944-959



     (E:)          13        Screen input and output

     E: BIT 0 equals one is a forced read (GET command).

     Keyboard       4        Read

     Printer        8        Write

     RS-232         5        Concurrent read
     serial         8        Block write
     port           9        Concurrent write
                   13        Concurrent read and write

                             Clear      Text      Read
                             Screen     Window    Oper-
                             after GR.  also      ation

     Screen         8        yes        no        no
     display       12        yes        no        yes
     (S:)          24        yes        yes       no
                   28        yes        yes       yes
                   40        no         no        no
                   44        no         no        yes
                   56        no         yes       no
                   60        no         yes       yes

     Note that with S:, the screen is always cleared in GR.0 and there
     is no separate text window in GR.0 unless specifically user-
     designed. Without the screen clear, the previous material will
     remain on screen between GRAPHICS mode changes, but will
     not be legible in other modes. The values with S: are placed in
     the first auxiliary byte of the IOCB. All of the screen values above
     are also a write operation.

     The second parameter in an OPEN statement (placed in the
     second auxiliary byte) is far more restricted in its use. Usually set
     to zero. If set to 128 ($80) for the cassette, it changes from normal
     to short inter-record gaps (AUX2).

     With the Atari 820 printer, 83 ($53; AUX byte two) means
     sideways characters (Atari 820 printer only). Other printer
     variables (all for AUX2 as well) are: 70 ($4E) for normal 40
     character per line printing and 87 ($57) for wide printing mode.
     With the screen (S:), a number can be used to specify the
     GRAPHICS modes zero through eleven. If mode zero is chosen,
     then the AUX1 options as above are ignored.
     For the ICCOM field, the following values apply (BASIC XIO
     commands use the same values):

     Command                       Decimal   Hex
     ----------------------------------------------------------------------
     Open channel                      3       3