LSI 53C875A - Manual (Page 133)

SCSI Registers 4-41
•
During a Transfer Control instruction, the Compare
Data (bit 18) and Compare Phase (bit 17) bits are set
in the
DMA Byte Counter (DBC) register while the
LSI53C875A is in target mode.
•
During a Transfer Control instruction, the Carry Test
bit (bit 21) is set and either the Compare Data (bit 18)
or Compare Phase (bit 17) bit is set.
•
A Transfer Control instruction is executed with the
reserved bit 22 set.
•
A Transfer Control instruction is executed with the
Wait for Valid phase bit (bit 16) set while the chip is in
target mode.
•
A Load/Store instruction is issued with the
memory address mapped to the operating registers of
the chip, not including ROM or RAM.
•
A Load/Store instruction is issued when the
register address is not aligned with the memory
address.
•
A Load/Store instruction is issued with bit 5 in the
DMA Command (DCMD) register cleared or bits 3 or
2 set.
•
A Load/Store instruction when the count value in the
DMA Byte Counter (DBC) register is not set at 1 to 4.
•
A Load/Store instruction attempts to cross a Dword
boundary.
•
A Memory Move instruction is executed with one of
the reserved bits in the
DMA Command (DCMD)
register set.
•
A Memory Move instruction is executed with the
source and destination addresses not aligned.
•
A 64-bit Table Indirect Block Move instruction is
executed with a selector index value greater than
0x16.
•
If the Select with ATN/ bit 24 is set for any I/O
instruction other than a Select instruction.