what is Data Mask in RAM

[Ivanw]

data mask ram

:?: I saw a RAM chip define two pins as Data Mask , and they are LDQM & UDQM .
What is "Data Mask" ? Mask the output data ?

 

[clivechen]

mask of ram

i think the mask is that you must distinguish the rams with others. so you need a mask!
you can see the website
https://www.esrf.fr/computing/scientific/FIT2D/FIT2D_REF/node205.html

 

[vomit]

:?: I saw a RAM chip define two pins as Data Mask , and they are LDQM & UDQM .
What is "Data Mask" ? Mask the output data ?

The RAM chip is apparently 16-bits wide. So each write affects 16 bit. If you only want to write the lower or upper byte and keep the other byte untouched, you must mask off the other byte using the Upper DQ Mask or Lower DQ Mask, respectively.

For 32-bit chips you'll find 4 mask pins, etc.