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The decoder

2011
19
September

This was a simple project I finished a while ago, but never wrote anything about.

The lack of this device was discovered while debugging my 6502 computer (which I will cover later). I needed to debug the address bus while stepping through a simple program in ROM. Due to the lack of a advanced oscilloscope, I wanted a solid device I could hook up to anything with a 16 bits wide bus or less.

16-bit address decoder

This is the final layout. The address bus is segmented in 4 bits, each passing through a MC14495, which happens to be a CMOS 4-bit parallel to 7-segment driver. All I did was to connect the dots and add a few rails for the power, and etch the bugger.

Yes, it is a simple device, but it has proved to be extremely functional and useful.


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2 Comments

  • hi, what country are you from? Such golden MC14495 ic is not available in my country. damn! Also, as far as I know, motorola stopped manufacturing the hex to 7segment driver decades ago.

    -glenn

  • Hi Glenn. I bought the MC14495 lot on eBay a while back, and they are great to work with. It's a real shame they are obsolete now, because my stock is running low. When the digits 0-9 are required, I'm using 74LS47 instead.

    #556 | Comment by admin on Jan 3, 2013 08:59am

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