Mouse Expert - Kolobok Bus Mouse

Expert knowledge for the ES-1841's bus mouse.

Key Specifications

| Property | Value | | --------- | ---------------------- | | Type | Bus mouse (not serial) | | I/O Ports | 23Ch-23Fh | | IRQ | 2, 3, 4, or 5 | | Protocol | MS Bus Mouse or InPort |

I/O Ports

| Port | Function | | ------ | ------------ | | 23Ch | Data port | | 23Dh | Signature | | 23Eh | Control port |

Microsoft Bus Mouse Protocol

Control Port:

• Bits 0-1: Counter select
• Bit 2: IRQ enable

Reading (4 reads for X/Y):

Select X-low  → Read nibble
Select X-high → Read nibble → Combine
Select Y-low  → Read nibble
Select Y-high → Read nibble → Combine

InPort Protocol (Alternative)

Indexed access:

• Write index to 23Ch
• Read/write data at 23Dh

| Index | Register | | ----- | ---------- | | 0 | Status | | 1 | X movement | | 2 | Y movement | | 7 | Mode |

Status (Index 0):

• Bit 0: Left button (0=down)
• Bit 1: Middle button
• Bit 2: Right button
• Bit 6: Movement flag

Implementation Notes

Limited ES-1841 documentation exists:

• Try MS Bus Mouse first
• Check MAME ec1841 for reference

References

See references/ for detailed documentation.