848-863



     150 PRINT "DELETING..."
     200 PRINT "DELETED!"

     See COMPUTE!, August 1981, for a sample of this powerful
     technique. See Santa Cruz's Tricky Tutorial #1 (display lists) for
     another application. The last four bytes (844 to 847; $34C to $34F
     in this case) are spare (auxiliary) bytes in all IOCB's.
     When you are in a GRAPHICS mode other than zero, channel
     zero is OPENed for the text window area. If the window is absent
     and you OPEN channel zero, the whole screen returns to mode
     zero. A BASIC NEW or RUN command closes all channels
     except zero. OPENing a channel to S: or E: always clears the
     display screen.
     See COMPUTE!, October 1981,for an example of using an IOCB
     with the cassette program recorder, and September 1981 for
     another use with the Atari 825 printer.

848-863        350-35F        IOCB1
     IOCB one.

864-879        360-36F        IOCB2
     IOCB two.

880-895        370-37F        IOCB3
     IOCB three.

896-911        380-38F        IOCB4
     IOCB four.

912-927        390-39F        IOCB5
     IOCB five.

928-943        3A0-3AF        IOCB6
     IOCB six. The GRAPHICS statement OPENs channel six for
     screen display (S:), so once you are out of mode zero, you cannot
     use channel six unless you first issue a CLOSE#6 statement. If
     you CLOSE this channel, you will not be able to use the
     DRAWTO, PLOT or LOCATE commands until you reOPEN the
     channel. The LOAD command closes channel six; it also closes
     all channels except zero.

944-959        3B0-3BF        IOCB7
     IOCB seven. LPRINT automatically uses channel seven for its
     use. If the channel is OPEN for some other use and an LPRINT is
     done, an error will occur, the channel will be CLOSEd, and
     subsequent LPRINTs will work. The LIST command also uses
     channel seven, even if channel seven is already OPEN. However,
     when the LIST is done, it CLOSEs channel seven. The LOAD
     command uses channel seven to transfer programs to and from