RZ57 Disk Drive Write Faults

This Field Change Order (FCO) RZ57-F001 addresses a firmware issue in RZ57-E disk drives (Rev. C01 and below) when configured with VS4000 Model 60, VLC, and Model 90 systems. The issue involves a bug in the interrupt service routine that can lead to false error recovery or data failing to be written without host notification. The solution is to install a new firmware EPROM (Rev. D01/6000 microcode) provided in the kit. The document includes detailed safety precautions, installation procedures for the SZ12 expansion box, and testing instructions.