Here is the firmware of the 1570, 1571 and 1571CR drives. There are some differences between these drives. The 1570 is single-sided, while the others are double-sided. See the README file for details.
Mirror sites: FUNET (ftp http) ibiblio.org (ftp http) – General information – File types – CD-R snapshots – Data transfer
cbm-adm@ftp.funet.fi