The release of the 2.7 hardware contained only minor changes, and the addition of a part - GT20SL16S1Y. This is labelled on the schematic as U20.
After scouring the internet for hours with various combinations of the part number, I have been anable to find any reference to a device that even remotely fits the description. In fact, the existance of six pin serial memory devices is quite uncommon - most are 8 pin.
The best I could find was from a Russian forum, where the writer of the post claimed it was for “font”. A google translation error?
I eventually decided to crack my DSO open and see if there was a typo in the part number… and much to my surprise, there is no U20! That is, there is a place for it on the PCB, but no part fitted.
My personal best guess it was a pre-specified part that never made it into production. The DSO203 v2.7 was designed for it, but it was left off because it didn’t physically exist.
If any of the designers read this, could they please clarify what U20 is, and what it was meant to be used for?