LSI Symbios SYM53C040, Technical Manual

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2-4 Functional Description
2.1.4 SFF-8067 Interface
The two SFF-8067 interfaces allow the SYM53C040 to communicate with
Fibre Channel SCA-2 devices to transfer SES information to/from Fibre
Channel host controllers. The information is transferred across the signal
pins used to provide the loop identifier to the SCSI device. Details of the
protocol are provided in the SFF-8067 draft specification.
2.1.5 16 Kbytes SRAM
The SYM53C040 contains 16 Kbytes of internal static RAM for data and
firmware storage. Under microcontroller control, the internal RAM may be
loaded with additional firmware from an external parallel ROM, or
automatically from a serial EEPROM using the Two-Wire Serial interface.
Note: The external parallel ROM must not be mapped into the
first 16 Kbytes or the last 1 Kbyte of the external memory.
2.1.6 DMA Function
The DMA block provides memory access from and to the SCSI core.
During DMA operations, the microcontroller is put in an idle state and the
internal bus is driven by the DMA block. External memory access by the
DMA block happens in the same way that microcontroller memory
accesses occur. Control of the DMA block is achieved through a set of
control registers shown on the memory map in
Figure 2.2 and is
described in Chapter 4 .
2.2 Memory Map
All memory accesses are visible on the external microcontroller memory
bus.
Figure 2.2 is the memory map of the SYM53C040.
Note: It is the responsibility of the system designer to prevent
other external devices from conflicting with internal memory
options.