SCROLL: A Scrolling Editor for OS/8
Darrell J. Duffy
Computer Lab
Department of Physiology and Biophysics
West Virginia University Medical Center
Morgantown, West Virginia
January 1973
Edited by: Thomas W. McIntyre
Current Version SCROLL V11
SCROLL Table of Contents
Preface .................................... 1
Using SCROLL ............................... 2
General Structure .......................... 3
File Edit class commands ................... 4
Creating, Editing, and Deleting ....... 5
Edit Output ........................... 6
Edit Input ............................ 7
Command Line Commands
Text Position commands ............... 10
Text Deletion commands ............... 11
Text String commands ................. 12
X Buffer commands .................... 14
Repeat command ....................... 15
Text Mode Commands
Formating Characters ................. 16
Text Deletion ........................ 16
Cursor Position ...................... 16
Search and Macro ..................... 17
I/O Switches ......................... 18
The Display of SCROLL ..................... 19
Using SCROLL Without Display ......... 20
KBSCRL Display ....................... 21
Auto Tab Insertion ................... 23
Auto Tab for Assembler Users ......... 23
Auto Tab for FORTRAN or BASIC Users .. 24
Switching from DIAL to SCROLL ............. 25
Protecting Files .......................... 28
Advanced Uses of SCROLL
Recovering Overfull Files ............ 29
Extending Files ...................... 29
Recovering Smashed Devices ........... 30
PIP and SCROLL files ...................... 31
Chaining to SCROLL ........................ 33
Patches to SCROLL ......................... 34
Error Messages ............................ 35
Summary of Commands ....................... 37
Preface
SCROLL is a bidirectional editor. This means that
SCROLL edits a single file instead of inputting from a file
and outputting edited text to another file. SCROLL allows
moving through the edit file in either direction with no
restrictions. Formfeed characters within the file provide
convenient markers but do not restrict movement. The file
currently being edited is termed the main file. In addition
there are two files known as auxiliary files which may be
opened. One of these files is for input and one is for
output. These auxiliary files allow merging or splitting of
edit files easily. A page in either the auxiliary files or
the main file is the text delimited by form feeds. Pages
provide the basis for control of some of the editing commands
to SCROLL.
There are two types of commands to SCROLL: Text Mode
commands and Command Line commands. Text Mode commands are
CTRL keys typed in Text Mode and are executed immediately.
CTRL keys are keys typed while the CTRL key on the teletype
is held down. Command Line commands are typed into a special
Command Line buffer which is displayed at the bottom of the
scope.
SCROLL maintains the file as a continuous packed string
of characters. Part of the file is maintained in memory to
be displayed and changed. When too much is added for the
memory to accomodate, the remainder of the file is moved down
to allow room. This is why the block limits of the file must
be greater than the actual size of the text edited. When an
EXIT or QUIT command is done, SCROLL writes out all of the
file from memory so that it is a continuous packed string on
the editing device.
Using SCROLL
SCROLL is distributed as a save file. To run the
program, enter the following line to the OS/8 Keyboard
Monitor's dot.
.R SCROLL
The current version number will be printed out.
One of two commands must be given to SCROLL before it
may do anything else. If you are just starting to create a
new file, you should enter the command:
$EMSYS:FILE.EX$$ _ __
Where $ stands for Altmode. This command will make a 10 _
block file called FILE.EX on the system device. You may now
type in your program text or data or whatever. After
completing this initial editing session, you will want to
return to the OS/8 Keyboard Monitor. The command to return
to the OS/8 Keyboard Monitor from SCROLL is:
$QUIT$$ _ __
The next time you wish to edit the file called FILE.EX
you must use the command:
$EDSYS:FILE.EX$$ _ __
This gets you to the first line of the file. Again, to
return to the OS/8 Keyboard Monitor, enter the command
$QUIT$$ _ __
SCROLL-2
Command Line Commands
General Structure
When Altmode (Escape or Prefix on some terminals) is
typed in Text Mode, Command Mode is entered and any
characters typed are then entered into a Command Line buffer
to be executed as a command. During entry of a Command Line,
RUBOUT and CTRL/U may be used to edit it. RUBOUT removes the
last character entered from the Command Line and CTRL/U
ignores the Command Line and returns to Text Mode. A
carriage return typed into the Command Line is entered as a
CR/LF combination and a linefeed is entered as a linefeed.
When an Altmode is typed, it is stored in the Command Line
unless the previous character was an Altmode. In this case
the command is executed. Before the command is executed it
will be echoed if Command Line echo or full echo is enabled.
Multiple commands may be entered on a Command Line. The
commands are executed in order and any error will cause
termination of the command string at the point of the error.
The commands may, but need not, be separated by single
Altmodes. An Altmode signals three things in the command
line: the end of a string argument to a string command, the
end of the device-filename specification of an Edit class
command, and the relative locate command if it is immediately
preceded by a non zero number. If you find it convenient you
may also separate the commands with a space. Spaces between
commands are ignored. This practice could lead to some
confusion since -3$ moves the cursor back three lines while _
-3 $ does nothing. _
The Command Line commands provide two functions:
Complex editing functions which may be combined for powerful
text manipulation; and control of the I/O facilities of the
editor such as opening and closing of main and auxiliary
files and transfer of text between the main file and the
auxiliary files. All of the commands may be preceded by a
decimal number in the range -2048 to +2047. This number is
an argument to many of the commands and will be ignored if
the command does not use it. All the commands which require
a numeric argument make some useful assumption if the
argument is missing. In the following discussion n denotes a
numeric argument preceding the command.
SCROLL-3
File Edit Class Commands
Edit class commands connect SCROLL with the main and
auxiliary files and control input and output between the main
file and the auxiliary files. EM, ED, EO and EI commands are
followed by an OS/8 standard device-filename specification of
the form dev:filnam.ex. No switches or other options are
recognized except the length of the output file enclosed in
square brackets [ ]. The length if present, must be a
decimal integer with no embedded spaces. The device-filename
specification must be terminated by an Altmode. Embedded
spaces are ignored but must not appear within the square
brackets.
If a filename is entered without an extension, the
following default extensions are used:
.PA .RO
.12 .DA
.FT .BI
.BA .FA
.RA
Each of these extensions is used sequentially. If no file
exists with the given extension, the next extension is tried.
An error results if none of the default extensions work.
Also, auto tab insertion is used for each file depending
on the extension. A 'tri-flop' is used to determine the
auto-tab condition. The three tab stop conditions are
assembler source files, FORTRAN or BASIC source files, and no
tab stops. The CTRL/T command will change the tri-flop value
from its assumed condition. This feature eliminates the need
for a separate FSCROL program for FORTRAN source files. Also
there are no default extensions for output files. DSK: is
assumed if no device is specified.
Note that EM and ED require a directory device. A
filename is also required for ED and EM. Devices for the EO
and EI commands may be either directory or non-directory and
the name may be omitted for non-directory devices. If the
command EO is given with no filename to a file-structured
device, an error will result. However, an EI command may be
given to a file-structured device and no errors will result.
But "garbage" characters will be input starting at block 0 of
the device.
There are several things to note about the edit files
created and maintained by SCROLL. When a file is to be
edited by SCROLL there should be some extra room at the end
of the file to allow for additions. SCROLL will not allow
the file to overflow its area and destroy other files and it
will not allow you to EXIT the file if there is more text
SCROLL-4
than can be held in the file. Since SCROLL does not prescan
the file to find out how much room is left, SCROLL does not
find out there is not enough room in the file until it tries
to EXIT or must shift the file down to make more room. By
this time SCROLL has perhaps as much as three blocks more
text than can be written in the file. The recovery procedure
is fairly easy but it is troublesome to have to recover. It
is much easier to plan the length of the file properly.
