Interface - Fujitsu MCJ3230SS Product Manual

1.1.5 Interface

(1) Conformance to SCSI-2
This optical disk device supports the basic functions of SCSI-2.
SCSI commands enable data manipulation using logical block addresses that are
independent of the physical attributes of the optical disk device, enabling software
flexibility in terms of system expansion in the future.
(2) Continuous block processing
Logical block addresses are used for data block addressing. Without consideration
of the physical attributes of track boundaries, the host can access data by
specifying a block number in logically continuous data space.
(3) Data buffer
7,600 KB buffer is used to transfer data between the SCSI bus and disk. Since
data is stored in this buffer, the host can execute input-output processing
effectively by using the high-speed data transfer capability of the SCSI bus
without regard to the data transfer rate of the optical disk drive.
(4) Read-ahead cache feature
The read-ahead cache feature enables high-speed sequential data access as
follows:
After executing a command to read data from the disk, the drive automatically
reads the next data block and stores it in the data buffer (pre-reading). If the next
command requests this data, the data is transferred from the buffer without another
disk access.
(5) Write cache feature
When the host system issues the write command to the optical disk drive, a
command complete is usually responded after completion of the write and verify
operations. By using the write cache feature, a command complete is responded
after completion of the data transfer to the data buffer without waiting the
completion of the write and verify operations then the write and verify operations
are made asynchronously with the interface operation. Therefore, the apparent
write command processing time measured at the host system is reduced and the
I/O performance of the host system is improved.
The write cache feature is enabled or disabled by MODE SELECT command.
C156-E224-01EN
1.1 Features
1-5