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APPENDIX D
OS/8 OPERATING CHARACERISTICS
D.1 Startup
TECO is started with the
.R TECO
command. TECO is now immediately ready to accept commands. The
text buffer and Q-register areas are empty.
The TECO command
.TECO filespec
is used to edit an already existing file. It is equivalent to
.R TECO
*EBfilespec$Y$$
OS/8 "remembers" the filespec as the name of the last file that
has been edited.
The MAKE command
.MAKE filespec
is used to create a new file. It is equivalent to
.R TECO
*EWfilespec$$
OS/8 "remembers" the filespec as the name of the last file that
was edited.
The command
.TECO filespec1=filespec2
is used to edit filespec2 into filespec1. That is, filespec2 is
opened as the input file, and filespec1 is created as the output
file. It is equivalent to
.R TECO
*ERfilespec2$EWfilespec1$Y$$
OS/8 "remembers" the fielspec1 as the name of the last file that
was edited.
The command
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.TECO
with no arguments, causes CCL to execute the command
.TECO filespec
where filespec was the file that was previously remembered as the
last file to be edited. The system purposely does not remember
filenames from one day to the next, but it will remember names
across bootstraps.
The command
.MUNG filespec
executes the specified TECO program. The default extension is
.TEC . This is equivalent to the sequence:
.R TECO
*ERfilespec$YHXYHKMY$$
Another format of this command is
.MUNG filespec,argument
which is used to pass an argument to the TECO program to control
its action. This is equivalent to the sequence:
.R TECO
*ERfilespec$YHXYHKIargument$MY$$
The argument may be the name of a file that the TECO program
is to mung, or it may be a command to the program to specify what
action to take, or whatever. It is up to the TECO program to
decode this argument (which is left in the text buffer) and take
appropriate action. A TECO program executed via the MUNG command
must never destroy the text storage area of Q-register Y and
expect to ever see the light of day again.
Note the input file remains open and can provide more input to
the macro.
D.2 Startup Conditions
The initial value of the EU flag is 0 if the CCL command SET
TTY NO SCOPE had been previously issued, and is -1 if the CCL
command SET TTY SCOPE had previously been issued.
The initial value of the ET flag is as follows:
Bit value Initial value
1 0
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2 0 (1 if terminal is a scope)
4 0
8 0
16 0
32 0
64 0
128 1 (TECO's prompt sets this to 0)
256 0
512 0 (1 if VT support is present)
1024 0 (1 if VR12 support is present)
2048 0
The initial value of the ED flag is 1.
D.3 File Specification
The file access commands ER, EB, and EW accept a file
specification in the standard OS/8 format:
dev:filename.type
in which dev: is a physical device name or a user assigned
logical name; if dev: is not specified, the default DSK: is
assumed. The filename field must be specified in the commands
ER, EB, and EW and be a legal OS/8 filename. The type field is a
file extension and must be explicitly given if used (there is no
default). Any characters after the second will be ignored, thus
the filespecs FOO.TEC and FOO.TE are equivalent. The EB and EW
commands do not accept the extended notation for an output file
size
dev:filename.type[n]
specifying an output size allocation.
D.5 Backup Files
The EB command maintains one level of file backup on OS/8.
The pre-edited input file name is changed to
filename.BK
before the new output file is closed with the original name.
Only normal file closing commands (EC, EF, EG, and EX) cause this
renaming to happen. If TECO is aborted or the output file is
purged by the EK command, the input filename remains unchanged.
Note only one .BK file for a given name is kept; earlier .BK
backup files are deleted each time a new backup file is created.
A good policy to follow when editing is to close the edited
file frequently enough so that an unexpected incident would not
cause a substantial loss of work. Files should be backed up
regularly. TECO has the power to let an unsuspecting user alter
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a good file into a completely useless state. The SRCCOM program
can be used to verify an editing session.
D.6 Exit and Go
If TECO is exited via the EGstring$ command, the string is
passed to the system as the next command to execute. This string
may be any valid command or an indirect command file
specification. The command may be either a KBM or a CCL command.
This command is especially useful while running under BATCH.
If TECO is exited via the EG$ command, then OS/8 will
re-execute the last explicit compile-class command that was
executed that day. The commands that are considered to be
compile-class commands are:
COMPILE file
LOAD file
EXECUTE file
LINK file
MACRO file.
This feature, combined with OS/8's other remembering features,
minimizes the number of keystrokes necessary to do normal program
development. The programmer does not have to constantly type in
the name of the file he is working with. A typical debugging
session would look like this:
.MAKE FOO.MAC
*!type in assembly language file to be executed!
*EX$$
.EXECUTE FOO
(get error messages)
.TECO
*!fix bugs!
*EG$$ !re-compile and execute program!
