RIP Radio Shack EC-4013 Calculator

I got this calculator in high school back in 19something… a long time ago. I used it in calculus, college physics, statistics, last semester’s chemistry class… it was the calculator I grew up on.

A few weeks ago, some of the buttons on the fold-out section stopped working. It’s very sad but calculator microsurgery isn’t a priority.

(UPDATE 7-1-23: Find nostalgic conversations and the manual in the comments below!)


  1. Greg says:

    I have the same calculator!!! I bought it in 1985.
    I have the same problem with some buttons on the right side pad.
    The quality is excellant!

  2. Mike says:

    The problem is with the ribbon connecting left and right side, which is hiden under welded plastic cover. Some of the metal path are broken due to folding and unfolding the cover. I can’t understand the manufacturer’s policy (Sharp?) not to continue production of one of the best scientific calc tools.

  3. Kristi says:

    It must be a cosmic conspiracy. I just googled Radio Shack EC-4013 because the 3 key has started not registering. The right hand side is fine. I purchase this calculator in 1986, my senior year in high school. It made it all the way to 2012. It has seen me through college, grad school and post doc. Its an old friend that I’m going to miss. Especially the easy metric to US standard conversions.

    Mourning a calculator. My sister is right, I’m a nerd.

  4. wle says:

    where is the battery in these things?
    i am tired of it blinking out when a shadow goes by…


  5. lee says:

    wle, sorry, dunno. I never had trouble with the battery. On mine, if you covered the solar panel, the display would shut off in like 5 seconds so the battery was more of a small capacitor. It would have to be pretty much so dark that I couldn’t see the display for the solar panel to not power it.

  6. wle says:

    battery is behind the display
    very hard to get to
    may not be able to reassemble
    snaps broke
    plus weird size battery
    but i did find it :)


  7. wle says:

    without battery, it would revert to HEX and GRAD mode or something weird every time the light went away


  8. lee says:

    Cool! Glad you found it!

  9. David Rock says:

    I got this calc in 11th grade 1985 and still using. It’s of my favorite tools. On mine the plastic at fold started splitting a long time ago. A new piece of black duct tape once in a while keeps it together. Everything works and no battery problem. Will be sad when it goes. Maybe I’ll post back here someday with it’s unfortunate demise, whatever it is :-)

  10. Lauren Scott says:

    I spent years using this calculator doing electronic design and embedded systems programming (mostly assembly lanaguage) in the 1980s and 1990s. The HEX and logical functions rock! You just don’t find those function much any more. Sadly, like many of these, the conductive traces between the right and left side failed and I was forced to abandon it sometime in the late 1990s.

  11. Loren Moriearty says:

    Still use mine every day. It’s seldom been folded shut as it sits open on my desk. No problems whatsoever. Bought it new around 35 years ago.

  12. Michael P. says:

    OMG… I’m so happy to find at least a few other folks out there who know about what I consider to be the best, most efficient hand calculator ever created. I “inherited” mine from an old roommate in my undergraduate years in the mid-80’s — he simply moved on and left it behind one day.

    Everything still works on mine. Indeed, handy quick HEX and octal conversions, quick and dirty STD (both divide-by-n and divide by (n-1) !!), Englishmetric conversions, and even basic physics and EE constants built in(!). And so much more..

    Sure, if I need to do any comprehensive hardcore stats or numerical analysis, I end up coding something in Python or MATLAB (or even Excel), etc. My fancy HP calculators have long since been left at home gathering dust because they are redundant if you’re going to have to make the jump to some coding/plotting or sophisticated spreadsheet building. You’re just going to skip right over your graphing calculator at that point. This is why I maintain that the EC-4013 was the most efficient, sensible, *optimal* hand-held calculator ever created (I’m only a little biased :) :) ).

    And to those asking about the battery — That’s part of the beauty of it: It’s 100% solar powered and never needs any battery replacement !!

    So to the practical end: Mine as well occasionally fails when using the soft pad buttons on the right — I assume everyone eventually encounters the same issue with the internal ribbon cable wires breaking over time.. But hey, this is absolutely fixable, strictly speaking!

    My next comment — and I’m almost afraid to offer because I will almost assuredly be unable to resist:
    **Anyone interested in reviving your old EC-4013’s??** Mine hasn’t gotten nearly far enough to commit it to exploratory surgery, but if anyone’s is dead out there, I’d offer to try whatever I can to revive it !! ANd of course, we’re talking a labor of love here, this would be for free.

    If anyone’s interested, kindly let me know and we’ll arrange to contact each other. By the way, I’m in the Huntsville, AL area.. There are a lot of us crazy OG’s here stuck on our old engineering toys :)

    All best,

  13. Lee says:

    Michael P (and everyone else!), I’m really gratified to hear all the stories about this beautiful nostalgic device! I am increasingly sad that I discarded my EC-4013!

  14. Nate Adams says:

    I bought mine in college, early 80’s. I agree, it was my favorite calculator. Technology is vapor, today’s cutting edge is tomorrow’s obsolescence – but this calculator still rocks at almost 40! It’s been in a drawer for years. Today I got it out and tested it, I’m giving it to my son as he starts college. Everything seems to work fine. Has anyone got a manual? Could I get a pdf scan?

  15. Michael Hendricks says:

    Any have access to the instruction manual. I just found one in a laptop back that I purchased used.

  16. Lee says:

    If anyone can help out Michael with a manual, leave a comment and I’ll forward your email address to him. Don’t leave your address in the comment itself, you might start getting more spam.

  17. Eirual Mac says:

    Did anyone come up with a manual?
    I’ve pulled mine out of a drawer and happy it still works! Trying to hand off to high school son!

  18. Butch says:

    Does anyone have the manual for the EC-4013? Mine is still working and I would like to use the functions again.

  19. David says:

    I bought mine in the 80’s. I got a new job and didn’t need it, so it was relegated to an old desk drawer. I did store it opened so the fold has almost no time on it. Everything works perfectly. However, I too have lost the manual and would like to find a copy if possible. If anyone has a scanned copy of the manual please let me know and I’ll be happy to upload it to “archive . org” in case others need it. thank you.

  20. Carl says:

    The Radio Shack EC-4013 is a rebranded Casio FX-451. Casio made 4 calculators of this particular design. The FX-411 (8-digit), the FX-450 (10-digit), the FX-451 and finally the FX-451M.

    The FX-411 was an 8-digit version of the FX-450 and sold for a little cheaper price than the FX-450.

    The FX-450 (also rebranded as the Radio Shack EC-4011) was 10-digits. Both the FX-411 and the FX-450 were sealed designs so to get to the internals you had to cut into the back fabric of the calculator to get to the 4 screws that hold the internals to the front panel. Both the FX-411 and FX-450 only ran on Solar power, there is no battery inside.

    The FX-451 is an updated version of the FX-450. Added more functions but was basically the same calculator. Also ran only on Solar power, no battery inside. The FX-451 design did allow you open it up to get to the insides. The front panel is snapped into a frame which is permanently attached to the fabric of the calculator. You don’t need to cut the calculator open like the FX-411 and FX-450 design.

    And finally, the FX-451M is a “C-Power” calculator that did use an internal battery (GR927 – 399 Watch Battery, SR927W, AG7, SR57, SR927, S926S) that by this time is almost certainly dead (almost 40 years later). Hopefully it has not leaked. It is replaceable.

    As for a manual for the FX-451 / EC-4013, I found the Casio version on here:

    I did not find the Radio Shack EC-4013 manual but rest assured it is the exact same as the Casio FX-451.

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