Merlin  Executive Mode

4.  Executive Mode

The  EXECUTIVE  mode  is  the  program  level  provided  for   file
maintenance operations such as loading or saving code or cataloging
the disk.  The following sections summarize each command  available
in  this  mode.  Note that each command consists of a single letter
WITHOUT a RETURN <R> key operation. If the command requires further
data, you will be prompted for same.

4.1  C:Catalog

After displaying the catalog, this command accepts any disk command
you  may  wish to give, using standard DOS syntax. Unlike the LOAD,
APPEND and SAVE, you must type the ".S" suffix when referring to  a
source  file.  This  facility is provided primarily for locking and
unlocking files. Do not use it to load or save files.   If  you  do
not wish to give a disk command, just Type:<R>.  In order to cancel
a partially typed command you can:

  a.  Type:^X

  b.  Assure that the  command  has  the  wrong  syntax  by  typing
      multiple commas.

  c.  Backspace to the beginning of the line, Type:^H  or  use  the
      back arrow.

If you Type:^C<R> after the "COMMAND:" prompt,you will be presented
with  the  EXEC prompt of "%". You can then issue any EXEC command,
such as "L" for LOAD. This permits you  to  give  an  EXEC  command
while  the  catalog  is still on the screen. Typing of ^C<R> at the
catalog pause point causes printing of the remainder of the catalog
to be aborted.

4.2  L:LOAD

Load is used to load a source file from disk. You will be asked for
the  name  of  the file. You must not append ".S" since Merlin does
this automatically.  From the foregoing you will  notice  that  ALL
source  files must end in ".S" or Merlin will not load them. If you
have such a file, refer to the Merlin Catalog command and  use  the
DOS RENAME facility to remedy the situation.

If you Type:L by mistake, just Type:<R><R> and the command will  be
cancelled without affecting any file that may be in memory.

After a Load or Append command, you are automatically placed in  th
EDITOR  mode,  just  as if you had typed "E".  Subsequent Load/Save
commands will  display  the  last  used  filename,  followed  by  a
flashing  "?". If you Type:Y, the current filename will be used for
the command. If you type any other character (e.g. <R>), the cursor
will  be  placed on the first character of the remembered filename,
and you may type in the desired name. Of course, tracing  over  the
remembered  filename with the arrow keys (<- and ->) will cause the
characters traced over  to  be  entered  as  all  or  part  of  the
command's  filename.   This  is  a  useful feature when you wish to
read/save a modified file with the same  name  except  a  different
suffix.  All you do in this case is Type:L<R>(trace with arrow keys
to  desired  point)"type  remainder"<R>  and  the  file   will   be
read/saved  under the new name. Practice with "uncritical" files if
you feel unsure about this feature.

If you type <R> instead of entering a filename, the command will be
cancelled.

4.3  S:Save

Use this command to save a source file to disk. As  with  the  Load
command,  you  must NOT specify the ".S" suffix, Merlin will supply
it.  If you do Type:filename.S, it will be saved as "filename.S.S".
On  subsequent  Load/Save/Append  commands,  you  would  Type:L/S/A
"filename.S".  Merlin would the  append  from  "filename.S.S".   As
with Load, you can type the appropriate number of <R> to cancel the
command PRIOR to any other keyboard input.

Note that the address and length of the file are shown on the  menu
and are for informational purposes only and should (cannot) be used
for Saving the file.

If the file in memory was entered totally  from  the  keyboard  and
this  is  the  first time it is to be saved, there is no remembered
filename (obvious, don't you think?).  However,  if  the  file  was
read  using  the  Load  command or it has been saved before in this
session, there will be a remembered filename (equally obvious  from
the  previous  comment).  The same procedures with regards to using
the arrow keys or not, apply here.

4.4  A:APPEND

This reads in the specified file and Appends (concatenates)  it  to
the end of the file already in memory.  The Append command does not
affect the remembered (default) file in any way. In fact, if Append
is  used  when there is NO file in memory it will load the file and
still will not change  the  remembered  filename  (NULL);  that  is
dedication to design!

4.5  D:Drive

Typing the command "D" causes the default drive to toggle between 1
and  2.   The  currently selected drive is shown on the menu.  When
Merlin is first BRUN, the selected drive will be the  one  selected
by  the  BRUN.  Of course, booting Merlin with PR#6, open apple,...
causes the default drive to be 1.  There is no command  to  specify
the  slot  number.  However, this can be accomplished by typing "C"
for CATALOG which will display the current disk's directory. At the
end  Type:CATALOG,Sn,Dm",  where  n is the new slot number and m is
the drive in that slot.

