It’s technically true that any piece of software can be reproduced in hardware, although modern software’s size and complexity generally makes this a non-starter. But if we go far enough back in time, older software becomes easier and easier to implement in hardware. The original DOOM from 1993 might one day be recreated in full this way, but that day is not today. Instead, [Nick] has recreated the original music from that game, playing the opening track in nothing but 555 timers.
The circuit starts with a 555 timer that acts as a system clock with a rate of just over 7 Hz. These pulses feed a binary counter which in turn feeds a decoder, giving the circuit 15 positions. Each output of the decoder feeds to a diode matrix which stores information about what pitch the circuit should play. The circuit only needs to play six pitches so the diodes effectively connect each moment in time to one of these six notes. From there the circuit feeds into a set of switches which select different resistor networks of another 555 which is actually responsible for producing sound. The resistor networks have different values to adjust the timing of the 555 to produce different pitches.
Of course this entire exercise is largely academic as almost any microcontroller would be able to be programmed to play this chiptune quite easily, but it’s not a bad idea to get down into the weeds of digital logic from time to time in order to refine one’s skills and knowledge about what’s really going on in the inner workings of circuits. Or, go even deeper than that and build the logic gates themselves from first principles.
And it still sounds better than the version of this song in the Sega 32X port…
Doom has already been run on an FPGA, so it has been run in hardware. There’s nothing stopping someone from creating a Doom ASIC except for the cost.
Yeah but programming an FPGA isn’t any fun
Oh I wouldn’t say that.
I work with both, and you are equally right. 😎
https://hackaday.com/2020/05/13/the-doom-chip/ seems pretty fun to me…
https://hackaday.com/2020/05/13/the-doom-chip/
This sure puts the “could have used arduino” crowd to shame.
Imagine this in Miata : ]
Like in a Mazda Miata?
What is impressive, old school form factor and the task of envisioning a composition mathematically and translating that to a circuit. I love audio programming and Doom!
The title is disappointingly clickbaity. I looked at it and thought how can this be? That sounds impossible. And then I clicked on the article.
Extend that counter and send the diode array logic to the traces of a keyboard instead of a 555 and it’ll be able to play a game of doom instead of just the music.
Wrong title. It’s not Doom, but Doom’s music.
More specific E1M1.
Now, replace the 555s with Hammond style tone wheels……..
Click bait. If the title was accurate, I wouldn’t even have looked at this.
From the description, it sounds similar to a circuit I designed with 2 555 timers and a 4017 counter but it can only play 9 notes.
Great project. Now let’s see the opening song of StarWars hard coded in 555 timers.