The first parts that I purchased for my computer included two breadboards and the logic chips to build a simple Arithmetic Logic Unit that could preform addition and subtraction on 4 bits. Initially I was going to build a 4 bit computer, but I later decided that having a computer that could only operate with integers from 0 to 15 would be rather boring. I learned something very important with my first purchase: NTE chips are not meant for projects. NTE chips are fairly common if you are searching for cheap parts, and the reason behind that is that they are replacements for the real thing. I constructed my 4 bit full-adder and only got accurate output %20 of the time. The rest of the time the output remained erroneous.

The First Parts

My dysfunctional ALU


9 Responses to First Parts

  1. Graham Braly says:

    Can you use NTE chips at all? My local fry’s stocks pretty much every 7400 and 4000-series chips there are but the are all NTE. However I found my NTE 74HC02 is just a re-branded TI 74HC02 with the original markings painted over.

    • Kyle says:

      Go ahead and try using them. There is a good chance that during the first run of my ALU for the first computer I was going to build (4-bit) that I may have fried the chips. There is also a chance that they were defective to begin with though as some chips that I did not use initially still had problems. I got my batch from a Fry’s as well. My suggestion would be to try a few parts just to test the water, NTE parts are meant for replacement but should function just like standard chips.

  2. KAKA says:

    Can you post most, if possible, all the list of parts you used? Posting on instructables would be good.

  3. Mekhal says:

    God job man ^^

  4. Housefull 2 says:

    Very nice blog great info nice!

  5. Cody says:

    How many resisters will I need to buy and where do I put them?

  6. Cody says:

    Where did buy your SPDT switches from? The ones that found where too expensive.

    • Kyle says:

      I got mine from Jameco, they are a bit pricy if you buy a lot of them. Ebay might have some bulk supply if you find the right seller, just make sure you don’t order cheap parts that are actually cheap.

Leave a Reply

Your email address will not be published. Required fields are marked *