #2
RE: DIY Calculator
I'll take one!

I'd recommend making it programmable to attract the biggest audience. And maybe use a key layout that would make it easy to support a 41CX emulator firmware.
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04-09-2019, 05:40 AM
Post: #3
RE: DIY Calculator
Looks very nice, good job.

What processor and development tools did you use?

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04-09-2019, 09:42 AM
Post: #4
RE: DIY Calculator
(04-09-2019 03:09 AM)Dave Britten Wrote:  I'll take one!

I'd recommend making it programmable to attract the biggest audience. And maybe use a key layout that would make it easy to support a 41CX emulator firmware.

Unfortunately there is very little memory left so making it programmable is not an option.
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04-09-2019, 09:47 AM
Post: #5
RE: DIY Calculator
(04-09-2019 05:40 AM)Dan Wrote:  Looks very nice, good job.

What processor and development tools did you use?

The micro controller used is the ATMEGA328. Programming was done in Xcode.
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04-09-2019, 11:22 AM
Post: #6
RE: DIY Calculator
(04-09-2019 09:42 AM)agarza Wrote:  
(04-09-2019 03:09 AM)Dave Britten Wrote:  I'll take one!

I'd recommend making it programmable to attract the biggest audience. And maybe use a key layout that would make it easy to support a 41CX emulator firmware.

Unfortunately there is very little memory left so making it programmable is not an option.

Hey, if Sinclair can make a programmable scientific calculator with half the ROM of an HP-35, then a 32KB AVR should be no sweat! ;D

Since it's an AVR, I would suggest including a USB programming port (would that model require an external USB-to-TTL chip?) and leaving the Arduino bootloader on it. It would make for a very nice platform for experimentation.
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04-09-2019, 03:25 PM
Post: #7
RE: DIY Calculator
(04-09-2019 11:22 AM)Dave Britten Wrote:  
(04-09-2019 09:42 AM)agarza Wrote:  Unfortunately there is very little memory left so making it programmable is not an option.

Hey, if Sinclair can make a programmable scientific calculator with half the ROM of an HP-35, then a 32KB AVR should be no sweat! ;D

Since it's an AVR, I would suggest including a USB programming port (would that model require an external USB-to-TTL chip?) and leaving the Arduino bootloader on it. It would make for a very nice platform for experimentation.

I have no idea how Sinclair did such a feat. I have run out of memory.

You can use the Arduino IDE and program it with an Arduino Uno, usbtiny or usbasp. If you look at the pictures, on the back you'll see there is a 6 pin programming connector.
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04-09-2019, 04:55 PM
Post: #8
RE: DIY Calculator
I would like one.
Count me in.

Which key sequence is arctan, arcsin, arccos?

J

Jaco Mostert, Elec Eng
42S, DM42, WP34C/S, 28C, 35S, 32Sii, owned 11C; used 67, 85; iOS: 42s, Free42, WP31S/34S, HCalc; OSX: WP34C.
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04-09-2019, 05:03 PM
Post: #9
RE: DIY Calculator
(04-09-2019 04:55 PM)Jaco@cocoon-creations.com Wrote:  I would like one.
Count me in.

Which key sequence is arctan, arcsin, arccos?

J

There are two ways.

For example:
Pressing the "shift" SIN gives you ASIN.

Or by selecting the virtual buttons of ASIN, ACOS and ATAN.
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04-09-2019, 05:35 PM
Post: #10
RE: DIY Calculator
(04-09-2019 03:25 PM)agarza Wrote:  I have no idea how Sinclair did such a feat. I have run out of memory.

That's easy. Whips.

Actually, it's probably because they wrote entirely in assembler, if not in machine language when a shoehorn was really needed, plus had many programmers with lots of experience writing close to the hardware (they had no other choices at the time).

Not casting any aspersions towards you, I've no idea at all of your experience, but these days writing hand-tuned and optimized assembly language for a custom CPU is extremely rare and simply not justifiable.

--Bob Prosperi
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04-09-2019, 05:43 PM
Post: #11
RE: DIY Calculator
(04-09-2019 05:03 PM)agarza Wrote:  
(04-09-2019 04:55 PM)Jaco@cocoon-creations.com Wrote:  I would like one.
Count me in.

Which key sequence is arctan, arcsin, arccos?

J

There are two ways.

For example:
Pressing the "shift" SIN gives you ASIN.

Or by selecting the virtual buttons of ASIN, ACOS and ATAN.

