Texas Instruments 990 Operation Manual page 118

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The initial message aild the fIrst command, with associated entries, are as follows:
POSITION TAPES, ENTER CR
?IO
W1
START
BSS
RSET
LWPI
CLE
32
W1 .
RO
The I comman4 with an operand of zero causes PX9EDT to place the lines that follow at the
. top of the buffer. The buffer pointer is not moved as lines are entered and remains ahead of the
fIrst line entered. In the above example, an error was made in the operation fIeld of the fourth
line, so the user entered ail additional carriage return to terminate the command, permitting
entry of another command to correct the error.
The next part of the example program is:
?K3
?P1
CLE RO
The K command cuases PX9EDT to write the fIrst three lines on the output medium. The PI
command causes PX9EDT to print the pointer line to verify that the pointer is at the line that
contains the error. An alternative to using the Keep c;ommand to write the correct portion of the
program is to use a Down command to position the pointer for correction of the error, leaving
the fIrst three lines in the buffer.
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The next command and the associated entries are as follows:
?C
CLR RO
11 INC RO
JNO
J1
D1 DEC RO
JNE D1
JMP 11
END START
The C command deletes the error line and accepts seven lines of source code. The example source
program is now complete, with three lines written on the output medium, and seven lines in the
buffer.
The next command and the resulting printing are as follows:
?F10F'J1"11'
LAST LINE
0001.FOUND
The
Ftt~mmand
scans the contents of the buffer, replacing the fIrst appearance in each line of
string J1 with string II. The command attempts to scan 10 lines, and prints the message LAST
LINE because there are only seven . lines in the buffer. The V and P options (paragraph
4.504.5)
could have been used. This
is
an alternate method of correcting an error in a source program
entered from the keyboard using PX9EDT.
4-6
Digital Systems Division.