Workbench Version 1.2 was the first to support Kickstart stored in a ROM. Kickstart disk was still necessary for Amiga1000 models, but it was no longer necessary for Amiga500 or 2000, but the users of these systems must change the ROMs (which were socketed) to change the kickstart version.

AmigaOS now spanned two floppy disks, and supported installing and booting from hard drive (assuming the Amiga was equipped with one), the name of the main disk was still named "Workbench" (the user interface portion of the operation system). The second disk was the Extras disk. AmigaOS set of disks was still three disks, due to abolition of Kickstart disk. Users of A1000 could ask a Commodore dealer to obtain one. The third disk was now AmigaBasic by Microsoft.

Kickstart Version 1.2 corrected various flaws and added AutoConfig support. AutoConfig is a protocol similar to and is the predecessor of Plug and Play, in that it can configure expansion boards without user intervention.