OSBYTE &AD

OSBYTE &AD (173) - Read address of keyboard translation table

On entry: newvalue = (oldvalue AND Y) EOR X

On exit: X=high byte of address of keyboard translation table or keyboard number. See OSBYTE &AC.

The top bits indicate if the MOS keyboard driver is being used or an alternative keyboard driver is being used.

• If Y=%11xxxxxx, MOS keyboard driver
• If Y=%10xxxxxx, sideways ROM keyboard driver
• If Y=%0xxxxxxx, International keyboard driver.

If Y<>%11xxxxxx (ie Y < &C0), the byte holds the keyboard number and implementation-specific flags:

• b0-b4 : keyboard number &00-&1F, &00=none or default
• b5
• b6  : International keyboard drive: NUL needed flag
• b6-b7 : MOS or external keyboard driver

See Also

• OSBYTE &AC
• http://mdfs.net/Docs/Comp/BBC/OsbyteA6

Jgharston 22:24, 26 May 2009 (UTC) Jgharston (talk) 21:52, 13 September 2019 (CEST) Jgharston (talk) 03:26, 15 October 2020 (CEST)