Steamed Hams Localized Entirely Within A Printed Circuit Board

Maybe you’ve heard of a TV show called The Simpsons. Steamed Hams make a one-gag appearance in an unforgettable luncheon where Principal Skinner poker-faces his way out of a disaster with Superintendent Chalmers. Meanwhile, over on imgur, [Agumander] has put a black and white screencap from Steamed Hams in a printed circuit board.

The memory for this chip is an AT28C64, a 64 kilobit or 8 kilobyte steamed RAM. You call it a steamed RAM despite the fact that it is obviously a ROM. There is no microcontroller on this board or really anything resembling programmable logic. Everything is just logic chips. This board displays a 256×256 1 bit per pixel image over composite video. The sync is generated with the help of a 14MHz crystal and some circuitry taken from the original PONG board. Other than that, it’s just a bunch of NANDs and ORs that roll through the address space of the ROM and spit values out over a composite video port.

The build began by breadboarding everything save for a nifty solderless breadboard power adapter. Three ROM chips were programmed with different images — a cat, something to do with vaporwave, and some guy that looks like the poster from Eraserhead. Everything worked on the breadboard — yes, even at 14 MHz — so the build moved on to a printed circuit board.

The result is fantastic, and should work well on anything with a composite video port. We’re awarding bonus points for putting a socket on the ROM, simply so [Agumander] can change the image without whipping out the desoldering braid. If you need a refresher on Steamed Hams, it’s from the 7th season Simpsons episode ’22 Short Films About Springfield’.

23 thoughts on “Steamed Hams Localized Entirely Within A Printed Circuit Board

    1. Yes if you are not a Simpsons watcher the essence of the article is pretty well hidden among lots of obscure-sounding Simpsons noise. pelrun’s precis would have been a far better title than some blurb about steamed ham. The point of the project is the circuit, not The Simpsons.

        1. No, the OP is right and IMHO its’ mostly down to this line

          “has put a black and white screencap from Steamed Hams in a printed circuit board. ”

          Put it in the PCB?
          Eteched it on?
          Sandwiched it in one of multiple layers in copper?
          Drew it in pen?

          Ah, you mean built a circuit on a PCB to output it over composite to a monitor.
          Even tho the pic looks like an Etch A Sketch.
          But not till end of 2nd paragraph is that remotely clear.

          And the steamed hams reference. So it’s a meme.
          Which what, 20% of the readership may even know about “being a thing” as 80% have lives beyond memes.

          But feel free to be obtuse Elliot.


          1. As a non native English speaker I’m in the 20% group. “steamed hams” painted a picture in my head of a group radio amateurs in a steam room. And then some story about an animated sitcom… huh? What’s this all about?

          2. It’s actually both stored in the ROM and also silkscreened on the bottom of the board.

            Apologies for the etch-a-sketch quality. I picked up digital circuit design as a hobby last August so I’m still new at this! :P

  1. that’s actually an EEPROM, clever, when i did the same thing 25 years ago I used an EPROM and still remember the 20 minute erase cycle between tries to correctly align the data.

    Regarding comments about the Simpsons, they are needed because without them there isn’t much else to the project.

    1. Bypass caps are highly overrated.

      I once had to redesign a 3″ circular PCB to fit on a 1″ square PCB. The MCU itself was a 128-pin QFP and took up most of one side of the PCB. Running out of ideas, I took the 3″ prototype and desoldered all of the decoupling caps. It worked. I ran it through standard testing to make sure it held spec, and it did. It even kept up 100-base T Ethernet communication between -80F and +170F.

      If your power regulation is good, and your circuit design is good (aside from no bypass caps), and the whole thing is shielded, bypass caps aren’t critical.

    1. Part of why I didn’t incorporate that functionality into the ROM is that I eventually want to replace it with a RAM chip of the same size, and use it as the video board in a 6502-based game console. Additionally I’m mulling the idea of multiplexing *two* RAM chips to create a double-buffer in hardware.

  2. Woah, I’m famous! The Eraserhead-looking guy is actually me, lol. If you liked that I socketed the ROM, you’ll love the cartridge port I added on the second version of this board.

    1. Principal Skinner was trying to gloss over having ruined dinner by burning it and then secretly buying fast-food at Krusty Burger, poorly disguising the hamburgers by dubbing them ‘steamed hams.’

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