Serial ATA: Is it 1.5Gbps or 150MBps?

[Rod Speed]

Yup. Pity that bytes aren't sent over a serial interface, but bits.

With modems you used to call them "baud".

For a different concept.

Depending on (lengtht of) start and (number of) stopbits

Mangled all over again.

 

[nuke]

SATA is currently 150MB/sec. 1.5Gb/sec is just wrong.

The correct figure by specification is indeed 1.5 gigabits per second.

Serial ATA I always runs at this speed.

This corresponds with a parallel ATA figure of 150 mega-bytes per second. Some
of the bits are consumed in encoding. Parallel ATA has always figured rates
based on maximum data throughput during the clocking of 16-bit words across the
interface.

 

[Folkert Rienstra]

The correct figure by specification is indeed 1.5 gigabits per second.

Serial ATA I always runs at this speed.

This corresponds with a parallel ATA figure of 150 mega-bytes per second.
Nope.

Some of the bits are consumed in encoding.

Yes, two out of 10 of them, obviously.

The Serial protocol will take several bytes off of that and leave less than
150MB/s. Then the ATA protocol will do the same and leave even less.

Parallel ATA has always figured rates based on maximum data
throughput during the clocking of 16-bit words across the interface.

Right, but those type of figures are misleading as the datarate of the bus
is not the same as the user data rate since command overhead and protocol overhead take their own bite out of that.