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D
UMODEM File Transfer Formats
This Appendix provides a detailed explanation of the
three file transfer formats provided by the UMODEM
program and gives some usage considerations for
specific applications.
UMODEM protocol provides for binary, ASCII 8-bit, and
ASCII 7-bit transfers.
UMODEM is described in the
~
UNIX PC UNIX System V User's Manual.
The paragraphs
below discuss transfers of each type both to and from a
UNIX PC.
Sending Files from a UNIX PC
Binary
The file is sent exactly as it exists on
the disk except that the end of the file
is padded out to a multiple of 128 bytes,
using the NULL character.
ASCII 8-bit
Carriage returns are added in front of
each newline character in the file.
The
end of the file is padded out to a
multiple of 128 bytes using the control-Z
character.
At least one control-Z
character always appears at the end of the
file.
This treatment allows text files to
be sent to MS-DOS and CP/M systems.
ASCII 7-bit
This transfer is the same as sending ASCII
8-bit above, except that the high-order
bit of each character is set to
o.
This
treatment allows certain word processing
files that set high-order bits to be
viewed on the receiving system.
D-l
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