HP Calculators Timeline » HP 18c Business Consultant.

HP 18c Business Consultant.

The HP 18c was the first in a series of "clamshell" calculators produced by HP. The HP 18c opens like a book with two keyboards facing each other inside. The HP 18c included graphing and a date-time-alarm feature similar to a personal organizer. The 18C had 2K of memory and it used algebraic logic with parentheses (but no precedence) and the multi-line display.

1986 - 1988

Updated On: 12.07.10

  1. On 17-Nov-2019, Anonymous wrote: 
    L'apparecchio è stato fermo 4-5 anni, ora non si accende più. Cosa posso fare per risolvere? Grazie
    Your reply to Anonymous

  2. On 15-Nov-2017, Rink wrote: 
    I mistakenly put wrong batteries in my old HP-18c. Now it doesn't work. Can it be fixed?
    Your reply to Rink
    • On 17-Nov-2017, Ron replied: 
      I have heard of one individual who did the same, then replaced the batteries with the correct ones and it worked.
      However, I suspect he was extremely lucky. This particular calculator design is nearly impossible to fix.
      It is still valuable and can easily be sold. Why? The battery door is valuable to other Hp 18c, 19b or 28c/s calculator users.
      Your reply to Ron

  3. On 09-Apr-2013, Mike wrote: 
    Trying to find battery type and No. for HP 18c Business Consultant. Can anyone help? Thanks
    Your reply to Mike
    • On 09-Apr-2013, Ron Ross replied: 
      The Hp 18C (and 19B, Bii, 28c and 28s) all use N cell batteries. These are 1.5 Volt and NOT 12V like some garage door controllers use that are very nearly the same size and dimensions. Of course if you use the 12 Volt batteries (and more people have done so than I care to count), you put 36 Volts where only 4.5 volts is designed and you (not you, but others) ruin the fine vintage calculator. Remember N cell, often called instrument batteries. Usually these batteries are on the costly side of $5 per pair and are sold in pairs. You only need three, so the fourth is often put away, never to be seen again.
      Your reply to Ron Ross
      • On 17-Aug-2017, Anonymous replied: 
        i understand i need 3 times 1.5v batteries , is it enough or do you have name far that example Duracell and so on (Reply)
      • On 17-Aug-2017, Anonymous replied: 
        i understand i need 3 times 1.5v batteries , is it enough or do you have name four that : example Duracell and so on (Reply)
      • On 27-Oct-2017, Anonymous replied: 
        seriously? (Reply)

  4. On 31-Oct-2012, Dennis wrote: 
    Re: HP-18c Machine reset
    I want to use this for an upcoming test because of its date and statistical functions, but whenever I press the ’sum’ key I get "machine reset". All other keys and functions seem to be ok. It has passed both the general self-test and the keyboard test. Any thoughts appreciated. Thanks.
    Your reply to Dennis
    • On 08-Nov-2012, Anonymous replied: 
      Change all three N batteries
      Your reply to Anonymous
    • On 08-Nov-2012, Anonymous replied: 
      The problem was I ran out of memory - 12K will take you only so far. Did a memory purge and all is working as it should.
      Your reply to Anonymous
      • On 09-Jul-2015, Anonymous replied: 
        How exactly do you perform a memory purge? (Reply)
      • On 10-Jul-2015, Ron replied: 
        There are a couple of ways to clear your 2 K of RAM. (that's right, 2 K not 12 K on the 18C). An Hp 19B has 8 K of RAM, looks the same. A down and dirty way is simply remove the batteries and turn on (of course it won't turn on, but that will clear out all memory and perform a calculator reset). However, a cleaner way is to enter the solver menu or summation menu and delete the equations or the named lists. That will free up your memory. or you can use the yellow key and then the enter key (above the enter key is Clear All). (Reply)

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In reply to Anonymous, who on 08-Nov-2012 wrote:
Change all three N batteries