IBM 0663 Series Manual page 3

Figure 1 Option Block
With the auto start jumper in place the motor spins up when power is applied. With the auto start
jumper removed the motor spins up when the drive is issued a Start Unit command.
Note:
During the power up sequence the option pin is interrogated. If it is grounded the pin remains an
input. If it is not grounded it becomes an output, indicating Motor Active or Command Active
depending on the state of the CMDAC bit in Mode page 0.
As an input the option pin has several effects upon the SCSI function. Please refer to the 0661
SCSI Specification for details.
MODE SELECT OPTIONS
Certain 'Mode Select' parameters are alterable via the SCSI 'Mode Select' command. This allows
certain drive characteristics to be modified to optimize performance on a particular system. Refer
to the 0663 Disk Drive SCSI Specification for detailed definition of Mode Select parameters.
Changeable parameters are:
Block Descriptor
Number of Blocks
Block length
Page 0
QPE (Qualify Post Error)
UQE (Untagged Queueing Enable)
DWD (Disable Write Disconnect)
ASDPE (Additional Save Data Pointer Enable)
CMDAC
RPFAE (Report Predictive Failure Analysis Error)
CPE (Concurrent Processing Enable)
Page 1
AWRE (Automatic Write Reallocation Enable)
ARRE (Automatic Read Reallocation Enable)
TB (Transfer Block)
RC (Read Continuous)
PER (Post Error)
DTE (Disable Transfer on Error)
DCR (Disable Correction)
Read Retry Count
Page 2
Read Buffer Full Ratio
Write Buffer Empty Ratio
Maximum Burst Size
Page 7
PER
DCR