Gregory's ServerI think the chip is a 1970s Soviet design, but I'm not sure. The wafer may be from Ukrainian manufacturing scrap. The die has a mysterious symbol that may indicate the manufacturer, but nobody could identify it.
https://twitter.com/kenshirriff/status/1741661696320766233 16/20
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Here's a schematic of the chip from the Motorola datasheet. The four toggle flip-flops (red) count the 4 bits. To count up, toggle if a carry; toggle if a borrow to count down. The blue gates compute carry/borrow if all 1's or 0's below as appropriate, causing a toggle. 18/20 This diagram shows the chip with functional blocks labeled. The four bits are arranged roughly symmetrically. The toggle logic and carry-out logic are squeezed into available space. 19/20  @kenshirriff this reminded me of an old Zachtronics Flash game, "KOHCTPYKTOP: ENGINEER OF THE PEOPLE," which was all about putting together CMOS logic on a layered grid of pixels. I never made it very far in. |
The chip's part number is К561ИЕ11. Soviet ICs have a rational numbering system. 61 indicates a clone of 4000-series CMOS. И is digital, while ИЕ is a counter. So you know from the part number that the chip is a CMOS counter.
https://en.wikipedia.org/wiki/Soviet_integrated_circuit_designation 17/20