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Fujitsu MHT2030AT Manual/User Guide - Page 232

Read-ahead Cache, 6.4.1 DATA buffer structure

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Operations 6.4 Read-ahead Cache Read-ahead Cache is the function for automatically reading data blocks upon completion of the read command in order to read data from disk media and save data block on a data buffer. If a subsequent command requests reading of the read-ahead data, data on the data buffer can be transferred without accessing the disk media. As the result, faster data access becomes possible for the host. 6.4.1 DATA buffer structure This device contains a data buffer. This buffer is divided into two areas: one area is used for MPU work, and the other is used as a read cache for another command. (See Figure 6.7) a) 2MB buffer For MPU work 288 KB (294912 bytes) b) 8MB buffer 2048 KB (2097152 bytes) For R/W command 1760 KB (1802240 bytes) For MPU work 288 KB (294912 bytes) 8192 KB (8388608 bytes) For R/W command 7904 KB (8093696 bytes) Figure 6.7 Data buffer structure The read-ahead operation is done by the following commands. • READ SECTOR (s) (EXT) • READ MULTIPLE (EXT) • READ DMA (EXT) • READ DMA QUEUED (EXT) • READ STREAM PIO • READ STREAM DMA 6-12 C141-E192-02EN

Section	Page
Front Cover	1
FOR SAFE OPERATION	2
Revision History	3
Preface	5
Important Alert Items	9
Manual Organization	11
Contents	13
Illustrations	18
Figures	18
Tables	20
CHAPTER 1 Device Overview	21
1.1 Features	22
1.1.1 Functions and performance	22
1.1.2 Adaptability	22
1.1.3 Interface	23
1.2 Device Specifications	24
1.2.1 Specifications summary	24
1.2.2 Model and product number	25
1.3 Power Requirements	26
1.4 Environmental Specifications	28
1.5 Acoustic Noise	29
1.6 Shock and Vibration	29
1.7 Reliability	30
1.8 Error Rate	31
1.9 Media Defects	31
1.10 Load/Unload Function	31
1.11 Advanced Power Management	32
CHAPTER 2 Device Configuration	35
2.1 Device Configuration	36
2.2 System Configuration	37
2.2.1 ATA interface	37
2.2.2 1 drive connection	37
2.2.3 2 drives connection	38
CHAPTER 3 Installation Conditions	39
3.1 Dimensions	40
3.2 Mounting	41
3.3 Cable Connections	47
3.3.1 Device connector	47
3.3.2 Cable connector specifications	48
3.3.3 Device connection	48
3.3.4 Power supply connector (CN1)	49
3.4 Jumper Settings	49
3.4.1 Location of setting jumpers	49
3.4.2 Factory default setting	50
3.4.3 Master drive-slave drive setting	50
3.4.4 CSEL setting	51
3.4.5 Power Up in Standby setting	52
CHAPTER 4 Theory of Device Operation	53
4.1 Outline	54
4.2 Subassemblies	54
4.2.1 Disk	54
4.2.2 Spindle	54
4.2.3 Actuator	54
4.2.4 Air filter	55
4.3 Circuit Configuration	55
4.4 Power-on Sequence	58
4.5 Self-calibration	59
4.5.1 Self-calibration contents	59
4.5.2 Execution timing of self-calibration	60
4.5.3 Command processing during self-calibration	61
4.6 Read/write Circuit	61
4.6.1 Read/write preamplifier (PreAMP)	61
4.6.2 Write circuit	61
4.6.3 Read circuit	63
4.6.4 Digital PLL circuit	64
4.7 Servo Control	65
4.7.1 Servo control circuit	65
4.7.2 Data-surface servo format	68
4.7.3 Servo frame format	70
4.7.4 Actuator motor control	71
4.7.5 Spindle motor control	72
CHAPTER 5 Interface	75
5.1 Physical Interface	76
5.1.1 Interface signals	76
5.1.2 Signal assignment on the connector	77
5.2 Logical Interface	80
5.2.1 I/O registers	81
5.2.2 Command block registers	82
5.2.3 Control block registers	87
5.3 Host Commands	88
5.3.1 Command code and parameters	88
5.3.2 Command descriptions	92
5.3.3 Error posting	182
5.4 Command Protocol	184
5.4.1 PIO Data transferring commands from device to host	184
5.4.2 PIO Data transferring commands from host to device	187
5.4.3 Commands without data transfer	188
5.4.4 Other commands	190
5.4.5 DMA data transfer commands	190
5.5 Ultra DMA Feature Set	192
5.5.1 Overview	192
5.5.2 Phases of operation	193
5.5.3 Ultra DMA data in commands	193
5.5.4 Ultra DMA data out commands	198
5.5.5 Ultra DMA CRC rules	202
5.5.6 Series termination required for Ultra DMA	203
5.6 Timing	204
5.6.1 PIO data transfer	204
5.6.2 Multiword data transfer	205
5.6.3 Ultra DMA data transfer	206
5.6.4 Power-on and reset	219
CHAPTER 6 Operations	221
6.1 Device Response to the Reset	222
6.1.1 Response to power-on	222
6.1.2 Response to hardware reset	223
6.1.3 Response to software reset	225
6.1.4 Response to diagnostic command	226
6.2 Power Save	227
6.2.1 Power save mode	227
6.2.2 Power commands	229
6.3 Defect Processing	229
6.3.1 Spare area	229
6.3.2 Alternating processing for defective sectors	230
6.4 Read-ahead Cache	232
6.4.1 DATA buffer structure	232
6.4.2 Caching operation	233
6.4.3 Using the read segment buffer	235
6.5 Write Cache	239
6.5.1 Cache operation	239
Glossary	243
Acronyms and Abbreviations	247
Index	249
Comment Form	251