Avago Technologies LSI53C1010R - Manual (Page 262)

5-14 SCSI SCRIPTS Instruction Set
Version 2.2 Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
TC[23:0] Transfer Counter [23:0]
This 24-bit field specifies the number of data bytes to be
moved between the LSI53C1010R and system memory.
The field is stored in the
DMA Byte Counter (DBC) register.
When the LSI53C1010R 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 LSI53C1010R
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 ST Data-Out
0 0 1 ST Data-In
0 1 0 Command
0 1 1 Status
1 0 0 DT Data-Out
1 0 1 DT Data-In
1 1 0 Message-Out
1 1 1 Message-In