The above will Catalog the selected  drive  and  more  importantly,
change the slot number Merlin uses for it's disk commands.


4.6  E:EDITOR

This command places you in the EDITOR/ASSEMBLER mode.

NOTE:  The defaults for a number of EDITOR commands  are  set  when
moving  from  the  EXEC  to the EDITOR mode.  If you change some of
these defaults while in  the  EDITOR,  then  "Q"uit  to  the  EXEC,
followed  by  "E"  to go back to the EDITOR; These defaults will be
changed back to their default value. Those commands that experience
this  phenomenon, are commented as such in the EDITOR section. Stay
alert!

4.7  O:Object Code Save

You are permitted to use  this  command  ONLY  after  a  successful
assembly  (ASM)  of  a  source  file. In this case you will see the
address and length of the object code on  the  menu.  As  with  the
source address, it is given for information only.

The object address shown is that of the program's ORG (or $8000  if
an  ORG  is  not  supplied)  and  not  the  actual  location of the
assembled code (which is $8000 or whatever OBJ you have used).  No,
the  previous  sentence  did not take leave of it's mind.  You have
got to  get  it  straight  that  when  we  say  "object",  we  mean
 "object", not "object".

Enough of this mirth. The object address shown  on  the  EXEC  menu
refers  to  the  address that the object program will be loaded too
when it is BRUN/BLOADed.   Unfortunately,  there  is  an  assembler
pseudo-op  called "OBJ" that is used to specify where the object is
to be stored during the assembly process.  With this in  mind,  the
first sentence is saying, "If OBJ is not specified, the object code
is stored at $8000 during assembly (almost always exactly what  you
want).   Furthermore,  If  an  ORG  statement  is not provided, the
program will be defaulted to run at location $8000." Now,  back  to
the big "O" command.

When using this command you are asked for the name  of  the  object
file  (the  source  filename  without the ".S" is the default). The
object will be saved under whatever  name  you  chose  WITHOUT  any
suffix being supplied by Merlin.

4.8  Q:Quit

Q exits to BASIC. Later, you may  re-enter  Merlin  by  typing  the
"ASSEM" command.  The re-entry will be a warm start, which means it
will not destroy the source file currently in memory.  While Merlin
will not destroy the source in this case, what did you do while you
were out there where we couldn't watch you? Did  you  do  something
that did destroy Merlin's memory?

The moral of this is: Why take chances? store your source prior  to
exiting Merlin and then reload it when you return. If the source is
small and can be checked and/or retyped in a short time, go ahead.

The idea behind "ASSEM" is to allow  you  to  exit  and  type  disk
commands  if it is more convenient than the method provided via the
"C" command.

4.9  R:Read

This command reads text files into Merlin. They are always appended
to  the  present  contents  of  the buffer.  If this is not what is
desired:

  1.  Enter the EDITOR and Type:NEW<R>
      This will cause the buffer to become empty.

  2.  Exit back to the EXEC mode. Type:Q<R>

  3.  Now perform the "R"ead command and the file will be  appended
      to NULL.

Note that the "R"command always causes the default filename  to  be
the last file read in this fashion.

When the read is complete, you are placed in  the  EDITOR.  If  the
file  contains  lines  greater  than  255  characters, they will be
divided into two or more lines by the Read routine.

The file will be read only until it reaches HIMEM, that will  cause
a  memory  error if it attempts to go beyond and only the data read
to that point will remain  (we  had  hoped  to  preserve  the  data
not read to that point. However, you know how it goes on government
jobs).

The Read and Write commands will prefix  a  "T."  to  the  filename
unless you precede the filename with a space or any other character
in the ASCII range of $20  through  $40.  Since  the  character  is
simply  a  flag  to Merlin to tell it to not prefix the "T." to the
filename, you are showing off if you use anything except  a  space.
I  repeat,  the "no T." character will not be given to DOS and will
not become part of the actual filename.

4.10  W:Write

This writes a Merlin file into a disk text file instead of a binary
file.   See  the previous Read command for a discussion of the "T."
prefix.

The speed of the read (poet) and Write  routines  is  approximately
that of a BLOAD or BSAVE.  However, the Write routine does a VERIFY
after the Write. This will  convince  you  (rightly  so)  that  the
process is taking much longer than a "normal" "S"ave.