Simon's BASIC added an array of features to Commodore BASIC 2.0:
- 114 additional keywords
- commands to ease the coding of sprites
- commands to ease the coding of high-resolution and multicolor graphics
- commands to ease the coding of sound
- commands to aid in structured programming
- keywords to assist in writing and editing BASIC programs, similar to those in the VIC-20 Programmer's Aid cartridge
Programs written in Simon's BASIC could employ hexadecimal numbers in assignments and calculations by including a $ prefix, or binary numbers by utilizing a % prefix.
Because a portion of the cartridge data is mapped into memory at addresses $8000–$9FFF, which overlaps part of the standard C64 BASIC RAM, the amount of available memory for BASIC programs was 8 KB less than that of a standard C64 configuration.