Thread by @agirisan

A while ago, I got ahold of the speech board from the arcade game Berzerk. The star of the show is a TSI S14001A speech chip. And it lives, kinda!

CHICKEN, FIGHT LIKE A ROBOT

Berzerk is notable for being one of the earliest arcade games with speech, and the S14001A is itself one of the first (perhaps the first?) single-chip speech synthesizers, from the mid-70s. This page has a nice overview: vintagecalculators.com/html/developme…

The Stern VSU-1000 is a pretty cool board. The game program has software control over the speech pitch and volume, and the speech ROMs and timing/interface circuitry are all on-board, so you can do a simple write to tell it to start talking, and away it goes.

Unfortunately, there's a slight problem. You may have noticed some audio glitches in the video. That is because my S14001A is faulty :(

The problem seems to be that one of the address lines to the EPROMs has very weak drive. Here I lifted the pin and ran it through a cliplead, and you can see just bringing my hand near it is enough to make it glitch out...

Even an oscilloscope probe causes problems. I'll spare you the scope traces, they're pretty tragic.

The cause? Not sure. It could be ESD damage -- I was careful with it, but the previous owners may not have been. I also noticed that the IC package is actually slightly bent (!!!) so perhaps a fractured bond wire?

It seems to work fine for a minute or two, and then it'll be completely messed up for a while. It's also possible it was faulty from the factory, or has some age-related fault that developed over time.

Of course it's the one part on the board that isn't something I can replace off-the-shelf. There are a few sources for the chips, but they all cost more than I paid for the board...

Maybe I can place a buffer close to the pin and drive the EPROMs from that. It would help reduce the load on that output. Further experimentation is required, but that's for another time.

If you're into old speech synth tech, I've played a few other chips. First is the General Instrument SP0256-AL2, which we had answering the phone here for a while

Another is the Texas Instruments TMS5220. An earlier LPC chip from TI, the TMC0281, is famous for being the voice of the Speak and Spell. This old tweet has a video

https://twitter.com/agirisan/status/1232570466910527494

All of the chips mentioned so far basically implement very efficient encoding schemes optimized for human speech. The voices in Berzerk and the Speak and Spell devices, while using different algorithms, were encoded from real speech.

The SP0256-AL2 is slightly different in that you can feed it allophones, which form speech when concatenated. It's actually an LPC chip similar to the TI ones, but has allophone LPC data in internal ROM, so you don't need to encode anything yourself.

One chip that works a bit differently is the Votrax SC-01/SC-01-A, probably most well-known for being the voice of Qbert.

I actually have a later version of that chip, the SSI-263 (aka Votrax SC-02) sitting around. Let me know if you'd like to hear that one up and running~