- APPENDIX F -

IKBD SCAN CODES

IKBD Scan Codes

The AES, VDI, and BIOS, all contain functions which return scan codes from the Intelligent Keyboard Controller (IKBD). These scan codes can be used to determine exactly which key was struck (not simply the ASCII value).

One thing that must be considered when relying on scan codes is that they identify a physical vector on the keyboard, not a key definition. The scancode for a letter on an American keyboard, for instance, may be different than the scancode for the same letter on a German keyboard. The XBIOS function Keytbl() can be used to look up the ASCII value assigned to a scancode to ensure that keystrokes are correctly processed.

Scancodes for keyboard modifiers (SHIFT, ALT, etc.) are never returned by an OS call. However, when handling the IKBD directly, the following scancodes may be encountered:

The values shown in the following table contain the IKBD scancode of each keyboard key in the high BYTE and the ASCII code in the low BYTE. Keys with no corresponding ASCII value will always have zero as the low byte. These values are valid for all Atari computers with US keyboards: