# Cable transfer speeds

#### MoonPig

Hi,

I'm writing about cable transfer rates for some Assignment work for College. But the internet isn't been clear on actual speeds. Basically I need to know what the real speeds are for:

SATA (it claims 1.5Gbps, 3Gbps and 6GBps. But other things claim 300Mbps)
IDE (claims 133Mbps)
Floppy Cable (can't find anything on it)

#### Urbklr

Sata 1 150MB's
Sata 2 300MB's
IDE 133MB's
Is floppy the same as IDE?

I think those are right, someone will correct me if wrong.

#### ghost101

##### New Member
Sata 1 150MB's
Sata 2 300MB's
IDE 133MB's
Is floppy the same as IDE?

I think those are right, someone will correct me if wrong.
Nope its 192MB/s, 384MB/s, if you convert from1.5gbps and 3gbps. But the wikipedia article says.

SATA 1.5 Gbit/s SATA 3 Gbit/s
Frequency 1500 MHz 3000 MHz
Bits/clock 1 1
8b10b encoding 80% 80%
bits/Byte 8 8
Real speed 150 MB/s 300 MB/s

Not sure why the real speed isnt a straight conversion.

edit: whats 8b10b encoding?

#### MoonPig

yea, thats whats confusing me. Its claiming Gbps but saying 'real' speeds in Mbps :/

#### ghost101

##### New Member
yea, thats whats confusing me. Its claiming Gbps but saying 'real' speeds in Mbps :/
Thats simply a bits to bytes conversion. 8 bits per 1 byte. But its not a straight conversion in this case due to 8b10b encoding. Not sure what that is.

The calculations are like this

1500mhz with 1 bit per cycle. So 1.5 gbits per second. But for some reason only 80% is used meaning 1.2gbps. This 1.2Gbps/8 = 150MB/s.

I don't know if these are Gib/Mib. If yes the calculations are slightly different. Probably not Gib and Mib since thats the standard hard drives follow and the wikipedia calculations then make sense.

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#### MoonPig

ah ok, thanks alot. That makes sense now.