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Overview of CHDIR Installation Basic Definitions Moving Into a Directory Creation of New Directories "On the Fly" Displaying the Directories Setup Mode Planning a Directory Structure :Overview of CHDIR CHDIR (CHange DIRectory) is a program which gives a CP/M or CP/ZM system a new virtual directory structure. Ever since CP/M 2.0 came out, users have been forced to refer to the environments that their files are located in by user number and disk name. This was an improvement over CP/M 1.4 in that projects and files associated to each other for one reason or another could be logically grouped together into a user area on a particular disk and could easily be kept separate from other files. This improvement is desirable and useful, but there are some capabilities lacking in this design that limit its usefulness. One such capability is the need for duplication of a COM file or directory entry for a COM file in order to access this file from more than one user area. Another such capability is the human- interface requirement for a logically-named user area that indicates the purpose of the user area as opposed to simply providing a number for it. Under CP/M 2.x, unfortunately, if you wanted to issue a command, you had to have a copy of that particular COM file in your current user area in order for the operating system to find the command and load it. User areas were of less use because of this, since several commonly-used commands had to be duplicated into each user area. This took up more disk space and was somewhat awkward. In answer to this and other desired capabilities, ZCPR was created. Placed on top of the CP/M CCP, ZCPR provides a new command processor for the CP/M user which is upward compatible with the old command processor but adds several new features, including a command-search hierarchy. Now, when a user issues a command, ZCPR will search for it if it is not found in the current user area on the current or specified disk. The user can specify the path to follow; however, ZCPR is initially configured to search the current user area on the current disk, user area 0 on the current disk, and user area 0 of disk A before producing an error message. With ZCPR it is no longer necessary to keep several copies of files on disk in order to use the user areas. The user areas and disks were still addressed as separate elements of an overall file system, however. The user had to be constantly aware of where he was, and ZCPR also gave him a different prompt which indicated the current disk and user number. If a user wished to employ user area 1 for C program development and user area 2 for C source code storage, he had to note for himself that this is where these things were. Now, CHDIR is introduced which adds a new outlook to the user environment. The user may now give each user area/disk a logical name (such as C-DEV or C-PGMS) and not worry about where they actually are on disk. Combined wisely with ZCPR or ZMCPR, all utilities may be placed in a commonly-scanned directory (user area/disk) so they will always be found by the CPR, and the user's entire microcomputer disk system now resembles one large disk with several named subdirectories which contain related files. CHDIR artificially imposes a named directory structure onto CP/M and CP/ZM. Each named directory corresponds to a user area on a particular disk, and the user need never be concerned with what user area he is in if he uses ZCPR or ZMCPR with CHDIR. Each disk/user area is called a directory and may be given a logical name (up to 8 characters long). The simplest form of the CHDIR command is: CHDIR <directory name> where <directory name> is a logical name (8 chars max) recognized by CHDIR. This command logs the user into the user area/disk associated with the indicated directory name. For example, given the following environment: User Disk Directory 10 A SYS1 11 A SYS2 8 B C-DEV 7 A C-PGMS 7 B PAS-DEV 6 A PAS-PGMS the command: CHDIR C-DEV logs the user into user area 8 on Drive B:; also, the command: CHDIR PAS-PGMS logs the user into user area 6 on Drive A:. CHDIR combined with ZCPR or ZMCPR, then, provides a useful named-directory working environment which is completely compat- ible with CP/M, and almost all CP/M programs can run without modification in this new environment. CHDIR employed in a hard disk environment is especially useful in that the different logical disks associated with the hard disk may now be grouped into one named directory structure and need no longer be treated as separate disks. In addition to the named directory structure, CHDIR also creates a priveleged user environment. This environment, which only becomes effective if the USER command (and other such facilities) are removed from ZCPR (and the COM files removed from the disk), defines two classes of users. A normal user only has access to certain user areas (0 to 9 by default), and a priveleged user has access to all user areas. In order to move into user areas greater than 9, a password must be known. Once in a priveleged user area, no password is necessary to move to any other user area. This feature gives a certain amount of protection to systems, such as Remote Bulletin Board Systems, against hostile users. Certain priveleged commands, such as debuggers and language utilities, may be placed into the protected user areas and employed only by those who know the password. Two different command processors can even be made to come