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       INPUT/OUTPUT ACCESS:
       ----------------------------------------------------------------
       CALL IO controls the 9901 CRU chip. Sound lists can be played
       independently of current status. (i.e. type in a program while
       playing music from VDP/GROM.) Control Register Unit can turn
       on/off single bits of CRU address bus. (i.e. cards/chips)
       Cassette direct bus control. (i.e. no menu input/output, verify)
                                     
       REDO KEY RESTORED (Was removed in RXB2001 to RXB2012):                                             
       ----------------------------------------------------------------
        The REDO (FCTN 8) is RESTORED in RXB2015. USER needed a buffer
       that would not be molested or modified by CALL LINK, CALL LOAD
       or routines that need a buffer and usually use the same area
       that USER previously used. So to update and eliminate questions
       of compatibility the USER buffer was installed in place of the
       Edit recall buffer (REDO). The REDO key was not considered to be
       of much use anyway as the Crunch Buffer is 163 tokens long and
       in non-tokenized form the Edit recall buffer is only 152 bytes
       long. That is why when REDO is pressed only part of the line
       last typed in was recalled to screen. Additionally COPY lines,
       and MOVE lines commands can do the same thing as REDO could, so
       not much of anything is lost because it is assumed a TEXT EDITOR
       will be used to create programs in RXB then use CALL USER.
 
       PROGRAM DEVICE NAMES ACCESS:
       ----------------------------------------------------------------
       New access names established as devices are now available. By
       using any TRUE DSR (Device Service Routine) you may now access
       the Editor Assembler main menu by typing 'EA' within Basic or
       RXB. Example:  RUN "EA" or OLD EA or DELETE "EA"
       You may also access RXB from Editor Assembler or Basic or even
       another cartridge. Example: OLD XB or DELETE "XB" from Basic.
       At any Editor Assembler device prompt type 'XB' then enter.
 
       FOR ASSEMBLY LANGUAGE PROGRAMMERS:
       -----------------------------------------------------------------
       CALL MOVES is a new command that is a GPL command converted and
       added to RXB to give total control over every type of memory with
       in the TI-99/4A. MOVES works with address or strings to copy,
       over-write or move blocks of memory of any type of memory. RAM,
       VDP, GROM, GRAM, and ROM can be accessed by CALL MOVES.