Russian kempston mouse with wheel support

This is common Kempston mouse. The only difference is in the additional counters at the D4-D7 on buttons port  Counter is 4-bit and its value increases with the movement of wheels down, decrases the movement up.

Buttons port:
D0: right button
D1: left button
D2: middle button
D3: always log.1
D4: bit 0 of wheel counter
D5: bit 1 of wheel counter
D6: bit 2 of wheel counter
D7: bit 3 of wheel counter

So far, there is a single emulator with the support of wheel mouse. Its name is ZX-EMUL and can be downloaded for example

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