How does the Windows 98 PC control the lathe?
How is it connected to the lathe?
What commands does it send to the lathe? Does it use GCode?
If there is a serial interface with the lathe it should be possible to link up with an Arduino. However if it is only a USB connection a Raspberry Pi might be a better option.
The machine connected to lathe by serial interface and it uses mainly Gcode. Mostly the Emco use sinumerik as a contorl keyboard ,this sinumarik has its proper card wich use RS422.
The maccine has two stepper motor BERGER LAHR MOTOR 564 it'meas 5 phases motor.
This sinumerik is able to control an automatic tool turret .