APPENDIX TWELVE



     The OS VBLANK process now copies the PORTA joystick (0-1)
     and paddle (0-3) values into the shadow registers for PORTB so
     that STICK0 affects both STICK0 and STICK2, STICK1 affects
     STICK1 and STICK3, PADDL0 affects PADDLE0 and PADDL4, and
     so on.

640-643        280-283        PTRIG4-7
     No longer in use (see PADDL4-7).

646-647        286-287        STRIG2-3
     No longer in use (see STICK2-3).

648            288            HIBYTE
     High-byte register for relocatable loader routine.

651            28B            IMASK
     Unused.

652            28C            JVECK
     Temporary jump vector; unused.

654,655        28E,28F        NEWADR
     Used by relocatable loader; new address vector.

668            29C            CRETRY
     Number of command retries; moved from 54 ($36) in the
     400/800.

701            2BD            DRETRY
     Number of device retries; moved from 55 ($37) in the 400/800.

713,714        2C9,2CA        RUNADR
     Run address register for relocatable loader routine.

715,716        2CB,2CC        HIUSED
     Used by relocatable loader routines.

717,718        2CD,2CE        ZHIUSE
     Used by relocatable loader routines.

719,720        2CF,2D0        GBYTEA
     Used by relocatable loader routines.

721,722        2D1,2D2        LOADAD
     Used by relocatable loader routines.

723,724        2D3,2D4        ZLOADA
     Used by relocatable loader routines.