Specifications
      Show Part Numbers

Feature Description
Manufacturer Western Digital
Manufacturer model WD400BB
Formatted capacity 40,020 MB
Interface 40-pin EIDE
Actuator type Rotary Voice Coil
Number of Disks 1
Data Surfaces 2
Number of Heads 2
Bytes per sector 512
User sector per drive 78,165,360
Servo Type Embedded
Recording Method EPR4 Rate 16/17 PRML
ECC Reed Solomon
Head Park Automatic
Average Seek (read) 8.9 ms average
Average Seek (write) 10.9 ms average
Track to Track Seek 2.0 ms average, 5 ms maximum
Full Stroke Seek 21 ms average
Index Pulse Period 8.3 ms (nominal)
Average Latency 4.2 ms (nominal)
Rotational Speed 7200 RPM (nominal)
Data Transfer Rate (Buffer to Host) 100 MB/s (Mode 5 Ultra ATA)
66.6 MB/s (Mode 4 Ultra ATA)
33.3 MB/s(Mode 2 Ultra ATA)
16.6 MB/s (Mode 4 PIO)
16.6 MB/s (Mode 2 multi-word DMA)
Transfer Rate (Buffer to Disk) 525 Mbits/s maximum
Interleave 1:1
Buffer Size 2 MB
Spindle Start Time
From Power-on to Drive Ready		 7.0s average, 9.0s maximum
Spindle Start Time
From Power-on to Rotational Speed		 5.0s average, 7.0s maximum
Spindle Stop Time 6.5s average
Contact Start/Stop Cycles (CSS) 50,000 minimum