The
employed, thus permitting equipment options designed
to the user's communications network and his opera
ting modes.
transfer between core storage and the communications
facility. The
assembly on data being read into core storage and
character disassembly on information passing in the
opposite direction.
A
for attaching synchronous terminals (or stations) to
the
optionally available for communicating in EBCDIC,
operations. The method used in error detection
varies depending on the transmission code used. The
employed) of a specific code type.
(e. g., Telegraph Terminal Controls or IBM Terminal
Controls) are permissible provided only two
are installed per
with one
The three transmission codes available are:
EBCDIC--Extended Binary-Coded-Decimal Inter
change Code. This eight-bit code allows trans
mission of 256 different bit patterns. Ten (option
ally eleven with ITB) of these bit patterns represent
data-link characters assigned as line-control
characters. In
are currently assigned in EBCDIC:
52 alphabetic characters (upper and lower case)
22 end-to-end characters
33 special graphics (including space)
EBCDIC is code-compatible with the internal code
used in
utilization of communications facilities and of
channel-to-control-unit data paths to the
storage directly as received without need for trans
lation. For the
position 7 of the byte in main storage is always trans
mitted onto the communications line as the first bit.
The first bit received from the transmission facility
always goes to bit-position 7 of the byte in main
storage.
Information Interchange. * The
of seven data bits plus an odd-parity check bit in the
eighth bit position.
patterns, all of which have assigned characters as
follows:
52 alphabetic characters (upper and lower case)
23 end-to-end characters
33 special characters (including space and delete)
facility. Figure 12 gives examples of code trans
lations of a received character to EBCDIC or
transmission of 64 bit patterns assigned the following
characte r repre sentations:
26 alphabetic characters (upper case)
12 special characters
6 end-to-end characters
code for information entry from remote card
machines not requiring the extended code of EBCDIC.
Transmission-Code Transparency
Each of the three transmission codes may be used
in transparent-text mode. Transparency permits the
unrestricted use of all bit patterns, within each
transmission-code type, to be transmitted and
received as strictly a binary-bit stream, using a
special procedure for control-character recognition.
transparent-text mode is useful in transmitting
messages as:
Fixed-point data
Floating-point data
Packed-decimal digits
Logical information
*This code is compatible with the
not imply full compatibility with non-IBM synchronous
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