Not sure about this specific example, but here's how cutovers between exchanges were achieved at the time. A similar process was probably used: https://youtu.be

Not sure about this specific example, but here's how cutovers between exchanges were achieved at the time. A similar process was probably used: https://youtu.be/VVTzEVPz1YA https://youtu.be/VVTzEVPz1YA (the actual cut-over procedure starts at 8:20)