IBM DBCA-204860 Hard Drive Specifications - Page 125

Read Buffer

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12.11 Read Buffer (E4h) Command Block Output Registers Register 76543210 Data Feature Sector Count Sector Number Cylinder Low Cylinder High Device/Head 1 1D Command 11100100 Command Block Input Registers Register 76543210 Data Error ...See Below... Sector Count Sector Number Cylinder Low Cylinder High Device/Head Status ...See Below... Error Register 76543210 CRC UNC 0 IDN 0 ABT T0N AMN 00000V00 Status Register 76543210 BSY RDY DF DSC DRQ COR IDX ERR 0V0 0 V Figure 76. Read Buffer Command (E4h) The Read Buffer command transfers a sector of data from the sector buffer of device to the host. The sector is transferred through the Data Register 16 bits at a time. The sector transferred will be from the same part of the buffer written to by the last Write Buffer command. The contents of the sector may be different if any reads or writes have occurred since the Write Buffer command was issued. Command Descriptions 117

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12.11
Read Buffer
(E4h)
Command Block Output Registers
Command Block Input Registers
Register
76543210
Register
76543210
Data
Data
Feature
Error
...See Below...
Sector Count
Sector Count
Sector Number
Sector Number
Cylinder Low
Cylinder Low
Cylinder High
Cylinder High
Device/Head
1
1D
Device/Head
Command
11100100
Status
...See Below...
Error Register
Status Register
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
CRC UNC
0
IDN
0
ABT T0N AMN
BSY RDY DF
DSC DRQ COR IDX ERR
0
0
0
0
0
V
0
0
0
V
0
0
V
Figure 76. Read Buffer Command (E4h)
The Read Buffer command transfers a sector of data from the sector buffer of device to the host.
The sector is transferred through the Data Register 16 bits at a time.
The sector transferred will be from the same part of the buffer written to by the last Write Buffer command.
The contents of the sector may be different if any reads or writes have occurred since the Write Buffer
command was issued.
Command Descriptions
117