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Build Your Own HP41C | Hackaday



There was a time when designers lugged slide policies. After that there was a time when all of us lugged calculators. Certain, calculators are still about, yet you are more probable to utilize your phone. If you truly require major number crunching, you’ll rely on a complete computer system. Yet there was that unpleasant time when calculators were really essential as well as computer systems were really pricey that calculators attempted to be what we required from full-on computer systems. The HP41C was most likely the peak of that fad. If you have actually ever before had one, you recognize that is a wonder of the day’s modern technology with alphanumeric abilities as well as 4 plug in ports for even more memory or ROMs. It truly was a little hand-held computer system. Really did not have one? Do not fret, you cannow build your own As a matter of fact, the HP emulator will certainly additionally imitate an HP15C or 16C, if you like.

You can see the gadget at work in the video clip listed below. As you may anticipate, this variation makes use of a through-hole ATMEGA328 as well as also at 8 MHz, the emulation is much faster than the initial calculator. The device additionally has more than dual the memory the initial calculator had together with a real-time clock built-in. The screen is additionally backlit, something all of us desired in the initial.

What we truly suched as, however, was the 3D published situations you can download and install for the calculators. You can see that in the video clip, also. We were a little depressing that the set remains in an HP15-C like landscape alignment unlike the HP41’s picture style. However, the schematics exist so possibly somebody will certainly outline a good HP41-specific board.

Certainly, HP calculators utilized RPN, yet if you matured with a slide guideline that’s penalty. For everybody else, it is normally a little a discovering contour. Likewise, as fantastic as the HP41C was, it really did not have binary or hex and even octal mathematics unless you utilized “artificial shows” as well as though we think of the emulators utilized can take care of artificial shows (type of setting up language for the HP41C) it was never ever enjoyable to work with non-decimal troubles with this device. Still, what a terrific calculator as well as it is enjoyable to see it born-again in modern-day kind.

We have actually seen an additional phony HP41C that we assume is utilizing the very same emulation software program yet needed SMD soldering. We question if the KIM Uno or 1802UNO could be made to operate on the very same equipment? Feels like it would certainly.

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Building The DIY HP41C: A Field Report




I have an admission to make. I discuss a great deal of tasks for Hackaday, yet there are really couple of I review and afterwards go really develop a duplicate of it. I do not have a great deal of time as well as I’m generally also hectic constructing my very own things. Once in a while, something strikes my fancy as well as I’ll either plunder the scrap box or acquire the package. One of the most current situation of that was the PX-41C, a reproduction of the traditional HP-41C.

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Perfectly nabbed components.

The HP-41C is a rather famous reverse-polish symbols calculator. I still have my initial HP-41C from 1979( an extremely reduced identification number). It is still a workhorse yet at 43 years of ages approximately, I do not such as to leave it spending time or near anything that could harm it. It has sufficient use from the everyday usage it obtained 40 years earlier. Certain, I have fantastic emulation on my phone as well as I make use of that also, yet the PX-41C package looked enjoyable, as well as with all through-hole components it would certainly be a fast develop. The black Friday sale

secured the bargain for me.

Startupon Tindie The package showed up on the Saturday after Thanksgiving, I made a decision to tackle it while waiting on some 3D prints. The parts were all well landed as well as noted. Tearing right into the bags was a little bit irritating, yet not tough as well as it did maintain every little thing different. There was a costs of products, yet– I believed– no guidelines. Ends up the tail end of the costs of products is a web link to some guidelines. They aren’t much as well as I really did not understand they were up until after finishing the board, yet it isn’t tough to identify. All the components are noted on the silkscreen as well as you can possibly figure it out– with a couple of cautions.

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Keep in mind parts compressed down for the LCD.

A number of parts go under the LCD present which is soldered in, so you require to place them in initially. I asked yourself if you must mount them on the back of the board, yet the images revealed them front-mounted as well as you understand rather promptly you need to flex them to allow the LCD rest level. The guidelines, if you review them, do state this.

Once I had every little thing yet the changes done, I powered approximately see to it all of it functioned. It did– or, a minimum of– it powered up as well as stated MEMORY LOST.


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With 39 buttons, you require 156 solder joints …

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With 39 buttons, you require 156 solder joints …

There are 39 little tact changes to mount. Thankfully, they have little legs that spring right into the openings, so it isn’t really tough. Nevertheless, they can bulge, so I recommend doing a column or 2 at once. One button was a little curved out of form yet there was an additional, so I really did not trouble attempting to unbend it.

With a couple of type in the lower appropriate edge, I might power on as well as do a couple of fast estimations without trouble. The board takes a CR2025 as well as I just had a thinner battery. A penny made an excellent spacer as well as allow me fit the slim battery as well as obtain the important things functioning.


The board has a backlit LCD as well as a clock– includes a routine HP41C really did not have. Nevertheless, I really did not see an apparent means to establish them. I had actually discovered the documents already as well as it stated to hold the 0 secret while powering on enter into the setup food selection. Ends up, it is the divide secret, which took a min to identify. Furthermore, the tricks to run the food selection system are a little rickety( yet, in all justness, the firmware placed an aid message on the display up until you launch the divide secret ).

