Motorola CPU32 Reference Manual page 319

Operand Data:
None
Result Data:
Requested data is returned as either a word or long word. Byte data is
returned in the least significant byte of a word result. Word results return 16
bits of significant data; long-word results return 32 bits. Status of the read
operation is returned as in the READ command: $Oxxxx for success, $10001
for bus or address errors.
7.2.8.11 Fill Memory Block (FILL)
FILL is used in conjunction with the WRITE command to fill large blocks of
memory. An initial WRITE is executed to set up the starting address of the block
and to supply the first operand. Subsequent operands are written with the FILL
command. The initial address is incremented by the operand size (1, 2, or 4)
and is saved in a temporary register. Subsequent FILL commands use this
address, increment it by the current operand size, and store the updated
address back in the temporary register.
NOTE
The FILL command does not check for a valid address in the
temporary register - FILL is a valid command only when
preceded by another FILL or by a WRITE command. Otherwise,
the results are undefined. The NOP command can be used for
inter-command padding without corruptng the address pOinter.
The size field is examined each time a FILL command is given, allowing the
operand size to be altered dynamically.
MOTOROLA
7-26
DEVELOPMENT SUPPORT CPU32 REFERENCE MANUAL