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A single transfer commands consists of a proper Mode Word followed by an Address Word
and, if applicable (a Write command), by the data word.
4.5.12 Block Transfer Commands
A block transfer command consists of a proper Mode Word followed by an Address Word
specifying the starting address of the block. A block cannot cross the 256-byte boundary and,
thus, its maximum length (default) is 256 bytes. If blocks of length shorter than 256 bytes are
to be transfered, the desired length is to be specified in bits 24-31, otherwise this field is to be
left 0x00. In the case of block Write command, the above two words are to be followed by
the data words.
Block transfer terminates upon receipt of bus error BERR and, in the case of
commands, 0xFF..FF is written to the output data stream to signal the fact of such a
termination.
4.5.13 Multiblock Transfer
A multiblock transfer feature allows one to perform a sequence of block transfers with or
without starting address increment for the consecutive blocks and, thus, to read/write large
amounts of data from/to addressable memories and FIFOs. The increment of the starting
addresses for the subsequent block, if not suppressed, is 256 bytes, i.e., 0x100. The starting
address must be on the 256-byte boundary, i.e., to have the least significant byte equal zero.
The block length may be set to less than 256 bytes, in which case noncontiguous memory
locations will be accessed.
To suppress incrementing of the starting addresses of consecutive blocks, such as might be
needed to access long FIFOs, on must set bit 10 (value 0x400) of the Mode word.
In the case when the starting or end address of the desired transfer does not fall on the 256-
byte boundary, single block transfers must be performed to handle the partial blocks, with the
balance of the transfer executed by one multiblock command.
Multiblock transfer terminates upon receipt of bus error BERR and, in the case of Read
commands, 0xFF..FF is written to the output data stream to signal the fact of such a
termination.
4.5.14 Writing Marker Words into the Output Data Stream
Firmware 66000701 and newer allows one to insert marker words into the output data stream
to mark desired locations of data within an event to facilitate viewing and unpacking of the
data buffers. A typical use is to mark the ends of events and ends of long blocks of data. To
write a marker, a two-word Write Marker command must be inserted into the command
stack, such that the Mode Word identifies in its bit 13 (value 0x2000) the command as a
Write Marker command. This Mode Word may be simply 0x2000 (the AM code is
disregarded) and must be followed by a 32-bit marker data data specifying the desired marker
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