LSI LSI53C896, Technical Manual

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Block Move Instructions 5-13
TC[23:0] Transfer Counter [23:0]
This 24-bit field specifies the number of data bytes to be
moved between the LSI53C896 and system memory. The
field is stored in the
DMA Byte Counter (DBC) register.
When the LSI53C896 transfers data to/from memory, the
DBC register is decremented by the number of bytes
transferred. In addition, the
DMA Next Address (DNAD)
register is incremented by the number of bytes
transferred. This process is repeated until the DBC
register is decremented to zero. At this time, the
LSI53C896 fetches the next instruction.
If bit 28 is set, indicating table indirect addressing, this
field is not used. The byte count is instead fetched from
a table pointed to by the
Data Structure Address (DSA)
register.
MSG C_D I_O SCSI Phase
0 0 0 Data-Out
0 0 1 Data-In
0 1 0 Command
0 1 1 Status
1 0 0 Reserved-Out
1 0 1 Reserved-In
1 1 0 Message-Out
1 1 1 Message-In
*