Motorola MVME2300 Series - Manual (Page 209)

Programming Model
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rom a en When rom a en is set, accesses to Block A ROM/Flash in
the address range selected by ROM A BASE are enabled.
When rom a en is cleared, they are disabled.
rom a we When rom a we is set, writes to Block A ROM/Flash are
enabled. When rom a we is cleared, they are disabled.
Note that if rom_a_64 is cleared, only one-byte writes are
allowed. If rom_a_64 is set, only four-byte writes are
allowed. The Falcon ignores other writes. If a valid write
is attempted and rom a we is cleared, the write does not
happen but the cycle is terminated normally. Refer to
Table 3-16 for details of ROM/Flash accesses.
Table 3-16. Read/Write to ROM/Flash
Cycle
Transfer
Size
Alignment rom_x_64 rom_x_we Falcon Response
Write 1-byte X 0 0 Normal termination, but
no write to ROM/Flash
Write 1-byte X 0 1 Normal termination,
write occurs to
ROM/Flash
Write 1-byte X 1 X No Response
Write 4-byte Misaligned X X No Response
Write 4-byte Aligned 0 X No Response
Write 4-byte Aligned 1 0 Normal termination, but
no write to ROM/Flash
Write 4-byte Aligned 1 1 Normal termination,
write occurs to
ROM/Flash
Write 2,3,5,6,7,
8,32-byte X X X No Response
Read X X X X Normal Termination