SCROLL-5
EMdev:filnam.ex[n] Edit Make. Creates a new file of length
n for editing. The length of the file
may be specified in square brackets
within the device-filename specification.
If no length is specified, 10 is assumed.
Any file of the same name and extension
will be deleted from the specified device
first. This command allows for creation
of large areas on the device for
scrolling. The file is connected with
the editor as the main file so that entry
of text can begin immediately.
EDdev:filnam.ex Edit. Connects a previously created file
with the editor as the main file. The
file should have been created with EM to
allow extra space to make additions.
EXIT This command disconnects the main file
from the SCROLL program gracefully. The
main file is written out. Auxiliary
files are still active if they exist. If
the main file is too long to EXIT, SCROLL
will type EX and return at the end of the
file. EXIT must be spelled out
correctly.
QUIT This command does an EXIT if there is a
main file and returns to the OS/8
Keyboard Monitor. The auxiliary output
file is closed if there is one. If there
is no main file, QUIT simply returns to
the OS/8 Keyboard Monitor. QUIT must be
spelled out.
KILL Completely forgets the contents of the
current main file. The file is not
deleted from the directory or released
from SCROLL. It is simply cleared to
prepare it for new input. The tentative
output file, if there is one, is still
active. KILL must be spelled out.
ABORT This command immediately disconnects the
main file from SCROLL and releases its
handler. An EXIT is not done and the
contents of the main file may not be
correct on the device unless the file was
LOCKed. This command is provided to get
you out of bad situations. It may be
used in place of EXIT, if the file is
LOCKed. ABORT must be spelled out.
SCROLL-6
Auxiliary files are available to the user. These files
may be used to split a large file into smaller ones or to
create a large file from smaller ones. One may also extract
subroutines or other portions of coding from assembly
language files.
Output to the auxiliary file is via the EW and EWP
commands. 100EW$ writes 100 lines of text from the current _
line to the output file. It is usually much easier to insert
a form feed in the main file and execute an EWP command than
to count the lines to be output. The command 2EWP$ will _
output two pages starting with the current line. To output
the current line use the command EW$. _
The EC command closes the auxiliary output file to make
it permanent in the device directory (if file structured).
It may be done at any time and must be done before a second
EO command or the first auxiliary output file will be
discarded. The output file remains active following an EXIT.
This allows merging small pieces of large files into a single
output file. This can be quite useful in editing data sets
into new configurations.
EOdev:filnam.ex Edit Output. Connects a standard OS/8
tentative output file with SCROLL as an
auxiliary file. Output to the file is
via EW and EWP. The file may be closed
via an EC. The length option enclosed in
square brackets [ ] may be used to
specify a maximum length for the file.
The file may be a non-directory device.
In this case the filename and extension
need not be specified. All tentative
output files not yet closed are deleted
by an EO and the output handler is
released.
nEW Edit Write. Write a number of lines of
text to the auxiliary output file
starting with the current line. A file
must have been opened by the EO command.
A positive number n may precede the
command to control how many lines are
transferred. One is assumed. As the
command proceeds, the cursor moves
through the main file. The cursor is
positioned after the last character
transferred by the command. EW may be
stopped by striking a key. The key is
SCROLL-7
ignored as is the rest of the command
line. In the case of stopping the
command, the process may stop in the
middle of the line. The keyboard command
CTRL/V should be used to put that line
back together again before any thing else
is done.
nEWP Edit Write Pages. Same as Edit Write
except only form feeds are counted. One
page is assumed. As before, the output
begins following the current line. If
repeated pages are to be output, use of
EWP1$ to move past the form feed at the _
end of the page will allow the CTRL/K to
be used.
EC Edit Close. The tentative output file is
closed with the required length and the
output handler is released. Note that
the number of blocks specified by the EO
command is checked by EW and if too many
blocks are output, the file is closed
with an EOF at the end. The cursor
position will show one more than the last
character successfully output to the
file.
The EI command allows merging of files into a main file.
Input can be from any OS/8 device or file. The command
EIDTA1:SUBR.PA$ sets up a file on DTA1: for input. _
The ER and ERP commands transfer from the input file.
10ER$ reads 10 lines into the main file. 1PERP$ reads one _ _
page into the file following the current page. ER and ERP
read without auto tab insertion. ES and ESP behave like the
ER and ERP commands except no text is inserted into the main
file. The input is ignored. These commands are used to
position the input file. $EIFILE$ 2ESPERP$$ reads the third _ _ __
page of FILE on device DSK:.
The input file need not be closed. An error occurs if
an attempt is made to read beyond the EOF of the input file.
The error will also occur if the last page is read with an
ERP and it is not ended by a form feed. If you do not read
all of an input file and wish to start reading another,
simply open the new file. The old file will be dropped.
EIdev:filnam.ex Edit Input. Connects a standard OS/8
input file to SCROLL as an auxiliary
file. Input control is via ER, ERP, ES,
and ESP. Non-directory devices may be
used. PTR: may be used to input paper
SCROLL-8
tapes to SCROLL. RUBOUTs and null
characters are not ignored, so if these
occur on the tape it is better to use PIP
to copy the tapes to a directory device
first. (Paper tapes may also be input by
just reading as normal input with the TTY
reader since linefeeds are ignored).
Another EI command supercedes the last
one. No input close command is needed.
The input file is automatically released
if an EOF is encountered on input. Of
course, a SCROLL file may be used as
input with no problems.
nER Edit Read. Lines of text are transferred
from the auxiliary input file to the main
edit file. n specifies the number of
linefeeds to be transferred. Input is
inserted following the current line.
nERP Edit Read Pages. Pages of text are
transferred. This command may also be
stopped by striking a key as above.
nES Edit Skip. Behaves exactly the same as
ER except that the input is ignored.
This command is used for positioning the
auxiliary input file.
nESP Edit Skip Pages. Analogous to ERP.
With the use of auxiliary input and output files, one
may begin to accumulate a lot of temporary auxiliary files.
The following command allows one to delete unwanted files.
EKdev:filnam.ex Edit Kill. Deletes the file specified
from the directory on the device. The
command may be done at any time.
One may wish to list a line or several lines or pages on
the console teleprinter either for hard copy or verification.
SCROLL allows this via the Type commands.
nT Type. Type text beginning at the current
line onto the teletype. n specifies how
many lines. The text is typed out with
tabs expanded and form feeds typed as
nine line feeds. Long lines are broken
automatically.
nTP Type Page. n specifies how many pages of
text will be typed.
SCROLL-9
Text Positioning Commands
For all the positioning commands, a minus number implies
motion towards the beginning of the file. Should a typing
error cause a positioning command to run away, it may be
stopped by typing any key. Page commands stop at pages, and
line commands stop at lines. The key struck is ignored.
n$ $ indicates the Altmode key. If preceded by a _ _
decimal number the current line is located to the
relative line. If no number is present the command
is ignored. On an unended line (no CR/LF) 1$ is _
equivalent to CTRL/V in Text Mode and will
concatenate the line with the following line.
nP Locate to the relative page. Move forward or
backward over n form feeds. The cursor will be
located after the form feed. Minus one is assumed
for n.
