4 ms·
SDRAM's interface doesn't leave room for extra commands, it's pretty much designed to read/store data and refresh content. It only has 3 lines to select the com
by tcas 12y ago
SDRAM's interface doesn't leave room for extra commands, it's pretty much designed to read/store data and refresh content. It only has 3 lines to select the command (RAS#, CAS#, WE#).
Other RAMs/Flash with different interfaces (e.g. SPI) require a prefix command to be sent over the wire, so it's easier for them to implement things like chip id commands.
- kenz0r 12y agoI don't think that is exactly true. DRAM from SDRAM up has had a number of mode registers to control the ram. More info here: http://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory#SDRAM_mode_register http://en.wikipedia.org/wiki/Synchronous_dynamic_random-acce...
- cnvogel 12y agoExactly. ...here's the table for command accesses on DDR4, including the mode register you referred to. http://en.wikipedia.org/wiki/DDR4_SDRAM#Command_encoding http://en.wikipedia.org/wiki/DDR4_SDRAM#Command_encoding