Atari 400 Technical Reference Manual page 86

intere9t to you, however.
FORMAT DISK (Command Byte
=
$21)
The Handler commands the diskette controller to format the entire
diskette and then to verify it. All bad sector numbers (up to a
maximum of 63)
are
returned and put in the supplied buffer,
followed by two bytes of a l i i ' s ($FFFF). You set up the
following DCB parameters prior to calling the Diskette Handler:
COMMAND BYTE
=
$21.
DEVICE NUMBER
=
disk drive number (1-4).
BUFFER ADDRESS
=
pointer to your 128-byte buffer.
Upon return, you might be interested in the following DCB parameters:
STATUS BYTE = status of operation.
BYTE COUNT
=
number
of
bytes of bad sector information in
your buffer, not including the $FFFF terminator. If there
are
no bad sectors, the count will e~ual zero.
Serial Bus 1/0
InputlOutput to devices other than the keyboard, the screen, and
the ATARI Computer controller port devices, must utilize the
Serial 110 bus. This bus contains data, control, and clock lines
to be used to allow the computer to communicate with external
devices on this Ifdaisychained" bus. Every device on the bus has
a unique identifier and will respond only when directly
addressed.
The resident system provides a Serial 1/0 Utility (SID), that
provides a standardized high-level program interface to the bus.
SIO is utilized by the resident Diskette, Printer, and Cassette
handlers, and is intended to be used by nonresident handlers (see
Section 9), or by applications, as well. For a detailed
description of the programlSIO interface and for a detailed bus
specification refer to Section 9.
OPERATING SYSTEM C016555 -- Section 5
101