Audio Digital Delay with DRAM and Arduino

Aka “ADDDA” or “AuDiDeDrAr” or “aww dee dee drawer” or “A3DA”

I’ve had this idea bouncing around in my head that you could use 1-bit wide DRAM as a delay line if you simply counted up through it’s addresses, reading and writing as you go. 1-bit wide DRAM like the M3764 have separate pins for Data In and Data Out which makes the read-and-write method easier.

The light bulb moment was coming across an old post on where one commenter provides a short snippet of code to do a Delta-Sigma analog to digital converter using the Arduino’s analog comparator pins. I had planned to do this purely in software by using the normal ADC pins and then calculating the Delta myself. But the built-in comparator makes this dead simple!

You can just see the OKI DRAM chip under all those wires.
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