What's the difference?

What's the difference between ATA100, ATA133, ATA150, ect.? And what excatly does each one mean? I've tried looking for it but didn't find anything.

Quite simply, the higher the number the faster the maximum possible read/write speed of the hard drive (subject to the physical limitations of the hardware, of course - it might come from the drive's on-board cache at that rate, but sustained transfers are usually much lower than the theoretical maximum due to physical/mechanical limitations). ATA100 has a theoretical maximum transfer rate of 100Mbps, ATA133 of 133Mbps, etc.

>>2


Thank you sir.

Also forgot to mention that any parallel IDE drive of ATA66 or above requires an 80 wire ribbon connector instead of the older 40 wire (which you still find used on CD/DVD-ROM drives) - there aren't more pins in the connectors, just the same 40 wires, with 40 ground wires interlaced to help reduce noise and interference on the data lines allowing for the higher transfer rates. You won't find any sub-ATA66 drives new nowadays anyway, but it's an important point to note.

The number refers to the clock speed of the IDE bus.  For example, ATA133 means that the clock for the IDE bus is 133MHz.  Don't ask me about the total theoretical throughput for each speed, though.

>>5
No, it refers to the maximum theoretical transfer rate. The clock speeds are a bit more complicated than that. The IDE interface is usually part of the south bridge, and thus tied to the PCI bus speed (or multiples thereof). SATA on the other hand uses a vastly higher clock rate (because it's only tranferring one bit at a time - serial). SATA-150 for example has a clock rate of 1500MHz, but a transfer bandwidth of 150Mbps (way beyond what modern hard drives can sustain).

IDE is a 16-bit bus (actually an ad-hoc reformatting of ISA, hence the name "AT Attachment"), so the clock speed on the wire is actually about half the rated transfer rate. For example, the fastest pre-UDMA mode, multiword DMA 2/PIO 4, ran at 16.6 MB/s, which comes to a clock speed of 8.33 MHz, which is the same as ISA (actually EISA, which is what IDE DMA was originally meant to work with; remember, PCI didn't come of age until 1995 or so).