What is this strange memory configuration of a SRAM device?

[BGA]

Memory Configuration....

I'm searching for SRAM device to use with a Analog ADSP-21160.
I don't understand the memory configuration of the device I found!
256K x 36
512K x 36
1Meg x 18....
Why this strange format? Why not a data widht of 16 or 32 bit?

 

[gabby]

Hi
some kind of application need for evry8bit 1bit aditional for test and repair
some type of memory controllers test that bit to be sure that the data not
fail.(is an inportant safety bit in importat system or servers)

As you know in computer you can find memory that have the aditional
option that called ECC that also the aditional bit.

Best regards. 8)

 

[ted]

... and I would add: If the device with x18 /x36 architecture is otherwise suitable, available, and of right price (and you do not need error checking or correction (parity / ECC)), you can use them and leave the extra bits unused. However, you should use for example a weak pull-up or pull-down on those extra data lines to prevent them to settle halfways between logic levels: It is not good - it may lead to excessive power dissipation and reliability problems.

Ted

 

[BGA]

Thanks a lot for the fast replay.