Oakland CPM Archive/oakcpm.iso/cpm/cpminfo/cpmnotes.pqn/CPMNOTES.PRN

Text File | 1985-02-10 | 12.5 KB | 385 lines

                A BRIEF OUTLINE OF CP/M AND CP/M COMMANDS

                              Eli Freedman
                               ABC Br, IBD

    These  notes are necessarily sketchy.   Not every CP/M utility is
    mentioned; of those that are, not every ramification is covered.

    CP/M  stands  for Control Program for Microcomputers.   It  is  a
    collection of computer programs for the Intel 8080 and the  Zilog
    Z80  chips.   CP/M  handles  all of the sometimes  intricate  and
    always tedious details of input/output (I/O),  including communi-
    cation among processor,  disks,  console,  and printer, including
    disk-file maintenance.

    For the North Star Advantage,  CP/M is furnished on a 5-1/4  inch
    floppy  disk where the system occupies the first 3 tracks;  these
    are called the system tracks.   When you press the red button  on
    the back of an Advantage and then the RETURN key, the CP/M system
    is loaded into the computer.   This operation is called "booting"
    the computer;  note that it is not done with the foot!   When the
    computer  is booted,  CP/M loads itself into the computer's  core
    memory.   It  occupies approximately 6000 (decimal) bytes at  (or
    near)  the  top of the memory,  and also the first 256  (decimal)
    bytes starting at 0.

    There are two kinds of "booting":

          Alternate       How
    Name    Name       Accomplished                  Why
    ----- --------    -------------        --------------------------
    cold    hard     turn machine on        start-up
                     press red button       resume after crash
                     special program

    warm    soft     press ^C               read disk directory

    After  booting,  the  screen displays A>,  meaning that  you  are
    "logged  in" on drive A.   If you type B:,  the screen shows  B>,
    meaning that the logged drive is now B.   WordStar and many other
    programs require that you know which drive is the logged one.

    The  principal  components  of CP/M are  the  Basic  Input/Output
    System (BIOS),  the Basic Disk Operating System (BDOS),  and  the
    Console Command Processor (CCP).   These programs are all located
    in  the  "high memory" part of CP/M.   The largest amount of  the
    computer's  random-access  memory lies between the two  parts  of
    CP/M and is referred to as the Transient Program Area (TPA).  All
    of the TPA is available to the user;  some CP/M programs also use
    it.






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    CP/M  has two kinds of commands,  built-in  and  transient.   The
    built-in commands (ERA, TYPE, SAVE, REN, and DIR) are in the CCP,
    and do not change anything in the TPA.  Also, they do not show up
    in the directory listing of the disk.   The transient commands do
    show  up in the directory (unless you go to the extra trouble  of
    hiding them--it can be done) and they are loaded into the TPA for
    execution.

    FILE NAMES.  Almost all CP/M commands work on file names.  A file
    name  is 1 to 8 letters or numbers,  plus an optional  extension,
    which  is a period and 1 to 3 letters or numbers.   Some  special
    characters  can  be  used in file names.   The drive  letter  may
    appear in front of the name,  followed by a colon.   If the drive
    letter  is not used explicitly,  the logged drive is  assumed  by
    default.

    Examples: MYFILE.EXT    URFILE     B:afile.for      A:CPNOTES.TXT

    Note   that  A:MYFILE  is  different  from  B:MYFILE;   likewise,
    MYFILE.TXT is not the same as MYFILE.BAK.

    Certain extensions have special meanings:

                 .FOR  A FORTRAN source file.
                 .BAS  A BASIC language file.
                 .REL  Relocatable code produced by various
    compilers.
                 .ASM  Assembly language source file.
                 .HEX  The output from certain assemblers.
                 .PRN  A print listing produced by some compilers.
                 .COM  A command file (executable program).
                 .SUB  A SUBMIT file (similar to a CCL procedure).
                 .BAK  A backup file; produced by WordStar and some
    other programs.
                 .MAC  A file for the Microsoft M80 macro assembler.

    These uses are required in most cases.   For example:  the Micro-
    soft  FORTRAN compiler will not compile a program without a  .FOR
    extension; you cannot execute a program that does not have a .COM
    extension.  I recommend that you use extensions only to designate
    the  kind of file;  don't rely on the extension alone (except for

    WILD-CARD  DESIGNATORS.   In many cases one wants to refer  to  a
    class of files,  not just one.   This is done with the "wild-card
    designators,"  * and ?.   The ?  matches any letter;  the * means
    "any."










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    Examples:

              *.FOR means any file with the extension FOR.

              AB??????.* means any file whose name starts with AB and
    has any extension.

              AB??????.TXT  means any file whose name starts with  AB
    and has extension TXT.

    SOME  SPECIAL  CONTROL CODES.   Control codes  are  generated  by
    holding  down  the key marked CNTRL (or CONTROL)  while  pressing
    another.   In  text,  the up arrow,  ^,  is used to designate the
    CNTRL key.  In CP/M, certain control codes have special meanings:

                 ^C   Interrupt a command or program (may not  always
    work);  perform  a "soft boot" (read the directory on  each  disk
    drive).

                 ^S  Stop/start the screen display.

                 ^P  Start/stop the printer; when "on", any text that
    appears on the screen will also be printed.

                 ^X  Erase command line, return to col. 1

    BUILT-IN COMMANDS.

              DIR [A:URFILE.EXT]
    Display the directory for a file or a disk.

    Examples: DIR
    Shows the directory for the logged disk.

