ZiLOG Z80-RIO Operating System User's Manual page 141

6.2
ASSIGN
ASSIGN
Request vector:
Logical unit
Request code - 02 or 03
Data transfer area - ignored
Length - ignored. Zero will be returned.
Completion return address
Error return address
Completion code
Supplemental parameter information - pointer to
area containing the following:
Action:
1st byte of area - ignored by ZOOS.
(This byte does control system
functions however. See Section 3.3.),
2nd byte of area - character designating
physical disk drive, either '0' through
'7', or
'*'.
3rd byte of area - length in bytes of file
name. A 0 length name indicates
a
scratch file. The maximum length name is
32 characters.
4th and following bytes - the filename.
The filename given is associated with
(assigned to) the given logical unit for
subsequent I/O operations. Any previous
assignment to the same logical unit is
nullified. The filename is stored in a
buffer for later use when the logical
unit is opened. When the file is
opened, the filename is removed from
the buffer. Thus, if a file is
opened and closed, there must be a
new assignment before it can be
reopened.
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