Fujitsu MHL2300AT, MHM200AT manual Read/write Circuit, Command processing during self-calibration

Theory of Device Operation

Table 4.1 Self-calibration execution timechart

	Time elapsed	Time elapsed
		(accumulated)
1	At power-on	Initial calibration
2	About 5 minutes	About 5 minutes
3	About 5 minutes	About 10 minutes
4	About 10 minutes	About 20 minutes
5	About 10 minutes	About 30 minutes
6	About 15 minutes	About 45 minutes
7	About 15 minutes	About 60 minutes
8
.
.	Every about 30
.	minutes
.

4.5.3 Command processing during self-calibration

If the disk drive receives a command execution request from the host while executing self-calibration according to the timechart, the disk drive terminates self-calibration and starts executing the command precedingly. In other words, if a disk read or write service is necessary, the disk drive positions the head to the track requested by the host, reads or writes data, and restarts calibration.

This enables the host to execute the command without waiting for a long time, even when the disk drive is performing self-calibration. The command execution wait time is about maximum 40 ms.

4.6 Read/write Circuit

The read/write circuit consists of the read/write preamplifier (HDIC), the write circuit, the read circuit, and the time base generator in the read channel (RDC). Figure 4.4 is a block diagram of the read/write circuit.

4.6.1 Read/write preamplifier (HDIC)

HDIC equips a read preamplifier and a write current switch, that sets the bias current to the MR device and the current in writing. Each channel is connected to each data head, and HDIC switches channel by serial I/O. HDIC generates a write unsafe signal (WUS) when a write error occurs due to head short-circuits or head disconnection, that avoids error writing.

4-10 C141-E104-02EN