Please see the video:
calculator movie

And let me know what you think.
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04-09-2019, 06:49 PM
Post: #12
RE: DIY Calculator
Thanx (re ASIN etc.). I did initially not see the shift button.
Video looks great.
Do you have the kits available?
J

Jaco Mostert, Elec Eng
42S, DM42, WP34C/S, 28C, 35S, 32Sii, owned 11C; used 67, 85; iOS: 42s, Free42, WP31S/34S, HCalc; OSX: WP34C.
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04-09-2019, 07:12 PM
Post: #13
RE: DIY Calculator
(04-09-2019 06:49 PM)Jaco@cocoon-creations.com Wrote:  Thanx (re ASIN etc.). I did initially not see the shift button.
Video looks great.
Do you have the kits available?
J

Yes, I have kits available.

I'm now in the process of design the case. Anyone has experience designing/printing calculator keys and case?
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04-09-2019, 07:16 PM
Post: #14
RE: DIY Calculator
(04-09-2019 07:12 PM)agarza Wrote:  
(04-09-2019 06:49 PM)Jaco@cocoon-creations.com Wrote:  Thanx (re ASIN etc.). I did initially not see the shift button.
Video looks great.
Do you have the kits available?
J

Yes, I have kits available.

I'm now in the process of design the case. Anyone has experience designing/printing calculator keys and case?

How do I order?
How much does it cost?
J

Jaco Mostert, Elec Eng
42S, DM42, WP34C/S, 28C, 35S, 32Sii, owned 11C; used 67, 85; iOS: 42s, Free42, WP31S/34S, HCalc; OSX: WP34C.
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04-09-2019, 08:45 PM
Post: #15
RE: DIY Calculator
(04-09-2019 07:16 PM)Jaco@cocoon-creations.com Wrote:  
(04-09-2019 07:12 PM)agarza Wrote:  Yes, I have kits available.

I'm now in the process of design the case. Anyone has experience designing/printing calculator keys and case?

How do I order?
How much does it cost?
J

If anyone is interested in a kit please PM me.

Thanks.
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04-09-2019, 10:55 PM
Post: #16
RE: DIY Calculator
(04-09-2019 07:12 PM)agarza Wrote:  I'm now in the process of design the case. Anyone has experience designing/printing calculator keys and case?

Craig Bladow designed an excellent 3D case/keys in 2018 for the NP-25 Emulator Chris Chung designed several years ago.

Here's the thread:

http://www.hpmuseum.org/forum/thread-217...#pid103503

--Bob Prosperi
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04-10-2019, 02:20 AM
Post: #17
RE: DIY Calculator
(04-09-2019 10:55 PM)rprosperi Wrote:  
(04-09-2019 07:12 PM)agarza Wrote:  I'm now in the process of design the case. Anyone has experience designing/printing calculator keys and case?

Craig Bladow designed an excellent 3D case/keys in 2018 for the NP-25 Emulator Chris Chung designed several years ago.

Here's the thread:

http://www.hpmuseum.org/forum/thread-217...#pid103503

Thanks
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04-10-2019, 05:31 AM (This post was last modified: 04-10-2019 05:32 AM by Dan.)
Post: #18
RE: DIY Calculator
(04-09-2019 05:35 PM)rprosperi Wrote:  These days writing hand-tuned and optimized assembly language for a custom CPU is extremely rare and simply not justifiable.

I did for the AriCalculator. It was the first large project I coded in assembly.

And the last.

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04-10-2019, 06:38 AM
Post: #19
RE: DIY Calculator
(04-09-2019 03:25 PM)agarza Wrote:  
(04-09-2019 11:22 AM)Dave Britten Wrote:  Hey, if Sinclair can make a programmable scientific calculator with half the ROM of an HP-35, then a 32KB AVR should be no sweat! ;D

Since it's an AVR, I would suggest including a USB programming port (would that model require an external USB-to-TTL chip?) and leaving the Arduino bootloader on it. It would make for a very nice platform for experimentation.

I have no idea how Sinclair did such a feat. I have run out of memory.

Here is how Sinclair's Nigel Searle achieved a scientific calculator (non-programmable) in under 320 words of code.
http://files.righto.com/calculator/sincl...lator.html
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04-10-2019, 02:02 PM
Post: #20
RE: DIY Calculator
(04-10-2019 06:38 AM)Steve Simpkin Wrote:  
(04-09-2019 03:25 PM)agarza Wrote:  I have no idea how Sinclair did such a feat. I have run out of memory.

Here is how Sinclair's Nigel Searle achieved a scientific calculator (non-programmable) in under 320 words of code.
http://files.righto.com/calculator/sincl...lator.html

Oh right, it was the Scientific that was 320 words, not the programmable models. But I'm sure the Sinclair Cambridge Programmable had a super tiny ROM too.
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