(watch program work or repeat process)
D.7 <CTRL/C>
The action taken when the user types <CTRL/C> depends on
what TECO is doing. At command level <CTRL/C> is an immediate
action command. If typed as the very first character in a
command string (not necessarily the first keystroke) it aborts
TECO and returns to the keyboard monitor. If this was done
accidentally, TECO may be restarted (at your own risk) by using
ODT to branch to location 207 in your program's image. If
<CTRL/C> is typed int he middle of entering a command string,
then the ?XAB error message is given and TECO reprompts with its
asterisk. Note that if TECO executes <CTRL/C> as a command from
command level, TECO is aborted. If TECO executes a <CTRL/C>
command from within a macro, TECO is also aborted. If a <CTRL/C>
is typed while TECO is running, or while TECO is typing on the
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terminal, or while an error message is printing, then the ?XAB
error message is given and TECO reprompts with its asterisk.
Similarly, if <CTRL/C> is typed while TECO is waiting for input
because of a T command. Note that if TECO is performing I/O
using non-system handlers, the non-system handler may intercept
the <CTRL/C> and abort back to the keyboard monitor. In such a
case, you may attempt to re-enter TECO, however, part of your
file has been lost and good luck in attempting to issue an EF
command. Manually resetting the value of Z might recover your
data.
If TECO is executing commands or doing I/O, e <CTRL/C> will
stop the operation and generate the ?XAB error message.
Sometimes it is desireable for a TECO macro to detect when a
<CTRL/C> was typed. By detecting the <CTRL/C>, the macro can
exit cleanly back to command level (restore any flag values,
etc.). To do this, the macro sets Bit 0 (Octal 4000, Decimal
2048) of the ET flag. When a <CTRL/C> is typed, TECO will
automatically turn off Bit 0, but will continue execution of the
macro. The macro periodically checks Bit 0 and exits cleanly if
it ever goes off. If the <CTRL/C> trap bit is on, then the T can
read a <CTRL/C> typed at the terminal. It has an ASCII value of
3.
D.8 File Recovery
TECO can be a useful tool in recovering ASCII files lost on
a block replaceable device. TECO allows non-file-structured
devices to be opened in a non-file structured mode. This gives
the user the capability to open a disk and access ASCII data
anywhere on it, independent of file boundaries. To do this, you
must issue a command of the form
.SET dev: NOFILES
to the monitor to make it think that your disk is
non-file-structured. The command
ERdev:$
is used to open the device at which point _ (underscore or
backarrow) searches may be used to locate specific ASCII data and
transfer it to new output files. Note that files tend to get
reproduced, in whole or part, many places on a block replaceable
device; be sure to verify that any given text is indeed complete
and the correct version.
If the disk's directory has not been clobbered (or if you
are willing to create a new one), then it is not necessary to
turn the disk into a non-file-structured device. Merely open up
a file early on the disk for input and read through end-of-files
until you locate the lost file. To read through end-of-files,
you must use the /S switch on an ER, EB, or EW command. For
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example, the command
ERFOO.MAC/S$
will open the file FOO.MA for input and put tECO into "SUPERTECO"
mode. In this mode, TECO will not treat a <CTRL/Z> found in a
file as an end-of-file character. Instead, <CTRL/Z> will be
treated like any other character. It is not a line terminator or
a page terminator. This mode continues until an ER, EW, or EB
command is issued without a /S switch.
D.9 VR12 Graphics Support
If TECO is run on a PDP-12, TECO will automatically start up
in display mode, adjusting to both the size of the display screen
and to the presence or absence of the scroller.
On a PDP-12, TECO only permits one-page input and output
handlers.
See Section 5.15 for a description of the available commands
to interact with the display.
Various aspects of the display screen become immediately
obvious upon seeing them; the text pointer, its position and
shape and its position between lines; wrap around of more than
72 characters per line, and so on. Experiment with a scratch
file for more familiarity.
D.10 EXCEPTIONS
TECO-8 does not support the following commands which are
described in this manual:
1. Secondary streams (EP, EA, ER$, EW$)
2. Auxiliary command streams (EI)
3. Wildcards (EN)
4. Zeroing of directories (EZ)
5. Magtape commands (EM)
6. View command (V)
7. Bounded searches
8. Anchored searches
9. Search verification (ES)
10. Command verification (EV)
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11. Backward searches
12. Extended string build or match constructs (^Ex)
The following incompatibilities exist between TECO-8 and Standard
TECO:
1. In octal mode, the digits 8 and 9 are not treated as
errors when occurring in a numeric string.
2. The *q immediate action command is not implemented.
Instead, the immediate action command * has the same
effect as *Z of the standard. (The immediate mode
command ^S is still accepted for compatibility with OS/8
TECO V5.)
D.11 Chaining to TECO
A user program may chain to TECO passing it a command to be
executed. There are two formats that such a command may take.
