Install DiagRom 1.2
Insert any disk
Select "Drive tests"
Hit 2 to turn on motor
SAE:

vAmiga: 馃き

False alarm. What we see here is a configuration issue. The RDY bit is used to transmit the drive identification code when the motor is off. SAE transmits a 0 because it emulates the internal drive as having a drive ID. Most old Amigas (such as the A500) use internal drives that don't transmit a drive ID (meaning that RDY stays 1 which is displayed as NO). If SAE is configured explicitly to emulate an A500, the output matches what can be seen in vAmiga.

Most helpful comment
False alarm. What we see here is a configuration issue. The RDY bit is used to transmit the drive identification code when the motor is off. SAE transmits a 0 because it emulates the internal drive as having a drive ID. Most old Amigas (such as the A500) use internal drives that don't transmit a drive ID (meaning that RDY stays 1 which is displayed as NO). If SAE is configured explicitly to emulate an A500, the output matches what can be seen in vAmiga.