into play (in the case of ZMCPR), where the normal user sees a menu-driven set of commands while a priveleged user sees a ZCPR-like command line. Refer to the documentation on ZCPR and ZMCPR for further details. :Installation Installation of CHDIR is performed in two parts: Compiling CHDIR and Initializing the Internal Buffers of CHDIR. Before compiling CHDIR, there are several internal default values that the user may wish to set in the source code of the program. These values and their meanings are: defname -- default name for the COM file of CHDIR; change this if you want CHDIR to be known by some other name after initialization; this name may also be later changed under Setup Mode dirmax -- maximum number of directory names allowed; a minimum value of 64 is recommended syspass -- default System Password for CHDIR; this is up to 20 characters long, and case is significant; this may be later changed under the Setup Mode sysuser -- lowest user number for a priveleged user; default value is 10; values should be in the range from 0 to 15 tryent -- number of tries permitted to enter a priveleged directory before CHDIR aborts; default value is 1 tryset -- number of tries permitted to enter Setup Mode before CHDIR aborts; default value is 3 exitcmd -- command to be executed if a valid password is not given in the required number of tries; default is no command; this should be the name of a COM file, like "HOSTILE" for HOSTILE.COM, and should be in upper-case All of these defined values are located just after the initial comments within the program source code. Part I -- Compiling CHDIR CHDIR was compiled by the BDS C compiler. No special flags or options are necessary. Once compiled, however, the COM file produced must be modified so that the stack used by this program does not overwrite the CCP or CPR. To do this, the user may use the NOBOOT program from the BDS C user's group or manually modify the code at the beginning of the COM file. Using the 1.45 version of BDS C, the first few bytes of the COM file load the HL register pair from locations 6 and 7 and then load the SP register from HL. This is followed by several NOPs. To correct the stack problem, replace this sequence with an LXI D,-A00H, DAD D, and SPHL starting with the SPHL instruction. Example follows: Original Code New Code LHLD 6 LHLD 6 SPHL LXI D,-A00H NOP NOP NOP DAD D NOP SPHL Once this has been installed using a debugger like DDT, the COM file may be resaved to disk using the SAVE command, and the user is ready to proceed to Part II of the installation. If the NOBOOT command is available and works for the user's version of BDS C, then this manual procedure may be replaced by the command: NOBOOT CHDIR.COM Part II -- Initializing CHDIR Buffers Once CHDIR.COM has been patched so that it's stack does not overwrite the CCP or CPR, then its internal buffers must be initialized. This is done to perform two basic functions: 1) define the password for the priveleged user 2) clear the directory name table To perform this initialization, issue the command: CHDIR /S This places the user into SETUP Mode. If the user runs this command from user areas 0 to 9, he will be asked for the "System Password", which is initially "chdir" (no quotes). If the user runs this command from user areas greater than 9, he is declared priveleged and is not asked for the password. Once into SETUP Mode, the user is prompted with: Setup Command (? for Help)? He should issue the following commands to perform the initialization: I or i -- clear the directory name table; the user will be prompted with "Verify Initialization (Y/N)?", to which he should respond with a Y or y. P or p -- set the password; the user will be prompted with "New System Password?" and 20 dots to indicate the size of the allotted password; he may then type the new password, and case is significant ("test" is NOT the same as "TEST") X or x -- Exit and rewrite CHDIR.COM to disk; the user will be prompted with "Write New File (Y/N)?", to which he should respond with Y or y, and then "Name of File (RETURN=CHDIR.COM)?", to which he should strike the RETURN key. SETUP Mode is described in more detail later in this HLP file. The procedure just outlined is all that is required for initialization, and CHDIR is now ready for use. The first step is to plan and define the named directories. The other sections of this HLP file tell you how to do this. :Basic Definitions The following symbolic names are defined: <directory name> <du> <password> A <directory name> may contain up to 8 characters. The characters "*", "?", ".", and "/" should not be used as part of the directory name since the CCP, CPR, or CHDIR routines perform special processing on them. Lower-case letters are automatically converted to upper-case. <du> is the disk letter and user number combination which is assigned to the <directory name> given. It is a single letter (lower-case is converted to upper-case) in the range from A to P followed immediately by the digits of the user number (0 to 15). <password> is the System Password for CHDIR. This is a string of up to 20 characters. Case is significant ("test" is NOT the same as "TEST"), and any printable character may be used as part of the password as a general rule. :Moving Into a Directory The CHDIR command of the following form is used to move into a directory: CHDIR <directory name> A <directory name> may contain up to 8 characters. The characters "*", "?", ".", and "/" should not be used as part of the directory name