Texas Instruments 990 Operation Manual page 237

Jd75\ _ _ _ _ _ _ _
~
945255-9701
C.2 DATA TERMINAL CHARACTERS
The remainder of this appendix presents a detailed summary of the characters recognized by the
733 ASR Data Terminal in accordance with 990 file and record specifications. These include the
data and control characters recognized by the terminal keyboard, printer, cassette receiving input
data, and cassette sending output data. In each case, the ways in which the control characters
function are described.
The character sets for each I/O function are diagrammed in figure C-l to show the character
corresponding to each ASCII code value and its function.
The ASCII control characters are shown in table C-3.
C.2.1 733 ASR TERMINAL KEYBOARD INPUT. Refer to figure C-l.
Peripheral device: 733 ASR terminal keyboard.
Physical organization: Character, record, file.
Record and file ending characters:
End of record: CR
End of file: DC3.
Character set: As shown. Except as indicated, all characters are automatically echoed as
themselves.
Control character functions:
1. BS echoes as LF ,BS and deletes the last character entered in the user's buffer (CTRL
H).
2. DEL echoes as LF,CR and deletes the current input record.
3. HT causes a single space to be echoed. HT is placed in the user's buffer.
4. DC3 received as the first character of a record indicates end of file and terminates the
input record. DC3 is not placed in the user's buffer.
5. CR echoes as CR and is not placed in the user's buffer. CR terminates the input
record.
6. LF echoes as LF and is not placed in the user's buffer.
7. Characters in the range 20
16
to 7E
16
are echoed and placed in the user's buffer.
8. The most significant bit in each character is set to zero
in
the user's buffer.
9. ESC aborts current output and returns a write error to the user's program.
10. All other characters are ignored.
C-3
Digital Systems Division .