Simply in Situation

< img data-attachment-id=" 509452" data-permalink="" data-orig-file="" data-orig-size= "863,928" data-comments-opened =" 1" data-image-meta=" {" aperture":" 0 "," credit report ":"", "video camera":" "," inscription":""," created_timestamp": "0 "," copyright":"", "focal_length":" 0 "," iso":" 0"," shutter_speed":" 0"," title":"", "alignment ":" 0"} "data-image-title =" kitcase" data-image-description ="" data-image-caption=" (* )The situation looks fantastic as well as the essential springtimes are really accurate. The tape on the overlay is really noticeable in the picture, yet not as poor personally.

” data-medium-file=”″ data-large-file=”″ loading=” careless” course=” size-medium wp-image-509452″ alt”=””” size” =” 372″ elevation=””” 400″ srcset=” “ 863w,”,250 232w,,400 372w,,625 581w” dimensions=”( max-width:””372px) 100vw, 372px””/”>(” *) The situation looks fantastic as well as the essential springtimes”are really” accurate. The tape on the overlay is really noticeable in the picture”, yet not as poor personally.

There is a 3D published situation as well as a method to publish an overlay for the tricks together with a bouncy essential matrix.
They behaved sufficient to send me these currently comprised, although I’m not exactly sure that’s constantly consisted of. The overlay looks fantastic in the beginning, yet if you look carefully, it is taped down which takes away a little from it. Do not raise the tape! It will certainly destroy the overlay.

The situation looked excellent, as well as it is rather basic. There were a couple of troubles, however. Initially, the LCD was jabbing up at an angle. The guidelines inform you to tape it to the CPU, yet that really did not actually assist. After taking these images, I drew the LCD off as well as re-installed it very carefully with brand-new headers as well as had it appear great as well as flush.

The various other trouble was that the R/S type in the lower appropriate edge really did not wish to deal with the situation in position. Occasionally it was defective. Occasionally it would certainly function yet really did not click like the remainder of the tricks as well as was a lot more like a touch panel. Occasionally it was stuck weighed down.

I attempted submitting the situation a little yet that really did not appear to assist. There are some nubs that maintain the board from boiling down also short on the essential springtimes. It appears like the situation was distorted sufficient to have that edge a little bit less than the remainder. If you left the withdraw as well as pressed on that edge, it would certainly recreate the trouble, yet the various other edges were great. (* )I thought of reprinting the situation myself– I have sufficient 3D printers, nevertheless. However I ultimately made a little paper shim to make the drop in that edge a little thicker. I simply took a tiny strip of paper as well as folded it sometimes up until it had to do with the exact same dimension as the quit as well as placed the quit right into the paper making a sandwich where the paper was the bread as well as the quit was the meat. This appears to have actually improved the key-board concern. It does not appear like the trouble was associated with the essential installment, yet anything is feasible. I’m rather certain it was simply a refined bending in case.

Last Perceptions

< img data-attachment-id=" 509455" data-permalink="" data-orig-file="" data-orig-size=" 1292,927 "data-comments-opened =" 1 "data-image-meta=" {" aperture":" 0 ", "credit report ":"", "video camera ":""," inscription ":""," created_timestamp":" 0 "," copyright ":""," focal_length ":" 0", "iso":" 0"," shutter_speed":" 0 "," title":""," alignment ":" 0"} "data-image-title=" kitdone "data-image-description =" "data-image-caption ="(* )Done. Kind of. Functions fantastic!

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Done. Kind of. Functions fantastic! The tape is really reflective in pictures.(” *) For the cost( concerning$ 40 )this is an enjoyable package as well as is really beneficial. It”would certainly behave if””the LCD had a”outlet.”It would certainly additionally behave if the overlay mount looked cleaner, but also for a”laid-back glimpse,”it is great as well as it still looks far better”than simply a bare PCB with tricks– unless you”like that kind of point.

I”have not attempted to see if the emulator will certainly”do artificial programs yet”, yet it gets on”my to do checklist. ” Or else, I currently can”utilize my HP41C without phone as well as without risking my genuine one. After forty-some-odd years, it can make use of the remainder.

For one reason or another, the tasks I have a tendency to develop after composing( or analysis) concerning them are mainly for retrocomputing. I developed the KIM UNO( as well as repurposed it for the 1802). I developed a PiDP-8( as well as require to discover time for the PDP-11 variation). Perhaps my fave was the$ 4 Z80 which I really

, software-wise.

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Hacking An Obsolete Yet Modern Calculator




The gold requirement for graphing calculators, a minimum of in the United States, are the Texas Instruments TI-84 collection. Some outcast might have various other kinds, however mostly because of standard screening these calculators control the marketplace. Additionally due to standard screening, these calculators have actually stayed basically unmodified for years. While this isn’t fantastic for obtaining worth for cash, it does mean that generations of students have been able to hack on these calculators to do all kinds of interesting things as [George Hilliard] outlines.

Also prior to the development of these graphing calculators, the z80 cpu behind them was initially generated over 4 years back and also was common in the computer system scene at the time, which additionally provides to its hackability. There’s lots to capture up on right here, as well, from personalized TI video games that deceive the two-tone display screen right into grayscale to Video game Kid emulators that can play Zelda given that the TI and also Video game Kid share the exact same cpus. There are additionally numerous techniques of running indigenous code or otherwise “jailbreaking” these gadgets to run approximate code.

It appears like the globe of TI hacking lives and also well currently, and also with numerous years of jobs to search there’s constantly something brand-new to locate. As it stands, there might be extra years of these sorts of jobs to find, given that neither TI neither the numerous screening standardization firms and also federal government companies reveal any kind of indications of transforming whenever quickly.

Many Thanks to [Adrian] for the idea!

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