7400 competition entry: Lazarus-64

Posted on Friday, September 23rd, 2011 in 7400 contest by Ian

Here’s an entry in the Open 7400 Logic competition: Lazarus-64

I like the idea of a 74x logic competition! Here is my entry, a retro computer that generates all video using ONLY 74hc logic parts…

The latest version even has a 4 voice sound system, including a white noise channel made using a linear shift register.

Currently, the 74HC chip count is well over 100 and I am still reworking the design.


This entry was posted on Friday, September 23rd, 2011 at 12:30 pm and is filed under 7400 contest. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

7 Responses to “7400 competition entry: Lazarus-64”

  1. Ryn says:

    This has to be the 1st prize. I can’t imagine something more complex being posted in this contest.
    Simply amazing.

  2. Michail says:

    Well, I was amazed too. Untill I figured out how many ATMEGA micro’s are used there.
    That’s just a little not fair to not mention that in description.
    What you see on screenshot was not generated by 7400 only.

  3. Ryn says:

    Oh, too bad. But the early designs were pretty nice too (and only used 7400).
    They looked really complex and I thought (maybe it’s just because I’m new to Electronics) seemed more than good enough for this contest.

  4. Michail says:

    @Ryn even the earliest designs had AVR.

  5. Ryn says:

    Oh sorry, I’ve skimmed it and didn’t see the AVR324p ^^ Still not bad tough ^^
    I want to try something similar after my current project, direct VGA output from a microcontroller (or many, interfacing a few ATTINY45?), maybe even rendering sprites/graphics.

  6. Brad Graham says:

    Hey thanks for choosing my Lazarus-64 project!

    The entire video subsystem as well as the sound generator is 100% 7400 logic parts. The AVR is acting like a “cartridge”, hurling out bytes to the dual NTSC video frame buffers, which are made up of mainly 7400 logic and some 32k SRAMS. Lazarus-64 works with any microcontroller, and is all old-school logic at its core.


  7. Brad Graham says:

    Thanks for the positive feedback.

    I have not had much time to update Lazarus to the current status, but the AVR sync generator has been removed and replaced by mainly 7400 logic and a bunch of 688 comparators. The sound system is also mainly 7400 logic and counters.

    I hope to find the time to update the site soon.

    Thanks to DangerousProto for the great site and running this contest. So many amazing projects here.


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