Designing a basic digital calculator with specific function. 2

[Teslathunder2]

1. “ON/OFF” switch to enable and reset the calculation.
2. “CLEAR” push button to clear/reset the calculation.
3. Push buttons of input Octal numbers 0-6.
4. “ADD(+)” and “EQUAL(=)” push buttons to perform addition for two input octal number such as 168+268=448.
5. “DEL” push button to delete the second number being pressed so that user can re-enter a new number for addition. For example, 18+28press DELpress 68 18+68.
6. Whenever an input octal number is pressed, it will be shown on two 7-segment displays. The results of the “ADD(+)” of two numbers will be shown after “EQUAL(=)” button is pressed. All the adding operation must be done using the same set of display. The maximum number of equal results is 778.
7. “DEC/OCT” switch for user to select the result mode either to show the result in decimal or Octal format on the same display.
8. Instead of using AND, OR, and NOT gates your design, implement your design using ONLY NAND gate for combinational circuit design or sequential circuit design. If the circuit you need can be taken from the library then this requirement is not applied

 

[handleman]

We don't do your homework for you. Just posting your project requirements will not get you anywhere. We may help if you have specific questions. What have you done so far? Where are you stuck?

 

[IRstuff]

Oh, that's interesting; your instructor apparently doesn't care for you to be able to enter the number "7" which is a valid octal number. Kind of makes the calculator a bit of a bugaboo

Oh, also interesting that "8" is a valid octal number, NOT!!!

Seemingly, the calculator can't do octal math very well, either


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[Teslathunder2]

Ah, im sorry , there is an error in point 3, is 0-7. I need help with point 7. I do not know what component to use to change octal number system to decimal system.

 

[MacGyverS2000]

It would seem a form of truth table showing how each octal value translates to a decimal value would be of use here, which can be translated into simple logic gates... breaking down problems into simple steps like that is quite useful for such tasks.

It's only by reading step 8 that we can assume the assignment was to make such a calculator using AND, OR, and NOT gates in the first place... a useful tidbit of info that would have been useful in the beginning.

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