65C816 machine language
6502/65C02 machine language
CP/M (with Z80 card)
DOS 3.2: You can use DOS 3.2 applications on your Apple IIGS, but you have to load the START13 program from the DOS 3.3 System Master disk.
The Apple IIGS supports six different video display modes. The mode used depends on the software, although you can alternate between 40 and 80 columns by using the Control Panel Program.