1、memory

Byte Enable in Embedded Memory Blocks
The  embedded memory blocks support byte enable controls:
• The  byte enable controls mask the input data so that only specific  bytes of data are written. The
unwritten bytes retain the values written previously.
• The  write enable ( wren ) signal, together with the byte enable ( byteena ) signal, control the write
operations on the RAM blocks. By default, the  byteena  signal is high (enabled) and only the  wren
signal controls the writing.
• The  byte enable registers do not have a  clear  port.
• If you are using parity bits, on the M20K blocks, the byte enable function controls 8 data bits and 2
parity bits; on the MLABs, the byte enable function controls all 10 bits in the widest mode.
• Byte enables operate in a one-hot fashion. The  LSB of the  byteena  signal corresponds to the LSB of the
data bus.
• The  byte enable signals are active high.