On: Why SATA is now obsolete

[__david__]

It depends on what kind of RAM and what kind of bus you are using. Some do let you write bytes at a time, others only allow N byte words at a time.

Though I suppose a byte is still not a bit! I'm not sure I've ever seen a bus interface that addressed individual bits…

[Peaker → __david__]

But the read and write are symmetric, of same sizes.

[__david__ → Peaker]

No: some buses let you write different sized words to the memory controller or RAM chip. For example, picture a bus that's 32 bits wide, but there are control lines that let you specify that you're writing (or reading) 1 byte, 2 bytes, or 4 bytes. During a single byte wide bus cycle you are not sending 4 bytes to the part, even though there are 32 bits connecting to it.

Certainly not everything out there is byte addressable, but neither can one say unequivocally that all RAMs have large atomic word sizes.

[Peaker → __david__]

Again, in your scenario read&write are symmetric. In Flash, they're not.

[__david__ → Peaker]

I don't understand what you mean by "symmetric". If I can write a 32 bit word out and read 1 byte of it back, I don't consider that "symmetric".