/ Locate to the end of the main file. This command
is equivalent to 2047P$. _
B Locate to the beginning of the main file. This
command is equivalent to -2048P$. _
! Locate to the first line of the main file after
moving to the end first and writing out all of the
file. This comand has the same effect as EXIT
followed by an ED command reopening the file for
editing. It is much faster than B if you are past
the middle of the file.
nJ Jump the cursor n places forward or backward. J
has the same effect as n CTRL/A's or CTRL/Q's typed
in text mode. Note the anomaly when moving across
line feeds and form feeds still applies. 1 Is
assumed for n.
F Place the cursor at the front of the current line.
If the cursor is at the start of the current line,
the cursor will be placed at the start of the
previous line. The command is exactly the same as
the CTRL/F keyboard command.
H Home the cursor. Move the cursor to the home
position. The home position of the current line is
the end of it. Similiar to CTRL/H.
V KBSCRL only- Verify the current line. Echo the
current line and mark the cursor position with an
uparrow (^).
SCROLL-10
Text Deletion Commands
The text deletion commands are summarized below. These
commands permit deletion of single characters, groups of
adjacent characters, single lines, groups of lines, pages, or
groups of pages.
nD Delete n lines forward or backward. The cursor is
homed first so that forward deletion will not
delete the current line and backward will. Minus
one is assumed so that D alone will delete the
current line.
nDP Delete from the current line forward or backward
until the nth formfeed is encountered. Be careful
to insert an Altmode between the D and P if you
intend to delete n lines and move backward one
page. Carelessness may result in disaster. Minus
one is assumed for n so that DP alone will delete
back to the previous form feed (or the beginning if
no form feed is found).
U Acts exactly as CTRL/U typed from the keyboard.
Deletes all characters to the left of the cursor up
to but not including a line feed or form feed.
This is not the same as a D command since D homes
the cursor first.
nW Withdraw. Deletes n characters to the left of the
cursor. n must be positive.
In addition, the file command KILL deletes the entire
main edit file.
SCROLL-11
Text String Commands
SCROLL has a wide set of string commands. Commands are
available to search for text strings, replace the targets of
search commands, and insert text into the main file.
String search commands search for an arbitrary text
string in the main file. The cursor is placed at the end of
the string on successful completion of the command. The
target string must exist on a single line to be found. It
may not be split between lines. Carriage return, line feed
and form feed may be used in the search string but the string
will not be found unless the carriage return, CR/LF
combination, or form feed are the last characters of the
string.
The search string is entered immediately after the
search command character and is ended by an Altmode. If the
Altmode immediately follows the search command character, the
previous search string is used. The numeric argument is used
to specify the occurrence count for the search. It specifies
which occurrence of the target string will stop the search.
One is assumed so that the search will stop at the first
occurrence. If the search string specified is too long, an
SS error message is printed and the command line is
terminated. The maximum length for the search string is 16
characters. Before backward searches are begun the cursor is
backed up the number of characters plus one more than the
length of the search string. Before forward searches, the
cursor is moved forward one character. This is done so that
each search command will find the next occurrence of the
string in the specified direction.
Runaway searches may be stopped by typing any character.
The character is ignored and the search stops at the end of a
line. S and _ (backarrow, SHIFT/O) searches stop at form
feed characters encountered in the main file. This allows
the user to break a very large file into smaller pieces for
more convenient editing. In this way searches that fail
because of typing errors or because the target string does
not exist in the file, may be stopped within a short distance
of where they were started.
The Insert and Replace commands allow the insertion of
characters into the main file which cannot be typed directly
into the file via Text Mode. For instance, CTRL/Z can not be
typed in Text Mode since it is intercepted as a keyboard
command to continue a search. CTRL/Z in the file marks the
end of the file. It is displayed as a block of dots as are
many of the other CTRL characters. If it is entered into the
text and subsequently moved backwards off of the scope, the
remainder of the file becomes forever inaccessable to SCROLL.
This is a clean way to cut a file short.
SCROLL-12
nSstring$ Search forward from the current cursor _
position for the search string. Stop if a
form feed is encountered.
n_string$ (Backarrow - SHIFT/O) Search backward from the _
current cursor position for the search string.
Stop if a form feed is encountered.
nZstring$ Search forward from the current cursor _
position for the search string. Stop only at
the end of the file.
n^string$ (Uparrow - SHIFT/N) Search backwards from the _
current cursor postion for the search string.
Stop only at the beginning of the file.
Istring$ Insert the text ended by an Altmode into the _
main file. Auto tab insertion is used if it
is enabled. If the Altmode immediately
follows the I, no text is inserted.
Gterminator$ Special text insertion mode for all normal or _
control characters. The character immediately
following the G is interpreted as the
terminator. After the text has been entered,
type the terminator to end special insertion
mode.
nRstring$ Replace the argument of the last search by the _
following string. n may be specified. If n
is a positive non-zero number, then n
characters are deleted to the left of the
cursor position. If n is zero or not
specified, the number of characters in the
last search argument are deleted. R is
followed by a text string just as is I and
behaves as does I.
SCROLL-13
X Buffer Commands
The X Buffer is an area of storage which is used as a
temporary text buffer. Lines or pages of text may be
transferred to the X Buffer and the contents of the X Buffer
may be transferred back to the main file at any point. There
is a provision for transferring the X Buffer many times in
sequence into the main file. The X Buffer will hold
approximately 900 characters or roughly 30 average lines of
code. To yank a long string into the middle of a line use
the command Y2W$. This will delete the CR/LF at the end of _
the X Buffer and the cursor will be in the middle of the new
line.
nX Xfer. Transfer n lines of text into the X Buffer.
The numeric argument specifies the number of lines
beginning with the current line which are to be
transferred. One is assumed. n must be positive.
If the line is not ended it will be concatenated
with the following line.
nXP Xfer Pages. Transfer pages of text into the X
Buffer. Lines are transferred from the current
line to a form feed. The number of pages is
specified by n. One is assumed for n.
nY Yank. Transfer the X Buffer into the main file at
the cursor position. The numeric argument
specifies how many times to transfer the text. One
is assumed.
CTRL/X Transfers one line of text into the X Buffer while
in text mode.
CTRL/Y Transfers the contents of the X
Buffer into the main file at the cursor position
while in text mode.
SCROLL-14
Repeat Command
Any portion of a command string may be executed
repeatedly by specifying an appropriate numeric parameter and
enclosing the portion with '<' and '>'. The construction is
only legal for a single level but may be repeated on the
command line.
n< Begin an iterative command string. Any positive
number may be used as the argument in the range
1-4095.
> Terminate the iterative command string. '<' And
'>' must be paired and may not be nested.
SCROLL-15
Text Mode Commands
The following characters have the indicated function
when they are typed in Text Mode, that is, when they are not
typed into the Command Line. The KBSCRL version performs the
same functions in addition to the echo of the line or
character being modified.
Formatting Characters
CR Enters a carriage return and line feed into the
main file.
LF Always ignored in Text Mode.
Altmode Enter Command Mode.
Text Deletion
RUBOUT Delete one character except that carriage return is
deleted with a line feed when the line feed is
deleted at the end of a line. KBSCRL echoes the
character deleted.
CTRL/U Delete text to the left of the cursor up to but not
including the CR/LF combination. KBSCRL echoes the
new current line.
CTRL/R Delete text to the right of the cursor on the
current line including the CR/LF combination.
KBSCRL echoes the new current line.
