A couple of weeks back, I was sent a replacement hard disk drive for my work PC. After backing up my data and opening up my notebook PC, I found that the replacement was actually a Seagate ST980825AS Serial ATA (SATA) drive, rather than an ST9808211A Ultra ATA (EIDE) disk. Although the new disk drive is much faster, unfortunately it won’t actually fit my laptop; but I did come across this useful guide to interpreting Seagate disk drive model numbers.