2-34
Functional Description
left in the DMA FIFO. To make this calculation, subtract the
seven least significant bits of the DBC register from the 7-bit
value of the
register. AND the result with
0x7F for a byte count between zero and 112.
If the DMA FIFO size is set to 944 bytes (bit 5 of the
register is set), subtract the 10 least significant
bits of the
register from the 10-bit
value of the DMA FIFO Byte Offset Counter, which consists of
bits [1:0] in the CTEST5 register and bits [7:0] of the
register. AND the result with 0x3FF for a byte count
between zero and 944.
Step 2.
Read bit 7 in the
and
registers to determine if any bytes are left in the
register. If bit 7 is set in the
SSTAT0 or SSTAT2 registers, then the least significant byte or
the most significant byte is full.
Step 3.
If any wide transfers have been performed using the Chained
Move instruction, read the Wide SCSI Receive bit (
, bit 0) to determine whether a byte is left
in the
register.
Synchronous SCSI Receive –
Step 1.
If the DMA FIFO size is set to 112 bytes, subtract the seven
least significant bits of the
register
from the 7-bit value of the
register. AND
the result with 0x7F for a byte count between zero and 112.
If the DMA FIFO size is set to 944 bytes (bit 5 of the
register is set), subtract the 10 least significant
bits of the
register from the 10-bit
value of the DMA FIFO Byte Offset Counter, which consists of
bits [1:0] in the CTEST5 register and bits [7:0] of the
register. AND the result with 0x3FF for a byte count
between zero and 944.
Step 2.
Read the
register and examine bits
[7:4], the binary representation of the number of valid bytes in
the SCSI FIFO, to determine if any bytes are left in the SCSI
FIFO.
Содержание LSI53C896
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 88: ...2 62 Functional Description...
Страница 112: ...3 24 Signal Descriptions...
Страница 306: ...6 38 Specifications This page intentionally left blank...
Страница 310: ...6 42 Specifications This page intentionally left blank...
Страница 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Страница 340: ...6 72 Specifications...
Страница 346: ...A 6 Register Summary...
Страница 362: ...IX 12 Index...