CTRL/O Delete the tab at the beginning of the current line
if there is one and home the cursor. CTRL/O will
delete the tab inserted by the auto tabbing feature
of SCROLL. KBSCRL echoes the new current line.
Cursor Positioning
CTRL/F Move the cursor to the front of the current line.
The cursor will be just after the line feed or form
feed of the previous line. If the cursor is at the
beginning of the current line when the command is
given, it will be placed at the beginning of the
previous line. KBSCRL echoes the new current line
and marks the cursor position with an uparrow.
CTRL/H Move the cursor to the home position, that is, to
the end of the current line. If the line is ended,
the cursor will be displayed on the next line. If
the current line is not ended, the cursor will be
SCROLL-16
displayed at the end of it. KBSCRL echoes the new
current line and marks the cursor position with an
uparrow.
CTRL/A Move the cursor forward one character. If the
cursor is in the home position of the line, the
next line is brought onto the scope but the cursor
position is not changed. The cursor is still
positioned after the line feed or form feed of the
previous line. CTRL/A and CTRL/Q will not move off
an unended line. The line must be ended by a line
feed or form feed. KBSCRL echoes the character the
cursor passed over.
CTRL/Q Move the cursor backward one character. If the
cursor is at the beginning of the current line,
that is, immediately after the line feed or form
feed ending the previous line, then the current
line is removed from the scope and the cursor is at
the home position of the previous line. Note that
the cursor has not moved with repect to that line.
KBSCRL echoes the character the cursor passed over.
CTRL/W Move back one line. (Prohibited on an unended
line). KBSCRL echoes the new current line.
CTRL/S Move forward one line. (Prohibited on an unended
line). KBSCRL echoes the new current line.
CTRL/V Move forward one line whether the current line is
ended or not. This command allows concatenation of
the current line and the next line. KBSCRL echoes
the new current line.
CTRL/G Move forward one page only if the current line is
ended. A page delimiter is defined as a form feed.
CTRL/P Move backward a page only if the current line is
ended. A page delimiter is defined as a form feed.
Search and Macro
CTRL/Z Continue the last text string search in the forward
direction. If unsuccessful, the search will stop
at a form feed.
CTRL/N Continue the last text string search in the
backward direction. Continued searches always stop
at form feed characters in the main file.
Underline is backarrow on most TTYs.
SCROLL-17
CTRL/C Execute the last command line again.
I/O Switches
CTRL/T Change the state of the auto tab insertion triflop.
The auto tab mode initially assumed depends on the
main file extension. The three auto tab modes
available are for assembler files, FORTRAN or BASIC
files, and files with no tabs.
CTRL/E Advance the state of the echo tri-flop. (No echo -
Command Line echo - Full echo). In no echo mode,
no characters are echoed on the teletype. In
Command Line echo mode, the Command Line is typed
on the teletype just before it is executed. This
allows the user to check the arguments of text
string searches and the names of files opened.
Dollar signs ($) are printed for Altmodes. In full
echo mode, all characters typed into the text are
echoed. Command echo is also in effect. In
KBSCRL, this command is not available.
CTRL/D Controls the display of certain characters.
Normally tabs are displayed by positioning the
characters following them at the next 8-column tab
stop. CTRL/D causes them to be displayed as a
distinctive underline character as they are
displayed in the Command Line. Carriage returns
are display as a left pointing down arrow as they
are in the Command Line. CTRL/D is a complementing
switch. In KBSCRL, all control codes are displayed
as "^alpha" construction. Example: CR ^M, LF ^J,
FF ^L, TAB ^I
CTRL/B Display the most recent command executed in command
mode on the command line.
CTRL/K Shift case of input characters.
SCROLL-18
The Display of SCROLL
SCROLL displays a number of lines on the scope ending
with the current line. Each line is begun with a marker (a
solid triangle) to mark it as the beginning of a line. If a
line is too long for the scope, it will automatically be
continued on the next line. No characters are inserted to
break long lines. If the current line is ended, a triangle
is displayed on the following line to signify this fact.
n# The number of lines displayed on the scope is
changed to n.
Five lines is the default value for the number of lines
displayed for assembler files (.PA and .12). For all other
files, three lines is the default value for the number of
lines displayed.
The cursor, which is the character pointer of SCROLL, is
displayed as a vertical line between two characters. This
convention indicates the function of the cursor since
insertions are always made at the cursor point between two
characters and deletions are made to the left of the cursor.
The cursor is displayed somewhere on the current line at all
times.
The cursor is implemented as a minus number or zero
indicating the number of characters back from the end of the
current line on which the cursor rests. This character is
termed the cursor character. The cursor is displayed
immediately following the cursor character. The home
position for the cursor is at the end of the current line
whether it is ended or not.
The front line position of the cursor is at the end of
the previous line. The cursor character is the line feed or
form feed of the previous line. The value of the cursor is
minus the number of characters on the current line. This
convention is the source of a small anomaly with regards to
the moving of the cursor forward or backward across lines.
There are two positions of the cursor for which the cursor
character are exactly the same. Consider that the cursor is
in the front line position. The cursor is on the line feed
or form feed of the previous line. If we move the cursor
back one position, the current line is moved off the scope
and the previous line becomes the current line. The cursor
is placed at the home position of this line and is still on
the line feed or form feed of this line. To the eye watching
the scope, this is perfectly natural. However, a problem
develops when we begin to count characters to use the J
comand to move the cursor. The same convention holds for the
J command, so we must take this into account when devising
counts for the J command. Note that there are better ways to
SCROLL-19
get where you are going than using a J command. Use a search
or an F or H or locate command. It will save a lot of
trouble.
Some special characters are displayed so that the user
can more easily interpret his file. Line feeds and form
feeds are displayed as a marker on the next line. The cursor
is displayed after this marker if it is on the line feed or
formfeed. In addition, form feeds display as a curved down
arrow, the opposite direction of the carriage return, when it
is displayed. The arrow for form feed curves to the right.
Carriage return is not displayed normally in the text. In
the Command Line, it is displayed as a curved arrow to the
left. The CTRL/D switch causes carriage return to be
displayed as the curved arrow in text also. Although SCROLL
tries to assure that a carriage return is always followed by
a line feed, by inserting line feed after carriage return and
deleting carriage return after any line feed, it is possible
by trickery with cursor commands to separate them. This will
cause no end of grief since a non-displayed carriage return
in the middle of a line will cause line termination to PIP
and PAL. CTRL/D shrinks tabs to underlines and causes the
phantom carriage returns to appear. Strike CTRL/D again and
all is normal.
Lower case characters display as such. It's a strain to
fit them in a 4x6 display matrix but with practice you will
see them. They affect the output of no standard program
there may be a problem with some editors which put rubouts
after all tabs and form feeds. If you look at a file with
SCROLL and it looks very "blocky", just copy it somewhere
with PIP and look at it. PIP should clear it up nicely.
Using SCROLL Without Display
While SCROLL is a display oriented editor it is quite
usable on machines without display. The only possible
difficulty is that the display IOT codes might be used for
other functions on the computer. To use SCROLL without
display you need only disable the display routines (using
ODT) and be sure that full echo is on. A non-displaying
SCROLL will run on any OS/8 machine.
SCROLL-20
KBSCRL Display
KBSCRL is the hard copy oriented version of the editor.
The constraints of hard copy output require modification of
the 'display' and some of the command structure of SCROLL.
One clearly cannot maintain a full display that exactly
reflects the current state of the main edit file. The
changes primarily affect the positioning commands. The
commands to move the cursor forward and backward cause an
echo of the line or character scanned rather than just moving
the cursor. Also RUBOUT, CTRL/U, and CTRL/R cause an echo.
The letter 'V' appearing on a command line functions as a
Verify and echoes the current line marking the cursor
position. At any time the current status of the file may be
examined by the Type command which echoes on the editing
terminal. For example:
$-10$11T$$
Moves the cursor back 10 lines and then echoes those 10 lines
on the terminal. Example 2:
^Q^Q^Q^Q^Q$V$$
Moves the cursor back 5 characters in the current line
echoing each and then echoes the line with an uparrow marking
the cursor position. Moving backward into the line is
usually better accomplished with a search command. For
example:
$^TAB$V$$
Searches forward for the string TAB and echoes the line on
which it is found, marking the position of the cursor with an
uparrow.
In general, text mode commands which alter the cursor
position echo text and command line commands do not echo any
text unless explicitly with Type or Verify.
An attempt is made to display all characters with
control characters displayed as ^ (uparrow). If the display
tabs switch is set (^D) then tabs, carriage return and line
feed characters are displayed as their ^ construction with CR
and LF having their formatting function as well. Turning the
switch off causes these characters to be displayed as
formatting functions only. The Type command does not follow
the CTRL/D switch and always outputs formatted text. The
SCROLL-21
echo triflop is inactive, full echo is always on.
There is a minor problem with rubouts on a new line. It
is necessary to delete both the carriage return and the line
feed character even though only the CR was typed. This will
likely be corrected in the next release but the code on that
page is core tight now.
There are some minor echo problems with tab characters
on input. SCROLL automatically inserts tabs for Assembler or
Fortran code if the autotab switch (^T) is set. These tabs
do not echo however because they are deleted and replaced by
a tab following the comma to designate a label. In addition,
explicit tabs echo as ^I rather than their formatting
function because frequently the formatting effect is more
confusing than helpful. The command CTRL/H can always be
used to display the current condition of the line on input
and the tabs will be presented properly.
SCROLL-22
Auto Tab Insertion
Auto tab insertion automatically formats files during
both initial entry and subsequent editing. The mode of
insertion depends upon the state of the auto tab triflop.
The three states of this triflop are assembler file auto
tabs, FORTRAN or BASIC file auto tabs, and no auto tabs for
all other files. Initially, the auto tab triflop is set to a
mode corresponding to the type of extension in the main
filename. If the extension of the main file is .PA, .12, or
.RA, the assembler mode of the triflop is assumed. If the
extension is .FT or .BA, the compiler mode of the auto tab
triflop is assumed. For all other extensions the no auto tab
mode of the triflop is assumed. The CTRL/T command changes
the value of the triflop by sequentially stepping through the
three modes.
Auto Tab Insertion for Assembler Users
The assembler auto tab mode is assumed by SCROLL if the
main file has an extension of .PA, .12, or .RA. It saves the
programmer many key strokes per line, perhaps as many as
three or four since it inserts all tabs necessary to align
the instructions and comments of the program. We will
describe the algorithm of auto tab insertion but it is much
easier to understand its operation by watching its effects on
the scope.
The prime function of auto tabbing is to insert a tab
before every line of text as it is entered to align the
instructions of the program. If the cursor is in the home
position at the start of a new line, then a tab is inserted
before any but the following characters: CR, LF, FF, *, /,
TAB. If the cursor is at the home position and not at the
start of the line and a comma is typed, the tab at the
beginning of the line is deleted if there is one, and a comma
followed by a tab is inserted. If there is a slash or comma
on the line somewhere before the cursor position or the
character immediately before the cursor is a double quote,
the leading tab is not deleted when a comma is typed. Also,
if two or more tabs or spaces are in the current line, SCROLL
will not delete the leading tab if a comma is typed. This
allows special characters to be entered and allows RALF files
to formatted properly. Double quote is checked to avoid tab
deletion after using an ASCII constant comma (i.e. ",).
If a slash is typed and it is not the first character of
the line then enough tabs are inserted to bring the slash to
column 25. No tabs are inserted if the slash would go at
column 25. If it is entered beyond column 24, a space is
inserted before the slash. Also, no tabs are inserted if the
character before the cursor is a double quote. Note that
SCROLL-23
this presents a slight problem when using an ASCII constant
double quote followed by a comment. To avoid this problem,
enter a space after the second double quote.
CTRL/P may be used to remove the tab at the beginning of
a given line. This is generally used to place Pseudo Ops at
the left margin. Auto tab insertion is active for text mode
and for the I and R commands. It is not active for the ER
command.
Auto Tab Insertion for FORTRAN and BASIC Users
If the main file extension is .FT or .BA, the compiler
mode of the auto tab trifop is set to format FORTRAN or BASIC
files. The auto tab insertion saves the programmer many key
strokes per program. The algorithm for FORTRAN and BASIC
auto tab insertion is described below, but again, it is much
easier to understand the operation by watching its effects on
the scope.
The major function of SCROLL's compiler auto tab
insertion is to align all FORTRAN or BASIC statements after
column 7. SCROLL aligns all statements in column 8 because
of the tab which is automatically inserted. If the cursor is
in the home position at the start of a new line, then a tab
is inserted before any character except the following: the
numeric digits 0 through 9, carriage return, line feed, form
feed, and tab. A tab or a number of spaces must be inserted
after the FORTRAN or BASIC statement number is typed, in
order to get to column 7 or 8. To enter FORTRAN continuation
lines, type a space as the first character on the line.
SCROLL will tab to column 6 automatically. For FORTRAN
users, comments begin with a 'C' and have a tab inserted in
front of them. The CTRL/P function will delete the tab which
is inserted in front of the 'C', so that comments will behave
normally.
SCROLL-24
Switching from DIAL to SCROLL
A user familiar with DIAL can use SCROLL with a minimum
of effort. SCROLL is called from the OS/8 Keyboard Monitor
with ".R SCROLL". Once he is in SCROLL he should create a
file called WA.WA on the disk or system device. SCROLL will
respond initially to nothing but an Altmode because there is
no file in which to type. The command string:
$EMSYS:WA.WA[100]$$ _ __
creates a 100 block Working Area. ($ Indicates Altmode key). _
He can now use this space in the same way as DIAL's Working
Area. Files can be brought in with the EI command which is
analagous to ->AP in DIAL:
$EIFILNAM.EX$ 100ERP$$ _ _ __
will read in a file containing no more than 100 form feed
characters. There will be an error message which should be
ignored in this case. It means the input file did not have
100 edit pages, but the file was all read.
Files may be saved with the EO command which is
analogous to DIALs ->SP command. If the file does not
contain form feeds it is convenient to place one at the end,
by executing the command:
$/$$ _ __
and inserting the form feed. Now go to the beginning of the
file the fast way:
$!$$ _ __
Now save the file:
$EOFILNAM.EX$EWPEC$$ _ _ __
Will write a file with one form feed at the end onto the
device DSK:. If there is an error message, the EC command
was not performed (probably because you forgot the form feed)
and it should be done immediately:
$EC$$ _ __
If the file contains form feeds you can use a numeric
argument to ensure that it is all written:
$EOFILNAM.EX$1000EWP$$ _ _ __
In this case you are almost certain to get an error message
because there are not 1000 form feeds in the file. Ignore it
SCROLL-25
and use the EC command to close the file.
To clear the working area, use the command KILL. This
has the same function as ->CL in DIAL:
$KILL$$ _ __
The working area is now cleared for new input.
SCROLL does not use the knobs to control the display.
The keys CTRL/S and CTRL/W move the cursor forward and
backward one line respectively. The keys CTRL/A and CTRL/Q
move the cursor forward and backward one character,
respectively. These keys may be struck with the REPEAT key
held down to move the cursor faster. The command:
$n#$$ _ __
Sets the number of lines to display on the scope to n. The
command:
$/$$ _ __
Moves to the end of the file. The command:
$B$$ _ __
Moves to the beginning of the file.
RUBOUT deletes one character to the left of the cursor.
CTRL/U deletes everything to the left of the cursor on the
current line. CTRL/R deletes everything to the right of the
cursor.
To return to the Keyboard Monitor to run another
program, i.e., the assembler or another program, type:
$QUIT$$ _ __
This returns to the OS/8 Keyboard Monitor.
After your first editing session you can re-enter the
working area with:
$EDSYS:WA.WA$$ _ __
Programs left in the Working Area (file WA.WA) will be
intact.
The above commands represent a very small subset of
SCROLL's capabilities, but they serve to get you almost all
the power of DIAL. Once you are comfortable with these you
should read the full documentation again.
SCROLL-26
Helpful Hints in Using SCROLL
To position yourself in the main file, you may use the
'nP$' command to move forward n edit pages (over n form _
feeds).
Another way to position yourself is to use the 'Z'
search command. The command '$Zstring$$' will position the _ __
file after the first occurrence of 'string'.
The CTRL/C and CTRL/Z commands are useful when using the
Search and Replace commands. After the first search is made
for a symbol you wish to change, enter a Replace command
followed by a Search command with no argument. As SCROLL
stops at each occurrence of the symbol, you may visually
inspect the text. If you wish to replace the string, strike
CTRL/C; Otherwise, type CTRL/Z to continue the search from
the current cursor position.
SCROLL-27
Protecting Files
At times it may be desired to protect the main file from
modification. LOCK provides the ability to completely
inhibit insertion of text into the main file by any means.
Also all write operations on the main file are inhibited.
This saves time when examing a file. LOCK inhibits the
deletion commands also so that it is not possible to modify
the file in any way.
The LOCK command must be done when no main file is
connected with the editor. The LK error message indicates
the inability to LOCK a file once it is opened. This
restriction is enforced since when modifications are made
they must be written out to be preserved. Since LOCK
inhibits write operations, if a file were LOCKed after it
were opened the changes might not be written out. The CLOCK
command clears the LOCK condition. CLOCK may be done when a
main file is connected with SCROLL. The file then becomes
available for modification. ABORT or EXIT disconnects a main
file from SCROLL. When using the LOCK feature, ABORT is
sufficient since EXIT will cause a move to the end of the
file. Since nothing is written out this is wasted I/O time.
Note that ABORT is not sufficient after a CLOCK has been
performed. KILL does not release the main file from SCROLL
and a LOCK cannot be done after a KILL. Note that LOCK and
CLOCK must be spelled out correctly to have effect. An error
message will be printed if a mistake is made.
LOCK Lock the main file and inhibit all write
operations. Must be executed before an ED command.
(It is legal but nonsense before an EM command.)
CLOCK Clear the LOCK condition. Allows the current main
file to be modified after a LOCK.
SCROLL-28
Advanced Uses of SCROLL
The following notes may help you recover from bad
situations or at least save some time. They are rather
dangerous unless followed carefully. Novice programmers
should read them very carefully before attempting them.
Recovering Overfull Files
When you have added so much to a file that SCROLL is
unable to EXIT or finds no space at the end when it attempts
to shift the end of the file down, SCROLL's main file has
become full. No further insertions are allowed. Characters
typed from the keyboard are ignored in text mode and EDIT
Input prints an error message. The deletion commands are
still active so that you can delete enough to allow SCROLL to
EXIT. The EO command may be used to create a file to hold
the overflow text and a couple of pages may be written to the
file to allow room for SCROLL to EXIT.
There are a couple of ways to know when you have deleted
enough text. If you are in the middle of the file somewhere
and the FL error occurs during a shift operation, SCROLL will
allow you to insert text again when you have deleted an
entire block. When you are at the end, you must try to
either initialize your program with a ! or EXIT command. If
you get an EX message, you need to delete some more text.
When you have EXITed the file, you have two courses of
action. You can rebuild a single file or maintain the file
as two separate parts. The file of overflowed text may serve
as a start for a second file. Use the EI command to setup
the file to add to a new file built with EM.
Extending Files
If you are running out of room in a file and would like
to make it longer, there is a trick you may be able to play
with SCROLL to save a lot of time. If you are sure that
there is nothing beyond the file you are editing and there
are no empty files before the file which would contain the
desired file length, you may EXIT the file, and EM the same
file longer on the same device. You must immediately ABORT
this new file and reopen it with and ED command. If we are
editing a file called WORKA and would like more space, the
command:
EXIT EMWORKA[100]$ ABORT EDWORKA$$ _ __
SCROLL-29
Would lengthen the file to 100 blocks. Care must be used
with this trick or the file may be lost. If you are already
out of room, sometimes the X Buffer will hold enough text to
allow you to EXIT and remake the file longer. Put the text
in the X Buffer, then delete it from the main file. Next
extend the main file as above, then move back to where your
text belongs and Yank it back in.
If the trick cannot be used because there is a file
after it in the directory, you must create a new file with
EM. The name must be different if the device is the same.
Also if DECTAPE or LINCTAPE is used, the file should be on a
different tape. The old file should be opened for input with
an EI command. For example, the command:
EDDTA1:WORKA$ 1000ERP$$ _ __
Will read the entire file into the newly created file.
Recovering Smashed Devices
If the directory of a device gets smashed, SCROLL may be
able to help you recover ASCII files on the device. After
zeroing the directory with PIP, if it has been completely
destroyed, use SCROLL to create a file which completely fills
the device. Now immediately ABORT this file; this will allow
you to open it again for editing. Now LOCK SCROLL's edit
file and ED the file. The LOCK will assure that nothing is
written out so that it can't be changed and it will save I/O
time also. SCROLL cannot be destroyed by what it reads from
the file; the display may look very bad but that won't
matter. Begin moving forward through the file with CTRL/S
commands and watch for your lost file. If SCROLL stops it is
because it has encountered an EOF. If you remove the EOF
from SCROLL's memory, SCROLL will continue down the file as
if nothing had happened. The EOF character is 232(8) and
should be in location 13007. Use the console switches to
verify the EOF and zero that location. This is one reason
for locking the edit file. The zero you inserted will not be
written out on tape.
Locations 20 and 21 contain the block numbers that
SCROLL is looking at on the device. Locations 22 and 23
contain the block number limits of the file on the device.
You may skip around on the tape by setting locations 20 and
21 to the block numbers you would like to examine. Location
21 must be always two more than location 20 and they must
SCROLL-30
both be within the bounds of locations 22 and 23. After
changing the block numbers, moving forward or backward will
move to the new location on the tape the next time a tape
operation is done. This switching of block numbers should
only be done if the tape is LOCKed since blocks will
otherwise be written out in the wrong place.
SCROLL will not stop on EOF's in the backward direction.
A tricky thing to do to scan a whole device for lost programs
would be to open the whole device and begin scanning at the
end by setting the block numbers to the end of the file and
moving backward. Backward searches may be used to good
advantage for this.
To save a program when you have found it, open an
auxiliary file on another device using the EO command. Write
the program onto the file using the EW or EWP commands and
use the EC command to close the file. SCROLL can write out
from a locked file without problems. As many files as
desired can be written from the smashed device by repeating
the above process.
PIP and SCROLL Files
PIP may be used to help maintain SCROLL files. When
copying a file which will later be edited with SCROLL, use
the /I option of PIP to preserve the extra space at the end
of the file. The assumed /A option of PIP will allow the
user to determine the exact length of the file. PIP will
copy only the used portion of the file. The directory may
then be examined to find the exact length of the file.
There are a few problems encountered when using PIP
however. SCROLL has no restrictions on line length, so it is
possible to enter very long lines to SCROLL. PIP, however,
does not copy lines longer than 150 characters. The EO and
EW commands may be used to copy files using SCROLL. Note the
LOCK command will save I/O time during copying by eliminating
writes to the main file. Another problem is that PIP cannot
copy files larger than 255 blocks in /I mode. They must be
copied in /A mode. SCROLL edit files of this length are of
questionable use anyway. It takes over two minutes to move
from the beginning to the end of a 200 block file on
LINCtape. Even with a disk, it would take about 40 seconds.
Since SCROLL allows easy transition from one edit file to
another, it is probably better to maintain the 200 blocks in
four shorter files each of about 50 blocks.
SCROLL-31
How Do You Like Those Apples?
Well, that does it for the commands of SCROLL. Quite
impressive, isn't it? You'll probably never use EDIT-8
again, right?
We've tried to incorporate the power of the commands of
TECO into a scope oriented scrolling editor. Also we have
tried to design the commands so that the user guides the
editing process interactively without requiring that the user
repeat the commands needlessly. The CTRL/K command to
execute the Command Line again grew out of this design
effort.
The auto tabbing feature is a significant advance. The
idea first appeared in LAP6/DIAL. We have made some
improvements in the algorithm and added an indispensible
feature: the ability to turn it off!! The CTRL/P feature to
delete the tab at the beginning of the line is used primarily
to temporarily combat the efforts of the auto tab insertion
feature.
We hope that all of you enjoy using SCROLL as much as we
who developed it.
Acknowledgements
I would like to thank Clyde G. Roby, Jr., Harold L.
Pearson, Jr., Dr. Thomas W. McIntyre, and James H. Donnelly,
Jr. for their help and suggestions in the design of the
command structure for SCROLL. Clyde Roby helped with the
display routines and is responsible for the valiant work in
designing lower case pattern words in the 4x6 matrix imposed
by the PDP-12 hardware. He has also modified SCROLL to
display on a PDP-8/I with scope interface. Darrel G. Hess
wrote the original version of the summary for our local
users. Last but foremost I would like to thank Mary A.
Wilkes (Clark) and the others at Washington University, St.
Louis, for LAP6. Although the implementation of SCROLL is
entirely new, the idea is based upon earlier work we did with
LAP6. The algorithm is described in an article by Mary A.
Wilkes: 'Scroll Editing: An On-Line Algorithm for
Manipulating Long Character Strings', IEEE Transactions on
Computers, Vol C-19, pp 1009-1015, November 1970.
SCROLL-32
Chaining to SCROLL
Version 10 and later of SCROLL has the capability of
being chained to. This means that CCL can be modified to
chain to SCROLL on various recognized CCL commands, or
another program may chain to SCROLL.
In order to chain to SCROLL, the OS/8 Command Decoder
area in field 1 must be set up with legal SCROLL commands.
Multiple commands may be in this area as long as they follow
the rules of SCROLL's Command Line decoding. The Altmode
character, if present, must be 233(8). At the end of the
SCROLL Command Line in the OS/8 Command Decoder area must be
a 0000. The OS/8 Command Decoder area resides in
17600-17646.
When SCROLL is chained to, it moves the OS/8 Command
Decoder area to its internal Command Line buffer and then
executes the commands from there. SCROLL does not type out
its version number when it is chained to.
SCROLL-33
Patches to SCROLL
The six characters which are checked for in assembler
auto-tab mode and do not cause a tab to be inserted are TAB,
LINE FEED, FORM FEED, CARRIAGE RETURN, /, and *. If you wish
to have a tab inserted before the *, change location 15661
from 0252 to 0000.
Currently SCROLL puts the comment character at the third
tab stop. To change this to any other tab stop change
location 05035 to the negative of the tab stop. It is
currently 7746 which is equivalent to -32. For example, to
change this value to the fourth tab stop (42), change
location 05035 to 7736.
SCROLL is currently set up to do auto-tab insertion on
the PAL8 or PAL12 assembler syntax. This is with '/' as the
comment character and ',' as the end of tag character. To
change SCROLL to recognize other characters as comment and
end of tag syntax characters, the following locations should
be changed. This example assumes that ';' is the comment
character and ':' is the end of tag character.
.GET SYS SCROLL
.ODT
15663/0257 0273 (+) value for semicolon
15664/0254 0272 (+) value for colon
15671/0257 0273 (+) value for semicolon
^C
.SAVE SYS SCRL11
In addition, the above two patches may be separately
implemented.
SCROLL-34
Error Messages
When an error condition occurs, SCROLL types a
two-character error message and proceeds from there. If the
error occurs in a Command Line, the rest of the commands on
the line are not executed. The error messages are identified
by mnemonics which indicate the nature of the error.
In addition to the error messages which are non-fatal,
SCROLL contains many internal consistancy checks. If
something is amiss, SCROLL will halt. These errors are all
fatal and indicate either a hardware malfunction of the
computer or (less likely) a program bug in SCROLL. If the
diagnostic programs run on the computer, please convey the
halt address and conditions of failure to the author for
clarification.
If such a condition occurs, it is likely that your file
is not completely bombed out. All of the file will be in
good condition except the portion that SCROLL was working
over at the time. If you examine the file after a crash you
will find about three or four blocks are a little scrambled
or do not contain the latest changes. These blocks will be
the only ones not updated.
Error Reasons for Error
Code
ED Edit error. No such file on device or a main file
is still active.
EE No such Edit command.
EI Edit Input error. No such file or no main file.
EM Edit Make error. No room on device or main file
still active.
EO Unable to enter output file or no main file.
ER Attempt to read when no input file available.
Attempt to read more lines or pages than are in the
auxiliary input file.
EW No output file, or attempt was made to write from
past the end of main file.
EX The file is too long to EXIT. Encountered after
EXIT, QUIT, or !.
SCROLL-35
FL The last shift down found the file was full.
HA Handler allocation error. Only 3 pages are
allotted for all handlers.
IC Illegal Command Line command. A command has been
misspelled.
IE Unable to initialize (! command) when there is no
main file.
IF EOF encountered in input file or no input file.
Attempt was made to read past end of auxiliary
input file.
KI Unable to KILL. No main file.
LH Load Handler error. No such device.
LK Unable to LOCK a file once it is entered.
NE No EOF before last block encountered during shift.
NF No EOF before last block of file. Encountered
during a move.
OC Error during close of auxiliary output file.
OE No auxiliary output file.
RE Repeat error. Attempt was made to nest iteration
commands or iteration was not terminated.
SS Search string too long. 16 Characters maximum
allowed.
XC Too many characters transferred to X Buffer or EOF
in main file.
YC Unable to insert in main file by Yank command. The
file is full.
SCROLL-36
Summary of SCROLL Commands by Function
Command Lines are initialized with an Altmode and
terminated with two Altmodes. Items enclosed in square
brackets [ ] apply to the hard copy version of SCROLL
(KBSCRL)
MACRO COMMAND
****Text Mode****
CTRL/C Repeats execution of the last Command
Line.
****Command Line****
n< Initiate a repeat section of commands. n
can be any positive number in the range 0
to 4095. 1 Is assumed.
> Terminate repetitive command set. There
must be a > with every < and they may not
be nested.
FILE COMMANDS
****Command Line****
LOCK Inhibits writing to the main file. Must
be done before the Edit command.
CLOCK Clears the LOCK and enables writing.
EMdev:filnam.ex[n] Creates a file of n blocks (if n is
omitted, 10 is assumed) in length on
device DEV: with an alphanumeric name of
up to six characters and an extension of
two characters. A pre-existing file of
the same name and extension on DEV: will
be deleted.
EDdev:filnam.ex Connects the file on the given device as
SCROLL's main file.
EIdev:filnam.ex Allows reading an auxiliary input file
with ER and ERP commands.
EOdev:filnam.ex[n] Opens a tentative file which can be
written into from the file being edited.
Output is by EW and EWP. Length
specification is optional. The file must
SCROLL-37
Summary of SCROLL Commands by Function
be closed with an EC command to be made
permanent. Only one output file is
possible at a time.
EC The tentative output file is closed and
made permanent.
EKdev:filnam.ex Deletes the specified file from the
directory of device DEV:.
MAIN FILE TERMINATORS
****Command Line****
EXIT After the main file is written out on the
device, it is closed and released from
SCROLL. SCROLL awaits a new ED or EM
command.
QUIT Does an EXIT, closes any output file, and
returns to the OS/8 Keyboard Monitor.
ABORT Disconnects the main file from SCROLL
without further writing on the device.
POSITION COMMANDS
****Text Mode****
CTRL/F Move the cursor to the front of the line
[and echo the new line].
CTRL/H Move the cursor to the end of the line
[and echo the new current line].
CTRL/A Move the cursor forward one character
[and echo the character the cursor passed
over].
CTRL/Q Move the cursor backward one character
[and echo the character the cursor passed
over].
CTRL/S Move the cursor forward one line if the
current line is ended [and echo the new
current line].
CTRL/W Move the cursor back one line if the
current line is ended [and echo the new
SCROLL-38
Summary of SCROLL Commands by Function
current line].
CTRL/V Move the cursor forward one line whether
the current line is ended or not [and
echo the new current line].
CTRL/G Move forward one page in the file. A
form feed is the page delimiter.
CTRL/P Move back one page in the file. A form
feed is the page delimiter.
****Command Line****
n$ Move n lines after homing the cursor, n _
may be positive or negative. The current
line need not be ended.
nP Move over n form feeds (pages). n can be
+ or -. -1 Is assumed.
/ Move to the end of the file being edited.
B Move to the beginning of the file being
edited.
! Move to the first line of the file after
doing an EXIT.
nJ Jump the cursor n characters forward (+n)
or backward (-n). 1 Is assumed.
F Same as CTRL/F in Text Mode.
H Same as CTRL/H in Text Mode.
nES Positions the auxiliary input file to the
beginning of the n+1st line.
nESP Positions the auxiliary input file to the
beginning of the n+1st page (skipping
over n form feeds).
V KBSCRL only- [Verify the current line and
mark the cursor position with an uparrow
(^).]
SEARCH COMMANDS
****Command Line****
SCROLL-39
Summary of SCROLL Commands by Function
nSstring$ Search forward up to a form feed (end of _
page) for the nth occurrence of the
character string.
nZstring$ Search forward to the end of file for the _
nth occurrence of the character string.
n_string$ Search backward up to a form feed _
(beginning of the page) for the nth
occurrence of the character string. (_
is Backarrow, SHIFT/O).
n^string$ Search backward to the beginning of the _
file for the nth occurrence of the
character string. (^ is Uparrow,
SHIFT/N).
Rstring$ Replace the character string found by the _
last search with the character string.
nRstring$ Delete n characters to the left of the _
cursor and insert the character string.
($Sabcde$3Rx$$ gives 'abx'). _ _ __
Istring$ Insert the character string after the _
cursor.
Gterminator$ Special text insertion mode for all _
normal or control characters. The
character immediately following the G is
interpreted as the terminator. After the
text has been entered, type the
terminator to end special insertion mode.
****Text Mode****
CTRL/Z Search forward for the last search string
used. (Equivalent to $S$$). _ __
CTRL/N Search backward for the last search
string. (Equivalent to $^$$). _ __
DELETION COMMANDS
****Text Mode****
SCROLL-40
Summary of SCROLL Commands by Function
RUBOUT Delete one character to the left of the
cursor [and echo the character deleted].
CTRL/U Delete the entire line to the left of the
cursor [and echo the new current line].
CTRL/R Delete the entire line to the right of
the cursor [and echo the new current
line].
CTRL/O Delete the tab at the beginning of the
current line if there is one [and echo
the new current line].
****Command Line****
nD After homing the cursor delete n lines
forward (+n) or backward (-n). -1 Is
assumed.
nDP After homing the cursor delete backward
(-n) or forward (+n) until the nth form
feed is encountered. -1 Is assumed.
nW Delete (Withdraw) n characters to the
left of the cursor. n must be positive.
U Same as CTRL/U in Text Mode.
KILL Erases entire contents of the main file.
TEXT TRANSFER COMMANDS
****Command Line****
nEW Starting from the beginning of the
current line, write n lines of text into
the auxiliary output file. 1 Is assumed.
nEWP Starting from the beginning of the
current line, write n pages (delimited by
form feeds) to the auxiliary output file.
1 Is assumed for n.
nER After homing the cursor, read n lines
into the main file from the auxiliary
input file. 1 Is assumed for n.
nERP After homing the cursor, read n pages
(delimited by form feeds) into the main
file form the auxiliary input file. 1 Is
SCROLL-41
Summary of SCROLL Commands by Function
assumed for n.
nES Positions to the beginning of the n+1st
line of the auxiliary input file. 1 Is
assumed for n.
nESP Positions to the beginning of the n+1st
page of the auxiliary input file. 1 Is
assumed for n.
nT Type n lines on the teletype from the
beginning of the current line. 1 Is
assumed so that $T$$ prints the current _ __
line on the teletype.
nTP Type n pages (to the nth form feed) from
the beginning of the current line. 1 Is
assumed for n.
X BUFFER COMMANDS
****Command Line****
nX Transfer n lines into the X Buffer
beginning with the start of the current
line. 1 Is assumed for n.
nXP Transfer n pages into the X Buffer
starting with the beginning of the
current line. 1 Is assumed for n.
nY Transfer (Yank) the contents of the X
Buffer into the main file n times. 1 Is
assumed for n.
CTRL/X Transfer one line of text into the X
Buffer while in text mode.
CTRL/Y Transfer the contents of the X Buffer
into the main file at the cursor position
while in text mode.
DISPLAY AND SWITCH COMMANDS
****Text Mode****
CTRL/T Controls auto tab insertion.
SCROLL-42
Summary of SCROLL Commands by Function
CTRL/D Controls display of tabs and carriage
returns on the scope.
CTRL/E Controls the teletype echo. [Not active
in KBSCRL version.]
CTRL/K Shift case of input characters.
CTRL/B Display the previous command executed in
the command line.
****Command Line****
N# Controls the number of lines of text to
be displayed. n specifies this number.
SCROLL-43
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