ATA/100 vs. ATA5/UDMA100 what's the diff?

[Johnny]

Can't get maxtor 20.4 gig to work on my A7V ATA 100 controller. On boot up it is listed as the ATA5 mode disk. Is this the problem?

 

[Richard]

UDMA 5 is the equivalent of ATA-100.

 

[Johnny]

Thanks