chs addressing with 28 bits (eide and ata-2) permits eight bits for sectors still starting at 1, i.e., sectors 1…255, four bits for heads 0…15, and sixteen bits for cylinders 0…65535. this results in a roughly 128 gb limit; actually codice_23 sectors corresponding to 130560 mb for a sector size of 512 bytes. the codice_24 bits in the ata-2 specification are also covered by ralf brown's interrupt list, and an old working draft of this now expired standard was published.