Reverse-engineering a tiny 1980s chip that plays Christmas tunes

Back in 1980 when I was working on my Masters in EE, my capstone project was a chip that would play music. The problem was; that back then, the amount of ROM you could fabricate (at least at our facility) was limited to about 1K at best.

I decided to take a music class to learn a little more about music and thought that would help me with my project. The professor would play various classical pieces and lecture about them. Our homework was to go in a listening room and familiarize ourselves with the music. Everything was on vinyl so you would put a record on, listen, take notes etc.

When the first exam came, the professor would take out a record, and place it on a turntable and play a piece and you were supposed to identify it. I was amazed that all the other students seemed to be getting all of them and I was struggling. I went to the professor's office hours and I explained to him my project and what I was working on. He was very intrigued and suggested that I consider Bach especially Fugue's which has a lot of repetition and cycles (good advice I ended up using Bach Toccata Fugue in D minor, which is used a lot in old timey horror movies and I just loved it).

Later, after talking with other students, they showed me their "system" which was crib notes with things written on them like "Blue label with yellow text = Bethoven", things like that. In other words, they were cheating. They were making crib notes about the record labels in the listening room and paying no attention whatsoever to the music.

Since the professor was so nice to me, I decided to tell him about it. He listened to what I said, and he just said "I see", then asked me about my project. He asked if he could come when I presented my project and I was thrilled he was interested.

But he seemed to continue to use the records and the same method, until the final exam when he announced to the class he was going to use a new system, a Tape Deck! You could hear an audible gasp in the classroom. Needless to say, a lot of students did not do so well on the final. I got an A.

I also got an A on my capstone and the EE professors were all very impressed I had taken the time to research the music and my music professor got up and said a few words for me. It was a really cool experience in my life. I hope it is OK that I shared such a long boring story, but every time I see something about a music chip like the kind in greeting cards or whatever, it kind of reminds me a little of my project and how much I enjoyed that experience.

As for the technology of the chip Ken covered, it is of course, quite a bit more sophisticated than mine was, at least as memory serves me (pun intended).

Author here if anyone has questions about the chip...

Behold, the Santasizer courtesy of LMNC (Highly recommended sub, if you like circuit bending, old tech being used to make music, Gameboy/Megadrive arrays etc etc etc)

https://www.youtube.com/watch?v=qcqGqpI4qBU

Merry Christmas!

I had no idea this was a specialised IC that played this tune! I assumed it was a jellybean microcontroller, but thinking about it it makes a lot of sense. These must have been produced in the literal billions over the past few decades.

For what it's worth, I've come across at least three variants of this particular chip that play slightly different versions of the Jingle Bells/Santa Claus is Coming to Town/We Wish You a Merry Christmas tune. In addition to the one in the video, there's one that holds a note for slightly too long during Jingle Bells ("oh what fun it is to ride" becomes "oh what fun it is - -", and another that repeats the first line of "We Wish You A Merry Christmas" a third time.

I wonder if they're knockoffs, and if so how they're constructed!

As a kid I used open up those handheld games beginning 80s to try to figure out how they worked; most has just 1 blob on the pcb which contained the chip and not much more but I did get some good results, like a Pacman clone had 2 blobs; one if them was a music chip which contained 100s of tunes mosty unrelated to Pacman; by figuring out what was the power and what was the signal to select the tunes (there was not much choice and if I remember the correctly the signal was serial). Great fun. Took me a lot of time and the games would be broken afterwards; luckily my parents liked that I was learning stuff instead of playing the actual games.

These chips are everywhere in Shenzhen--usually playing loudly when a gate is opening. It was a bit strange the first time I heard it. Of course, they have no cultural connection to these tunes, so it works fairly well as a warning.

The linear-feedback shift register method is also used for procedurally generating content in e.g. demos. Funny to see this implemented in hardware and it would be interesting to know when this trick was used firstly.

I wonder if someone could get the Apollo source code compiled and running on this chip to finally once and for all prove that old chestnut (i.e. the musical greeting card has more computing power than the Apollo Lunar lander)

It’s hard to imagine, how they designed this chips without having modern wafer design tools. Crazy

> I dissolved the epoxy package in boiling sulfuric acid to expose the silicon die inside

What!!?

Any idea where i can source some of the -01L or 01S versions ( or something similar ). My google fu seems to be rusty… Id like 5-10 for some projects with the kids.