Atari 400 Technical Reference Manual page 28

GET CHARACTERS -- Read n Characters
(B~te-Aligned
Access)
The specified number of characters are read from the device/file
to the user-supplied buffer. EOL characters have no termination
features when using this function; there can be no EOL, or many
EOL's. in the buffer after operation completion. There is a
special case provided that passes a single byte of data in the
6502 A register when the buffer length is set to zero.
You set the following IOCB parameters prior to calling CIO:
COMMAND BYTE
=
$07
BUFFER ADDRESS = pointer to data buffer.
BUFFER LENGTH
=
number of bytes to read; if this is zero,
the data will be returned in the 6502 A register only.
The CIO alters the following IOCB parameters as a result of the
GET CHARACTERS operation:
STATUS = result of GET CHARACTERS operation.
BYTE COUNT/BUFFER LENGTH = number of bytes read to the
buffer. The BYTE COUNT will always e~ual the BUFFER LENGTH
except when an error or an end-of-file condition occurs.
PUT CHARACTERS -- Write n Characters (Byte-Aligned Access)
The specified number of characters are written from the user-supplied
buffer to the device/file. EOL characters have no buffer
terminating properties, although they have their standard meaning
to the device/file receiving them; no EOL's are generated by CID.
There is a special case that allows a single character to be
passed to CIO in the 6502 A register if the buffer length is
zero.
You set the following IOCB parameters prior to initiating the PUT
CHARACTERS operation:
COMMAND BYTE = SOB
BUFFER ADDRESS = pointer to data buffer.
BUFFER LENGTH = number of bytes of data in buffer.
The CIO alters the following IOCB parameter as a result of the
PUT CHARACTERS operation:
STATUS
=
result of PUT CHARACTERS operation.
OPERATING SYSTEM C016555 -- Section 5
43