Format 1 (the TECO command format) passes TECO a valid TECO
command to be executed. This TECO command is placed in a buffer
starting at location 17600, one 7-bit ASCII character per word.
A negative word represents a pointer to a continuation buffer in
field 1. There may be any number of continuation buffers, but
they must all begin above location 4000 in field 1. Since TECO
clobbers most of field 1, these buffers must in fact start above
location 7400. TECO will never load into page 7400 of field 1.
The buffer ends with a fullword 0.
Format 2 (the CCL command format) passes TECO a CCL command
to be parsed and executed. Such a command usually begins with
the words TECO, MAKE, or MUNG, but is not limited to these words.
Such a CCL command is placed in a buffer starting at location
17601, one 7-bit ASCII character per word. Location 17600 must
be a fullword 0 to specify that this format is being used. A
negative word in the buffer represents a pointer to a
continuation buffer in field 1 as described above. The buffer
ends with a fullword 0. If this format is used, the passed CCL
command will be parsed and executed by TECO.TEC as described
below. A user may write his own TECO.TEC, thus implementing his
own CCL commands. There is no limit to the possiblities, other
than the user's imagination.
D.12 User Initialization
If a user has a file called TECO.INI on SYS:, then when TECO
starts up (via a CCL command, it will execute the contents of
this file (as a TECO macro). This file must contain a valid TECO
program (which will execute out of Q-register W). God help you
if you have any errors in this program. This start-up file must
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not modify itself (Q-register W) and must not modify the contents
of Q-register V. It should not indiscriminately modify the
contents of Q-register Z or the text buffer. TECO.INI will be
executed before TECO opens any files. That is, if TECO was
invoked via a MAKE command, TECO.INI will be executed before the
EW command (for the MAKE) is executed. At this point, the text
buffer will contain a copy of the CCL command that invoked TECO
(assuming your monitor has TECO.TEC support). However, TECO has
not as yet parsed this line. The user may examine this line for
himself, and modify it, but you had better know what you are
doing (and do it right!). TECO.TEC will parse the contents of
the text buffer at the conclusion of execution of TECO.TEC.
If your monitor does not have TECO.TEC support, or if a user
program chained to TECO passing it a TECO command (rather than a
CCL command), then the initial TECO command will be in Q-register
Z when TECO.INI gets control. That command has not as yet been
executed. The initialization file may examine the contents of
Q-register Z to determine what TECO command will be executed and
proceed accordingly. It may also modify the contents of
Q-register Z (but you better know what you are doing).
In this case, TECO.INI is started up via the sequence
@:ER/SYS:TECO.INI/"SYHXWHK@^UZ^@teco
command^@MW+0ES.,.XWMZES"N0ESMX'$$
which loads TECO.INI into Q-register W, loads the chain argument
consisting of an appropriate teco command into Q-register Z, and
temporarily stores the value returned by TECO.INI in the search
verification flag (this feature may change in a subsequent
release). Q-register W and ES are cleared before the
post-processing command in Q-register X is executed. Note that
the chain argument may not contain any embedded nulls.
D.13 RETURNED VALUES FROM TECO.INI
TECO.INI may also return a value. If your monitor does not
support TECO.TEC, then only two values are permitted. Returning
a 0 (or not returning anything) is the normal sequence of events.
Returning a 1 means that TECO should execute the contents of
Q-register X (via an MX command) after it executes the initial
TECO command (in Q-register Z). TECO.INI may set up Q-register X
with the appropriate post-processing commands. A typical use of
this feature would be to have TECO.INI load up Q-register I with
an editing macro and then put an "MI" command in Q-register X for
subsequent execution. If your monitor does have TECO.TEC
support, then TECO.TEC can support additional returned values.
It is recommended that TECO.TEC support the returned values of 0
and 1 as above, but in addition, it may support additional values
determined by the user.
Note that TECO.INI is not invoked if TECO is started with a RUN
or R command.
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D.14 TECO.TEC Support
If the version of CCL you are using to invoke TECO supports
TECO.TEC, then it will chain to TECO with a 0 at location 17600
and will pass TECO the invokig CCL command (beginning at location
17601). If TECO is invoked in this manner, it will parse this
CCL command by executing the TECO command line parser macro
stored in SYS:TECO.TEC. This macro can be modified by the user
to parse switches or do any special processing that is desired.
TECO.TEC is started up via the command
@I^@ccl command^@:ER/SYS:TECO.TEC/"F^ACan't find SYS:TECO.TEC
^A^C^CA.,ZXV.,ZKMV.,.XV$$
which puts your CCL command in the text buffer and then loads
(the first page of) TECO.TEC into Q-register V. TECO.TEC is then
executed with the MV command and then Q-register V is cleared.
It is the responsibility of TECO.TEC to parse the command line in
the text buffer and do the appropriate processing and clean-up.
