Emulex MD21/S2, Техническое руководство

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MD21 Disk Controller Overview
2.2.,2.1 8031 Microprocessor
With the disk formatter, the 8031 microprocessor controls all disk
drive operations. These disk operations include drive control, head
positioning, and reading drive status.
During disk operations, the disk formatter controls formatting of
the data that is written to, and read from, the disk drive. The
8031 microprocessor generates read and write commands that are
executed by the disk formatter. All read and write commands
involve operations only on a single data block (256 or 512 bytes).
2.2.2.2 Disk Formatter
The disk formatter is a 40-pin VLSI IC fabricated with CMOS gate
array technology. This circuit, along with the 8031
microprocessor, handles the read and write operations of the disk
drives.
2.2.2.3 Buffer Controller
The buffer controller is a 68-pin VLSI IC fabricated with CMOS
gate-array technology. The circuit is basically a three-channel
DMA controller. The buffer controller controls data movement in or
out of a dynamic buffer memory and provides the connection between
the microprocessor bus and the data bus.
The buffer controller circuit provides the address and control for
multiple MD21 Controller activities that access a dynamic buffer
memory. The buffer controller performs the following operations:
• Handles buffer addressing and control operations for the
disk formatter
• Handles buffer addressing and control operations for the
SCSI protocol controller
• Handles dynamic memory timing and refresh
• Performs parity checking and generation for the buffer
memory
• Connects the microprocessor bus to the data bus
• Decodes the microprocessor address
for
the buffer memory and
the internal input/output (I/O) space in the MD21 Controller
• Determines priority of buffer memory access
General Description 2-5