Soviet graphic tablet "sketch"

I could not find any information on it. Appearance:



The name "Sketch", there are no signs of use in the form of scratches, but there is a trace from the wire. Back panel:



A pen was connected with a wire.

The nameplate on the back reads "ESK-SB1." Serial number 009.



Remove the cover. The massive plastic case turned out to be milled and painted with plexiglass! That is, this tablet is from an experimental batch! It is clearly made at the factory.





Panel appearance:



Marking with the year of manufacture:



Boards are covered with covers:


Let's look under them:



On the right side there are 8 bits of a microcomputer without ROM KR1816BE35, 2 pieces 573RF2, serial interface KR580vv51a.

The panel is glued into a sandwich, in an oblique light you can see the matrix of electrodes:



For comparison, in size - next to modern tablets: