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[*ASCI][*RUNOFF][*TITLE]DTECO %26(257) Display TECO for TOPS-10@
[*SUBTTL]Introduction@
[*BEGIN]
[*HL1]Introduction@
DTECO (Display TECO) is basically normal TECO with some special
terminal handling for such video display terminals as DEC's VT05,
VT50, VT52, or VT100. In addition, there are various "enhancements"
in DTECO such as system crash recovery which are not "display"
oriented./l
/l
In general, operation (and philosophy) of DTECO is the same as
TV on TOPS-20 systems. The major difference is that DTECO maintains
all standard TECO commands//features//quirks. DTECO extensions
(new commands//features) in some cases are the same as in TV (e.g.,
the "space" command), in some cases are similar, and other cases are
just plain different./l

[*HL1]Operation@
Basic operation of DTECO is the same as TECO (DTECO is in fact a
plug-in replacement for TECO). When first started, DTECO will read
SWITCH.INI to get and set any default processing modes desired./l
/l
Whenever started, restarted (.REENTER command), or continued
DTECO will read the terminal type from the monitor, and if the
terminal is one which DTECO recognizes (see list below) DTECO
will initiate "display" mode, otherwise DTECO simply acts like
TECO./l
/l
DTECO %26 runs in both extended and non-extended addressing environments.
In an extended addressing system (TOPS10 7.03 or later), DTECO will take
advantage of the potentially large address space available for
editing very large text files (in theory, approximately 35 million
characters maximum).

[*HL2]Screen Display Mode@
When entering display mode DTECO reads the screen width and height
from the monitor in order to figure out what size display image
to build. If the height ("page size") is 0 then DTECO will default
to the standard size for that terminal type (see list below)./l
/l
In display mode the top 10//12's of the screen is used as a "window"
into the text (edit) buffer and the remainder of the screen is devoted
to user command typein. The logical text cursor (".") is displayed on
the screen as a slash character followed by a backslash character
(like so: ///\). Normal text characters appear as themselves, and most
control characters appear in up-arrow form (Control-A for example
would appear as ^A). Tabs appear as blank space on the screen (a
tab stop is set every 8 character positions). Carriage return-line
feed pairs appear as themselves (i.e., a new display line starts).
A stand/-alone carriage return appears as ^M. A stand/-alone line feed
appears as ^J and starts a new display line with leading space fill
(i.e., the next screen character starts one line below the ^J
without going back to the left margin). Vertical tabs and form feeds
appear as ^K and ^L respectively and start a new display line at the
left margin. RUBOUTs appear as ^?. A line of text which exceeds the
page width will be continued on the next line with a vertical bar
or similar character (exclamation point usually, depending on
the terminal type's usual character set)
character being displayed at the right margin of each line which
overflows into the next display line./l
/l
Normally, when in display mode, DTECO will redisplay the text
buffer after the completion of a command string (i.e., when DTECO
prompts you for a new command). If, however, an error occurred in
the execution of the command string (such as a search failure) or
"program" output has appeared (such as from a "=" or "^A"
command) such that the screen has been scrolled (in particular,
such that the text window has been at least partially overwritten)
then DTECO will "freeze" the screen so that the error
message (or whatever) does not get erased before you have a chance to read it.
The screen will be updated at the next command string completion
(unless of course another error/f./f./f.). When DTECO freezes the
screen the message:/L
/f/f/[TECSFT Screen "frozen" due to program typeout, ^L to refresh/]/l
will be issued to alert the user (see also the //SFT switch in 
section 6 on SWITCH.INI)./l
/l
Additionally, if DTECO notices that typein is available while
updating the display window then DTECO will abort the update and
go immediately to command input state. This is done on the premise
that the current "incomplete" command will be shortly completed and
change the screen so that any changes being output will be superseded
and therefore useless (in other words it's a hack done for speed).
This can be especially useful on slow (e.g., 300 baud dataset) lines
- although TOPS-10's willingness to buffer up terminal output tends
to nullify this "feature" more often than not./l
/l
The terminals currently recognized by DTECO are:/l
/l
[*lm]3.0@[t%][ts9.0][fu]Terminal	Default screen length[fu%]/l
/l
VT05	20/L
VT50	12/L
VT52	24/L
VT55	24/L
VT61	24/L
VT100	24/L
VT101	24/L
VT102	24/L
VT103	24/L
VT125	24/L
VT180	24/L
VT185	24/L
VT220	24/L
VT240	24/L
VK100	24/L
DAS21	24/L
[*LM]0.0@

[*HL2]Memory Usage@
With the addition of the EA command (see section 9) and the
//EAMODE SWITCH.INI switch DTECO now tends to run with a
rather large working set, with the attendant strain put upon
the system as a whole (in particular as regards swapping)./l
/l
In an attempt to be somewhat more efficient with respect to the
system as a whole, DTECO will try to shrink its editing buffer
whenever the user deletes any text from the editing buffer.
This shrink action is delayed until the completion of the second
command string after the deletion command in order to provide a
caching action in case the memory is needed again immediately
(ERCOMMON.MAC$$, search for junk, HK$$, ERDDT.MAC$$,
and so on). This shrink action is very simple minded, and in
particular does not do a general garbage collection//compaction
pass, so any Q-registers deleted will not be reclaimed.

[*hl1]Command Typein and Editing@
As with TECO, DTECO will not execute the command string until the
user types two consecutive /<ESC/>'s. Until the command string is
terminated and executed the user has the ability to "edit" the
command string.

[*NOTE]Note@Currently DTECO does not automatically wrap a command line
which exceeds the terminal//screen width. As a result the terminal
carriage//screen cursor will be left at the right margin for all
characters past the width limit, generally resulting in a "splotch"
at the end of the line. At this point the editing commands listed
below are subject to misrepresentation of the current command image.@

In the following discussion the term "blank" as used in a character
context means: 1) a space character (ASCII 40 octal); A tab character
(ASCII 11 octal); or a carriage return-line feed pair of characters
(ASCII 15 and 12 octal)./l

[*hl2]Quote Character@
The Control-V character instructs DTECO that the immediately
following command character, if not a RUBOUT, is to be treated as
normal textual character input regardless of any other meaning DTECO
normally puts on the second character. If the immediately following
command character is a RUBOUT then the Control-V is deleted.

[*hl2]Delete Character@
The RUBOUT character (also labeled DELETE, DEL, RUB CHAR, and even
Control-? (yes, that's ^?)) unconditionally deletes the last command
character - if any - from the command buffer./l
/l
On a hardcopy terminal the command character deleted is "echoed"
back to the terminal. When the last command character is deleted
DTECO will issue a /<CR/>/<LF/> and reprompt with another "*"./l
/l
On a display-mode terminal the command character deleted is erased
from the screen. Deleting a vertical format effector character
(line feed, vertical tab, or form feed) will move the screen cursor
up the appropriate number of screen lines. Deleting the /<LF/> of
a /<CR/>/<LF/> pair will leave the cursor at the begining of the
line (i.e., the left margin) terminated by the /<CR/>. Subsequent
deletion of the stand/-alone /<CR/> will leave the cursor at the
end of the command line./l

[*hl2]Delete Word@
The Control-W character deletes the last command "word" - if any -
from the command buffer. The exact operation of Delete Word is as
follows: 1) Any and all trailing blanks are RUBedOUT;
2) The immediately preceding non-blank character - if
any - is RUBedOUT; 3) Any and all preceding command characters up
to but EXcluding the first (going backwards) word break character
are RUBedOUT. A word break character is any character other than
a letter ("A" to "Z"; "a" to "z"), a number ("0" to "9"), or a dash
("-")./l

[*hl2]Delete Line@
The Control-U character deletes the last command line - if any -
from the command buffer. The exact operation of delete line is
as follows: 1) The immediately preceding command character - if any -
is RUBedOUT; 2) Any and all preceding command characters up to but
EXcluding the first (going backwards) line break are RUBedOUT. A
"line break" is a carriage return followed by a line feed, a vertical
tab, or a form feed (i.e., one of /<CR/>/<LF/>, /<CR/>/<VT/>, or
/<CR/>/<FF/>)./l

[*note]NOTE@The user should be cautioned that by condition "1"
above multiple ^U's will RUBOUT multiple lines. This operation is
different from TECO, where the ^U will not cross the line break
boundary@

[*hl2]Delete Sentence@
A Control-W character immediately preceded by a Control-G character
(i.e., ^G^W) deletes the last command sentence - if any - from the
command buffer. The exact operation of Delete Sentence is as
follows: 1) Any and all trailing blanks are RUBedOUT;
2) The immediately preceding non-blank character - if
any - is RUBedOUT; 3) Any and all preceding command characters up
to but EXcluding the first (going backwards) sentence break character
are RUBedOUT. A sentence break character is any character other than
a letter ("A" to "Z"; "a" to "z"), a number ("0" to "9"), a dash
("-"), or a blank./l

[*hl2]Delete Command@
A Control-U character immediately preceded by a Control-G character
(i.e., ^G^U) deletes the entire command string - if any - from the
command buffer. The exact operation of Delete Command is as follows:
Any and all command characters up to and INcluding the first command
character typed - if any - are RUBedOUT./l
/l
The deleted command string is available via the "first character
special" command "*" as in TECO./l

[*hl2]Retype Command Line@
A Control-R character causes the current command line - if any -
to be re-echoed to the command terminal. A command line is the same
as defined by Delete Line above./l
/l
On a hardcopy terminal DTECO will first issue a /<CR/>/<LF/> to get
to a new line before re-echoing the command line./l
/l
On a display terminal DTECO will first back the cursor up to the
begining of the screen representation of the command line before
re-echoing the command line./l

[*hl2]Retype Command@
A Control-R character immediately preceded by a Control-G character
(i.e., ^G^R) re-echos the entire current command string - if
any - to the terminal./l
/l
On a hardcopy terminal DTECO will first issue a /<CR/>/<LF/> to get
to a new line before re-echoing the command string./l
/l
On a display terminal DTECO will first back the cursor up to the
begining of the screen representation of the command string before
re-echoing the command string./l

[*hl2]Lower-case Shift@
The Control-A character, when encountered as part of a text string
within an insert or search command, instructs DTECO to treat the
immediately following text character as a lower-case letter./l
/l
Two successive Control-A's "lock" DTECO into lower-case text mode
wherein all subsequent text characters will be treated as lower-case
(unless otherwise shifted via Control-B commands). The lower-case
shift lock is cleared at the end of the text string./l

[*hl2]Upper-case Shift@
The Control-B character, when encountered as part of a text string
within an insert or search command, instructs DTECO to treat the
immediately following text character as an upper-case letter./l
/l
Two successive Control-B's "lock" DTECO into upper-case text mode
wherein all subsequent text characters will be treated as upper-case
(unless otherwise shifted via Control-A commands). The upper-case
shift lock is cleared at the end of the text string./l

[*hl1]EO value 3 conversion@
DTECO %26 runs with an EO value of 3, which enables the above
command typein and editing functionality. Setting the EO value
to 2 will cause ^R, ^V, and ^W to behave as in TECO %24 and earlier.
Setting the EO value to 2 does not bring back the the old ^G
commands (retype line and abort command). Following is a table
of old-to-new command conversions:/l
/l
[*lm]3.0@[t%][ts9.0][fu]Obsolete	New[fu%]/l
/l
^Gspace	^R/l
^G^G	^G^U/l
^R	^V/l
^V	^A/l
^W	^B/l
[*lm]0.0@

[*HL1]Crash Recovery@
Under control of the //CRDISP and//CRFILE switches (see section 6 below)
DTECO writes a crash recovery file called DSK:/[,/]nnnTEB.TMP/<077/>
(or /<477/> if the system is a File Daemon supporter) where
"nnn" is the leading-zeros three-digit job number running DTECO.
This crash recovery file contains every character you have typed to
DTECO since program startup (this includes chararacters you may
have deleted (both the character and the RUBOUT are in the recovery
file) and even commands aborted via ^G^U). This file is periodically
written out to disk in such a manner as to be preserved across a
system failure of all but the most catastrophic nature (such as
a disk head crash). By default the crash recovery file is updated
every 128 (decimal) characters modulo lines (i.e., at the first
"break" condition after 128 or more characters have been input), or
when a full disk block has been input./l
/l
In general crash recovery simply involves executing the crash
recovery file as a command file (the "E/@" command, see section 9
below). This will work whether DTECO was invoked via a RUN command
(or monitor call) or if DTECO was entered via the CCL mechanism
(e.g., the TECO monitor command). Remember however that the crash
recovery file is written into your job's logged-in ppn (directory),
not the current path!/l

[*NOTE]*** Warning ***@Care must be exercised in executing the
crash recovery file if one or more output files have already been
written - since the entire command stream is still present in the
crash recovery file the already-written output files will be
written again. If the already-output files were the result of
editing extant files (e.g., the "EB" command) executing the crash
recovery file will re-edit the already-edited files, to the
extreme detriment of the file(s) in question./l
/l
Further consideration must also be given to ensure that the
job's path, search list, and logical name definitions match those
used by the previous editing session which wrote the crash recovery
file./l@

Upon normal program termination (e.g., the "EX" command) the
crash recovery file will normally be deleted./l

[*HL1]SWITCH.INI@
DTECO supports SWITCH.INI default processing as defined by SCAN.
If DSK:SWITCH.INI/[,/] exists then DTECO will read and process the
file looking for entries under "TECO". There is no provision currently
for specifying an specific option (i.e., the //OPTION:option
switch to SCAN)./l

[*HL2]//CRDISP:(NEVER|TEMPORARY|DELETE|PRESERVE)@The //CRDISP switch controls
whether or not DTECO will create a crash recovery command file, and
if so, whether or not that crash recovery file will be automatically
deleted when DTECO exits. //CRDISP:NEVER instructs DTECO to not
write a crash recovery file; //CRDISP:TEMPORARY instructs DTECO to write
the crash recovery file with extension .TMP (so LOGOUT can delete it)
and delete it when the editing session is over;
//CRDISP:DELETE instructs DTECO to write the crash recovery file
with extension .TEB (so LOGOUT won't delete it) and delete it
when the editing session is
over; //CRDISP:PRESERVE instructs DTECO to write the
crash recovery file with extension .TEB and keep it when the
editing session is over.
The default is //CRDISP:TEMPORARY./l

[*hl2]//CRFILE:file@The //CRFILE switch is used to explictly name
the crash recovery file. By default, DTECO calls the crash recovery
file DSK:nnnTEB.TMP/[,/]. The //CRFILE switch accepts a file specification
which may include any of device, filename, extension (or type), or
directory path. Explicitly specifying a filename is MOST STRONGLY
discouraged since multiple users will interfere with each-other.
The primary intent of the //CRFILE switch is to allow users to specify
whether the crash recovery file gets put in the user's logged-in
ppn (/[,/]) or default path (/[-/]). Wildcards are not allowed in
the file specification, nor may file-specific switches (e.g.,
//PHYSICAL or //PROT:nnn) be used./l

[*hl2]//CRPROT:nnn@The //CRPROT switch is used to specify an
explicit protection code for the crash recovery file. Normally
DTECO will protect the file /<077/> if the system does not have
File Daemon support, or /<477/> is the system does have File
Daemon support./l

[*HL2]//CRSAVE:nnn@The //CRSAVE switch is used to control how often
the crash recovery file is updated. The value "nnn" is the count of
characters "modulo" lines which will trigger an update of the
crash recovery file. If "nnn" is 0 (or very large - greater than
637 decimal) then the crash recovery file will be updated only
when a full disk block's worth of characters have been received
(without respect to line boundries)./l

[*hl2]//EAMODE@The //EAMODE switch controls whether or not DTECO
will attempt to read in the entire file (see the "EA" command in
section 9 below for details) automatically upon execution of
an "ER" or "EB" command. //EAMODE (or //EAMODE:ON) instructs
DTECO to attempt to read the entire file into the editing buffer;
//NOEAMODE (or //EAMODE:OFF) instructs DTECO to read the input
file in pieces as needed (the default)./l

[*hl2]//EOBATC:n@The //EOBATCh switch is used to specify the
default EO value if DTECO is running as a batch job rather than
as a timesharing job. If //EOBATC is not specified then //EOMODE
will be used - if given./l

[*hl2]//EOMODE:n@The //EOMODE switch is used to specify the
default EO value if DTECO is running as a timesharing job rather
than as a batch job./l

[*hl2]//INITFILE:file@The //INITFILE switch is used to specify
an initial command file which DTECO will execute before any other
user commands (including CCL processing) are processed. The
form is //INITFILE:file where "file" is a simple file specification
(no wildcards, no switches) of the file which is to be "executed"
as a command file./l

[*hl2]//OKLSN@The //OKLSN switch controls whether or not DTECO
will process (and by default preserve) embedded line sequence numbers
in input files read under //EAMODE:ON. //OKLSN (or //OKLSN:ON)
instructs DTECO not to bother looking for line sequence numbers
in the input file; //NOOKLSN (or //OKLSN:OFF) instructs DTECO to
scan the input file looking for possible line sequence numbers
(the default)./l

[*hl2]//OKNULL@The //OKNULL switch controls whether or not DTECO
will process (and by default discard) nulls in input files read
under //EAMODE:ON. //OKNULL (or //OKNULL:ON) instructs DTECO not
to bother looking for nulls in the input file; //NOOKNULL (or
//OKNULL:OFF) instructs DTECO to scan the input file looking for
possible embedded nulls (the default)./l

[*hl2]///[NO/]SFT@The ///[NO/]SFT switch controls whether or not
DTECO will issue the TECSFT message whenever the display screen
is frozen due to program typeout. //SFT enables the TECSFT message
output. //NOSFT suppresses the TECSFT message output.
The default is //SFT.

[*hl2]//RUN:file@The //RUN switch instructs DTECO to pass program
control to another program rather than to the monitor when DTECO
"exits". If //RUN is specified in SWITCH.INI then DTECO will not
exit with an output file OPEN, or with text present in the editing
buffer (see the Control-Z command below).

[*HL1]Searches@
DTECO now has faster, backwards, and//or bounded searching
capability./l
/l
If a search command (e.g., "S", "FN", "FD", etc.) is preceded
by a single negative argument then the search procedes backwards
from "." towards "B" rather than forwards towards "Z". At the
successful completion of a backwards search "." is left at the
begining of the matched string rather than at the end. This is
to allow successive backwards searches to find the "next"
string, rather than rematching the just found string again./l
/l
If a search command is preceded by two numeric arguments then
the search is a "bounded" search where the two arguments define
the begining and ending limits of the search. If the first argument
is less than the second argument then the search is a normal forwards
search; if the first argument is greater than the second argument
then the search is a backwards search./l
/l
When a search fails, "." is left unchanged, rather than at "B" 
in the text buffer. If the failed search caused I//O (e.g.,
an "_" or "N" search) then "." is left at the begining of
the text buffer as usual.

[*hl1]First-Character-Special Commands@
"First-character-special" commands are a special class of commands
which, iff typed as the FIRST command character (i.e., the
first character typed after DTECO prompts for input with its "*"),
are interpreted differently than if they were encountered within
a regular command string. An example of this is the old "*" command
used to load a q-register with the last command string when typed
as the first character of a command, but means multiplication
if encountered in a normal command string terminated by two
/<ESC/>s./l

[*hl2]The "Arrow" Keys@Some terminals (in particular, VT05's,
VT52's, and VT100's) have keys marked with an arrow (Up-, Down-,
Right-, and Left-pointing). DTECO will interpret these keys as
cursor-moving (i.e., moving ".") commands. The "Up" key will
move "." one screen line upwards; the "Down" key will move "."
one screen line downwards; the "Right" key will move "." one
text character to the right; and the "Left" key will move "."
one text character to the left./l
/l
The "Up" and "Down" keys are quite distinct from the regular "L"
command in that they will move "." based on the editing-text's
screen representation, NOT on the placement of break characters
within the editing text (and in particular, the "Down" key and
the "Line feed" command are quite distinct and behave differently).

[*NOTE]NOTE@Some terminals (notably VT05's) send control characters
for the arrow keys. These control characters may conflict with
other first-character-special commands. When a conflict arises, the
arrow meaning takes precedence over any other meaning, so long as
the character gets to DTECO (if a terminal sends a Control-C then
all bets are off).@

[*hl2]Space@The space command (i.e., the space character)
will, iff in display mode, cause DTECO to display the next screenful
of text from the edit buffer. The space command is in effect an easy
way of scrolling through the edit buffer. Execution of the next
regular command string will redisplay the screen such that "." is
on the screen, if it isn't already there./l

[*hl2]Backspace@The backspace command (Control-H) will,
iff in display mode, cause DTECO to display the previous screenful
of text from the edit buffer. The backspace command is in effect
an easy way of scrolling backwards through the edit buffer. Execution
of the next regular command string will redisplay the screen such
that "." is on the screen, if it isn't already there./l
[*NOTE]NOTE@On a VT05 terminal the "Left" key transmits a
Control-H character, which is interpreted as a "Left" command
rather than as a "backspace screen" command.@

[*hl2]Carriage return@The carriage return command will, iff in display
mode, cause DTECO to move the cursor (".") such that it is contained
within the current display window. If "." is already within the display
window the carriage return command will position "." to the begining
of the screen line containing "."./l
/l
One oddity of the carriage return command is that execution of the
command /[from the top-level command terminal/]
will result in an explicit "nnnJ$$" command appearing in the
crash recovery file immediately following the carriage return. This
will ensure that, should the crash recovery file be executed on a
different terminal type (in particular, one with a different screen size),
all subsequent commands (such as a "D" command) will be executed in
the right place within the text./l

[*hl2]Line feed@The line feed command will move "." to the begining
of the next line (e.g., a "1L$$" command) as defined by the presence
of a break character in the text buffer, not as displayed on the
screen (if any). If, in addition, DTECO is not in display mode the
line will be typed out (e.g., the line feed is equivilent to a "1LT$$"
command)./l

[*hl2]Form feed@The form feed command will, iff in display mode,
cause DTECO to immediately refresh the display screen./l

[*hl2]^Z@The Control-Z character is the same as the Control-Z command
(see the Control-Z command below).
[*NOTE]NOTE@On a VT05 terminal, the "Up" key transmits a
Control-Z character, which is interpreted as an "Up" command
rather than as a Control-Z command.@

[*hl1]Regular Commands@
"Regular commands" are simply normal TECO commands typed in but not
executed until the final terminating double /<ESC/> is seen./l

[*hl2]$$ - The null command@To DTECO the null command (a degenerate
case of regular commands) does in fact have some effects./l
/l
The first effect is that the crash recovery file is forcably (and
prematurely) updated. This can be useful if you plan on being away
from your terminal for a while but don't wish to terminate the
editing session yet. Typing "$$" will ensure that, should the system
crash while you are (e.g.,) eating lunch, no editing will be lost./l
/l
The second effect is that the screen will be updated such that "."
is guaranteed to be contained within the current display window. This
effect is useful if an error message has frozen the screen./l

[*hl2]^Z - EXit@The Control-Z command is used to effect an
immediate and non-destructive return to monitor level. The
Control-Z command does not perform any file I//O - and in
particular does not CLOSE the editing file. DTECO will immediately
update the crash recovery file however./l
/l
If no //RUN was specified in SWITCH.INI then a Control-Z command
always returns to monitor level. If there is an output file
OPEN then the message:/l
/f/f%TECOFO Output file still OPEN, type CONTINUE then "EX$$" to write it/l
to warn the user of possible lossage. If there is no output file
OPENed, but there is text in the editing buffer then DTECO
will issue the message:/l
/f/f/[TECNFO No file for output/]/l
to warn the user. If there is no output file OPENed and no text
in the editing buffer then DTECO simply returns to monitor
level./l
/l
If //RUN was specified in SWITCH.INI then a Control-Z command
will transfer control to the specified program iff there is
no possible damage to the editing session. If there is an
output file OPEN then DTECO will issue the message:/l
/f/f?TECOFZ Output file still OPEN, type "EX$$" to exit/l
to warn the user, and return to DTECO command input state.
If there is no output file OPENed, but there is text in
the editing buffer then the message:/l
/f/f?TECNFZ No file for output/l
will be issued to warn the user, and DTECO will return to 
command input state. If there is no output file OPENed and no text
in the editing buffer then DTECO will RUN the specified program./l
/l
The user can always type the CONTINUE monitor command to resume
the editing session after DTECO has returned to monitor level
in response to a ^Z command. DTECO is not responsible for
the results of any foolish command such as FINISH or CORE 0.

[*hl2]E-atsign - Execute command file@The "E/@" command is used to tell
DTECO to execute a command file. The format of the command is
"E/@file//switch" where "file" is a normal file specification and
"//switch" is one of "//TYO" or "//ECHO". The default device is
DSK:, the default extension (file type) is .TEC, the default file
path is /[-/]./l
/l
A command file is simply a file which contains 7-bit ASCII characters
which DTECO will interpret as commands EXACTLY as if they were being
input from the command terminal (with the exception of carriage
returns - see section 8.4). For example,
if the first character of a command
string is a space then DTECO will display the next screenful of text
(within the outputing constraints described below)./l
/l
Normally DTECO will suppress all display window output when executing
a command file ("program" output (e.g., "^A" or "=" commands) and
error messages are not suppressed). The //TYO switch (a poor name I
will admit, but I couldn't think of anything better on the spur of
the moment) instructs DTECO to output all normal display window output
(which includes the "*" prompt by the way). The //ECHO switch
instructs DTECO to not only output all normal display window output but
"echo" the command file "typein" as well. (//ECHOing a crash recovery
file can be a very sobering experience as you watch all the
mistakes you made go flashing hauntingly by/f./f./f.)/l
/l
If the top level command file terminates with a partially input command
string (i.e., a command string but no terminating double /<ESC/> yet) a
warning message will be issued:/l
/f/f%TECEOC End of command file with unterminated commands pending/L
/l
Execution of a command file does not begin until the current command
(the one which caused an "E/@" command to be executed) is finished. For
example, the command string "E/@BLAH$4L$$" will execute the "4L" command
before reading the first command file character from "DSK:BLAH.TEC/[-/]"./l
/l
Command files can, of course, be nested./l

[*hl2]EA - Edit All (or Edit Append)@The "EA" command is both a
status-setting command and an action command, depending on the
arguments typed. The basic format of the "EA" command is "nEA"./l
/l
If "n" is absent (e.g., "EA$$") then DTECO will attempt to read
the entire input file into the text buffer, using, if possible,
dump mode I//O to read the file directly into the editing buffer.
Unless explicitly prevented by switches in SWITCH.INI DTECO will
scan the file looking for embedded nulls and//or line sequence
numbers./l
/l
If "n" if positive then DTECO will perform "n" appends, preserving
form feeds as text characters./l
/l
If "n" is "0" then DTECO will clear the "EA-by-default" flag. If
"n" is "-1" then DTECO will set the "EA-by-default" flag. The
"EA-by-default" flag (also set//cleared via //EAMODE in SWITCH.INI),
if set, instructs DTECO to automatically try to read the entire
input file whenever a new input file is given ("ER" or "EB"
command)./l

[*hl2]EC - Edit Close@The "EC" command instructs DTECO
to write out the current text buffer, copy any remaining input file
to the output file, and close the output file. The "EC" command is
essentially an "EX" command which returns to DTECO command mode
rather than to monitor command mode. If possible, the text buffer
will be written using dump mode for speed (KL-10's can "dump" almost
1000 blocks per second!)./l

[*HL2]FD - Find and Delete@The "FD" command is used to find and
delete a text string. The command format is "FDstr$" where "str"
is the text string to be deleted. As with other searches, the
"FD" command may be colon and//or atsign modified.

[*hl2]FK - Find and Kill@The "FK" command is used to find and kill
text up to and including a text string. The command format is
"FKstr$" where "str" is the text string to be searched for. All
text from current "." to and including the matched text string
is deleted when a match is found. As with other searches, the
"FK" command may be colon and//or atsign modified.

[*hl2]FR - Replace@The "FR" command is used to replace the last
string with a new string. The command format is "FRstr$" where
"str" is the new text string. The "FR" command is essentially
equivilent to a "-nDIstr$" command where "n" is the size of the
last string operation (such as a successul search, an insert,
or a Q-register text operation). The "FR" command has no
positional information, if "." has been moved since the last
string operation then the string replaced will not be the last
string affected.

[*hl2]F_ - Find and Replace@The "F_" command is to the "_" command
as the "FS" command is to the "S" command.

[*hl2]/\/\ - Octal "/\"@The "\\" command is just an octal mode "\"
command, just like the "==" command is an octal "=" command./l

[*hl2]V - View Text@The "V" command is used to view text from the
text buffer. If DTECO is not running in display mode the "V"
command is identical to the "T" command./l
/l
If DTECO is running in display mode there are 2 forms of the "V"
command. The first format is "nV". This command "shifts" the display
window by "n" display lines (not text lines). The second format is
"i,jV". This command sets explictly the start and the ultimate end
of the display window to "i" and "j" respectively.
[*note]WARNING@The "V" command is almost certainly going to be
changed in future versions of DTECO, so do not get too used to
the current syntax!@

[*hl2]FV@The "FV" command returns as a value the negative length
of the last text operation such as a search, insert, or "G" command.
If the search was in backwards mode, then the "negative" length will
be a positive value, such that an "FVC" command will always position
"." to the 'other' end of the string, "FRstr$" will always replace
the matched string, and so on.

[*hl2]EP - Edit Push@The "EP" command instructs DTECO to "PUSH" to
a new job command context, much like the monitor "PUSH" command.
The "EP" command takes no arguments presently, but does require a
terminating /<ESC/> character (e.g., "EP$") to allow for future
compatible expansion.
[*NOTE]NOTE@All characters between the "EP" command and the
terminating /<ESC/> character are eaten and discarded. They have
not semantic interpretation yet.@
When the new context "POP"s back, DTECO resumes command execution.

[*hl2]% - Increment Q-Register@The "%" command has been enhanced to
accept a preceeding argument. If an argument is provided, the argument
is used as the quantity to be added to the specified Q-Register. If
no argument is provided, then "1" is  added to the Q-Register.
If the "EO" value is less than "3" then the argument is always
ignored and "1" is always assumed.

[*hl2]^T - Typein//out@The ^T command has been enhanced to accept
a preceeding argument. If an argument is provided then ^T will type
that argument as an ASCII character (e.g., ^O101^T would type a
capital "A"). If the argument is omitted, then ^T will accept and
return the value of one command input character. If the "EO" value
is less than "3" then the argument is always ignored and typein is
always assumed.

[*hl1]Known Bugs, Deficiencies, and other undesirable Aspects@
Following is a list of problems known to exist with DTECO. Some are
admittedly out and out bugs, others are more in the line of simple
deficiencies, and some are expressions of the undesirable vagaries
of reality beyond DTECO's immediate control./l

[*hl2]Command deletion (RUBOUTs and ^Us)@
There are two cases where the screen logic of DTECO fails to correctly
(or at least "nicely") handle RUBOUTs and//or ^Us. If a command line
exceeds the screen width a free /<CR/>/<LF/> is not issued - the cursor
is left splattered against the terminal's right margin. At this point,
RUBOUTs will start eating backwards, erasing characters which have
not yet been deleted from DTECO's command buffer (DTECO effectively
thinks the right margin is at infinity/f./f./f.). Once the cursor has
been backed into the left margin it will sit there vainly trying to
erase more characters until the entire line is erased./l
/l
The second case is basically of the same genre, only more so! This is
the case of RUBOUTs going off the top of the screen - it would be nice
if DTECO would automatically retype part of the command text so the
user had a better idea of what was happening./l

[*hl2]Screen formatting, ^O, and "SEND" messages@
The Control-O character echos with a free /<CR/>/<LF/> and is not passed
to the user program. Thus typing a ^O will move the cursor down on the
screen without telling DTECO that the cursor moved. DTECO may thus
become confused and update the wrong portion of the screen. If this
happens, force a screen refresh (see form feed command in section 5.1.5
above) to get things in sync again./l
/l
Similarly, being the receipiant of a SEND message, or any type of
"unsolicited" terminal output, will generally trash some part of the
screen./l

[*hl2]The "V" command@
Some of the more involved uses of the "V" command may leave much to
be desired in so far as screen output is concerned (try "1V1V1V$$"
for example)./l

[*hl2]^C and malicious users@
Command sequences such as ^C, .FIN, .CONT lose./l

[*hl2]Overall speed@
There are many known ways in which DTECO could be sped up, such as
in inserting and deleting characters.
Maybe someday (I'm always open to a bribe/f./f./f.)./l

[*hl2]Halts@
DTECO %26(257) should not by any means be considered a final
polished product (as witness this section's raison d'etre). There
are a variety of bugs (and maybe even an unknown feature or two)
lurking around, waiting to bite someone. Further, DTECO is liberally
sprinkled with debugging HALTs. Should you be
so "fortunate" as to discover a way of exercising one of these little
gems please make a copy of the nnnTEB.TMP file as well as the input
file (if any) being edited and let me know about them./l
/l
In general, you can try to "CONTINUE" from the HALT - it might
even work./l

[*hl1]Afterword@
This product is not an official undertaking. It did not enjoy the
benefits of careful design review boards. It does not even have a
functional spec (execpt insofar as what is "obviously right")!/l
/l
As such, any and all extensions over what DEC-standard TECO provides
should be considered as somewhat "volatile" and subject to change
at a moments whim, I mean, ah, notice./l

[*END]