It is also the responsibility of TECO.TEC to execute a user's
start-up file (TECO.INI) if one is present. Note that TECO.TEC
is not invoked if TECO is started via a RUN or R command. Also
note, that the CCL command may not contain any embedded nulls.
D.15 Overlays
The key to writing fast TECO programs lies in understanding
TECO-8's overlay structure. If TECO-8 is run in 16K or more (20K
or more if VT support is present), then the overlays will be
memory-resident rather than disk-resident. Although this is much
faster than swapping from the disk, swapping from memory still
involves some overhead, so it would be wise to structure your
TECO program to minimize the number of swaps necessary.
The overlay structure is designed so that the minimal number
of swaps will be required unless obscure TECO features are used.
There are five overlays to TECO:
1. The I/O-overlay. This overlay handles file opening and
is initially resident. Thus no swapping is necessary to
do in initial ER, EW, or EB.
2. The Q-overlay. This overlay contains most of the
frequently used conditional commands and branching
commands. It is intended that this overlay swap in once
and remain in memory until TECO is exited.
3. The X-overlay. This is the exit overlay and handles
commands needed only when TECO is exiting, such as EX,
EF, EC, and EG. It is intended that this overlay will
swap in only once when you are ready to leave TECO.
4. The F-overlay. This overlay contains the flag commands
and other little-used commands. It is intended that
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this overlay be not used at all, or if it is used, it
will be used so infrequently that it will not slow down
system performance.
5. The E-overlay. This is the error overlay. It is
swapped in only when an error occurs. It is intended
that this overlay never be swapped in.
To write efficient TECO code, the user must know exactly
which commands are handled by which overlay. This information is
summarized below.
Overlay Commands
I-overlay ERfile$, EWfile$, EBfile$, :ERfile$, :EBfile$
Q-overlay Otag$, n"Xthen|else', n;, search;, n<...>, <...>
X-overlay EC, EG$, EGcmd$, EF, EK, EX,
*q, ?, nEJ, n^_, V, ^B, ^E, ^F, ^L, ^N, ^Uqtext$
F-overlay ED, EH, EO, ES, ET, EU, ^D, ^O, ,break \, n\, n=,
n==, n:=, n:==, |
Several things are immediately obvious. The command 0TT should
always be preferred tot he V command. ELSE clauses should be
avoided. (In future releases, we will try to move the processing
of the | command into overlay Q.) The commands \ and = should be
used as infrequently as possible from within long-running macros.
Xq is preferred to ^Uq to load up a Q-register. -n-1 is
preferred to n^_ to take a one's complement. Radix changes
should be avoided. Flags, such as ET and ED, should be set once
at the beginning of a macro, and then not fiddled with if at all
possible.
D.16 Installation Instructions
The source of TECO consists of the following modules:
TECO.MAC Main module
TECINI.MAC Initialization module
TECTBL.MAC Tables
TECDEF.MAC Global definitions
TECO12.MAC VR12 support
TECOVT.MAC VT support
TECOVI.MAC I/O-overlay
TECOVQ.MAC Q-overlay
TECOVX.MAC X-overlay
TECOVF.MAC F-overlay
TECERR.MAC E-overlay and error processor
TECSRH.MAC Search processor
TECNUM.MAC Arithmetic processor
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Each of these modules should be assembled (using MACREL V2 or
later). This can be accomplished via the command
.MAC TEC???.MAC
if your monitor supports wildcards in compile-class commands.
The resulting relocatable modules are then linked together
(using LINK V2 or later) to produce the executable TECO.SV image
which should be put on SYS: (but it may reside on any device).
If your monitor supports TECO.TEC, then TECO.TEC must be placed
on SYS:. D.17 ARITHMETIC PRECISION
TECO-8 performs 13-bit arithmetic except that multiplication
and division by negative numbers gives unpredictable results.
All numbers stored in Q-registers are 13 bits long. Number
stored in flags (such as ET, EU, etc.) are only 12-bits long.
When storing a number into a flag, the high order (sign bit) is
lost. When using the value of a flag in an arithmetic
expression, the 12-bit value is sign extended first.
D.18 ALTERNATE STARTING ADDRESS
The normal starting address of TECO is location 00200. In
this (normal) mode, TECO will simulate tabs by spaces on type-out
and will simulate vertical tabs and form feeds by line feeds. If
your terminal has hardware tabs and vertical tabs (such as a
KSR-35), then TECO can take advantage of these features. To
enable this ability, you should change TECO's starting address to
be 05200. This can be done by the monitor commands:
.GET SYS:TECO
.SAVE SYS:TECO;5200
D.19 VT05 SUPPORT
TECO will automatically handle command string scope editing
correctly on a VT05. The VT support (obtained via use of the -1W
command) will handle VT05's correctly. The VTEDIT macro does not
currently support the VT05 keypad.