              DIR B:
    Shows the directory for disk B no matter which disk is the logged
    one.

              DIR A:*.COM
    Shows  the  directory for all files on the disk on drive  A  that
    have the extension COM.

              DIR B:MYFILE.*
    Shows  the directory for all files on drive B that have the  name
    MYFILE, no matter what their extension is.

              REN NEWFILE.EX2=OLDFILE.EXT1
    Rename a file. The old file name is replaced by the new file name
    in the directory; the contents of the file are not disturbed.

              ERA FILENAME
    Erase  the name of the file from the directory.   The contents of
    the  file  are not disturbed,  and can be  retrieved  by  special
    programs.


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    Examples: ERA B:*.BAK
    Erases on all files on drive B with the extension BAK.

              ERA A:MYFILE.TXT
    Erases only MYFILE.TXT on drive A.

              ERA *.*
    Careful!  This command will erase on files on the logged disk.

    SOME CP/M TRANSIENT PROGRAMS

    All  programs that run under CP/M have the extension  .COM.   The
    program  is  executed by typing the name without  the  extension.
    Generally  either lower- or upper-case letters may be  used,  but
    there are exceptions (e.g., in FORMAT).

              STAT

    Display  size and attributes of a file or files or a disk;  also,
    change  the  designations of I/O units.   STAT by  itself  merely
    tells  you how much space is left on the logged drive.   STAT  B:
    tells you how much space is left on the disk on drive B:.

    STAT  A:*.* tells you the name of every file on the disk  now  on
    drive  A:,  and its attributes.  There are two  attributes:  R/W,
    meaning both reading and writing are permitted;  and R/O, meaning
    the file is read-only.

    STAT  B:*.COM gives this information for every .COM file on drive
    B:.   STAT also permits you to change device assignments; see the
    references.

                 COPY
    Copy  the contents of one disk onto another  entirely,  including
    the system tracks.   COPY is self-guiding;  just type the command
    and follow the instructions.  Note that COPY refers to the drives
    by number, not by letter.

                 FORMAT
    A new disk cannot be used until it has been formatted.   For CP/M
    systems,  this  means that all of the tracks are filled with  the
    format character (E5 HEX).  This is accomplished by typing FORMAT
    and then following the directions that appear.   A disk does  not
    have  to  be formatted if the very next thing you do to it is  to
    COPY something onto it,  since this automatically initializes the
    disk.

                 PIP
    Copy one or more files to other files;  the new files do not have
    to be on the same drive, but they may be.






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    Examples:  PIP B:NEWFILE.EX2 = A:OLDFILE.EX1
               PIP NEWFILE = B:OLDFILE
               PIP  A:*.* = B:*.*  Copies every file from B:  to  A:;
    the  names  remain  the same,  except for  the  change  in  drive
    designation.

               PIP  B:=A:*.FOR  Copies every FORTRAN file on drive A:
    onto drive B:

    PIP  can be invoked alone;  it then responds *.   You  then  name
    files two by two (i.e., new and old) for copying.  Terminate with
    a CR.

               SUBMIT FILE.SUB PAR1 PAR2 PAR3 ...

    A  great  program that permits you to operate in almost  a  batch
    mode.  The quantities PARi replace dummy arguments.  You build up
    a  sequence  of CP/M commands in a file whose extension  must  be
    you place the dummy arguments,  $1,  $2,  etc.   When the file is
    then  submmitted,  CP/M  will make the substitutions,  print  the
    command, and then execute it.

    Example: Suppose you create a file TEST.SUB whose contents are

               PIP $1:$2.TXT=B:$3.TXT
    Then you type
               SUBMIT TEST A GOOD BAD

    The screen will show the complete command

               PIP A:GOOD.TXT=B:BAD.TXT

    and then the program will execute.

               SAVE n FILENAME
    This  command transfers n*256 bytes from memory starting  at  256
    (decimal)  to the named file on disk.   It is used after  working
    with  DDT (see references).   Also,  some communication  packages
    (e.g.,  CMOD)  transfer  data from an external computer  to  your
    computer's memory; SAVE is then used to store the data on a disk.

               SYSGEN

    It is very convenient to be able to boot your computer from every
    disk you use.  This means that every disk must have a CP/M system
    on it.   (I also recommend that every disk have PIP,  FORMAT, and
    COPY on it.)

    There are two ways in which you can put a CP/M saystem on a disk.
    You  can  use  COPY,  which copies everything from  one  disk  to
    another,  track for track.  This method has the disadvantage that
    you then have to remove all of the files that were also copied.




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                             SOME REFERENCES

    In my opinion, the best reference on CP/M is:

    Rodnay Zaks, "The CP/M Handbook," Sybex; 1980.

    J.  N.  Fernandez & R.  Ashley, "Using CP/M," John Wiley; 1980 is
    written   in   a  "programmed  learning"  style  that   I   found
    infuriating.  It  is  a  good  self-teaching  text,  but  a  poor
    reference book.

    CP/M  is  a product of Digital Research.   This company  supplies
    Manuals  with  the system when you buy it.   They  have  a  well-
    deserved reputation for denseness and incomprehensibility.

    An interesting book is

    Jack D.  Dennon, "CP/M Revealed," Hayden; 1982.  It gives some of
    the details of how CP/M does its stuff.

                             ACKNOWLEDGMENT

    Many  thanks  to George E.  Keller for invaluable assistance  and
    advice.





























                                                  version  2.01/9-I-84


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