since the CCP, CPR, or CHDIR routines perform special processing on them. Lower-case letters are automatically converted to upper-case. If the user is not priveleged (residing in user area 10 or greater, by default) and the name of a priveleged directory is given, he will be asked for the System Password. In this case, he will be given only one try before the command aborts. Examples: CHDIR C-DEV CHDIR work chdir cpci81 chdir 1temp :Creation of New Directories "On the Fly" The CHDIR command of the following form is used to create new directories at will: CHDIR <directory name> <du> <directory name> is of the same form as described above. <du> is the disk letter and user number combination which is assigned to the <directory name> given. It is a single letter (lower-case is converted to upper-case) in the range from A to P followed immediately by the digits of the user number (0 to 15). If the user issues this command and is not priveleged (run- ning from user area 10 or greater, by default), then he will be asked for the System Password before the command is executed. If he is priveleged, CHDIR will execute the command without prompt. Examples: CHDIR C-DEV A5 chdir 1temp m0 chdir work b4 chdir sys1 a10 :Displaying the Directories The CHDIR command of the following form is used to display the names of the existing directories: CHDIR /DISPLAY Only the "/D" is required to complete the command; any characters following the "/D" are ignored. If the user is not priveleged, only the non-priveleged directories are displayed. If he is priveleged, all directories are displayed. A priveleged user is identified by the user number he is currently residing in (10 and above are priveleged by default). A count of the number of directory names defined and amount of directory space left for more names is given, and, if the user is not priveleged, the count of defined names may not match the number of displayed directory names since he is not permitted to see the names of the priveleged directories. :Setup Mode The CHDIR command of the following form places the user into Setup Mode: CHDIR /SETUP Only the "/S" is required to complete the command; any characters following the "/S" are ignored. Setup Mode is employed by a priveleged user to: 1) initialize the directory names 2) set/change the System Password 3) add/delete directory names 4) display the System Password and directory names 5) sort the directory names by disk/user area 6) save the current named directory structure to disk If the "CHDIR /SETUP" command is issued from a non- priveleged user area (user areas 0 to 9 by default), then the user will be prompted for the System Password. He is given 3 tries to get it right before CHDIR aborts (by default). Once in Setup Mode, the user is prompted with Setup Command (? for Help)? and Setup is waiting for the user to type a single-character command letter. If he types a ? or any other invalid command letter, he is presented with a summary of the Setup Mode com- mands. These commands are invoked by striking a single letter and case is not significant. A summary of these commands is: D -- Display System Password and Directory Names I -- Initialize and Clear All Directory Names N -- Create a New Directory Name P -- Set the System Password Q -- Quit without Updating S -- Sort Directory by Disk and User Number X -- Exit and Update CHDIR.COM on Disk Each command is explained on the following screens. D -- Display System Password and Directory Names This command prints three groups of information. They are: "System Password is ..." -- current setting for the System Password "Defined Directory Names -- du: name1 du: name2 du:name3 du:name4" -- disk, user area, and name for directories 4 entries are printed per line "n Directory Names Defined, Space Left for m More Names" -- number of names defined and space left I -- Initialize and Clear All Directory Names This command performs the following initializations: 1) the System Password is renamed to the default programmed value of the variable syspass; this name is initially "chdir" 2) all disk names, user areas, and directory name strings are initialized to zero The user is prompted with "Verify Initialization (Y/N)?" immediately after he strikes the letter I or i. If he replys with any letter other than Y or y, the message "Initialization Aborted" is printed and he is returned to Setup Command level. If he types a Y or y in response to this prompt, the initialization is performed and the message "All Directory Names Cleared" is printed. N -- Create a New Directory Name In response to this command, the message "System User Areas start at nn" is printed to remind the user where the priveleged user areas begin, and the user is placed into a loop, prompted with "Disk Letter and User (RETURN=Done or A-P 0-15)?" If the user wishes to create a new directory, he types one letter A-P (case is not significant) followed by a number in the range from 0 to 15. If the user does not wish to create a new directory, he strikes the RETURN key to abort to Setup Command level. N -- Create a New Directory Name, Continued If the user selected a valid disk/user combination, he is prompted with "Directory Name (RETURN = Delete Old Name)?" to which he may strike the RETURN key to delete the directory name previously associated with the disk/user specified or he may type a directory name (case is not significant and all lower-case letters are capitalized) to create a new directory or rename an old one. If the directory name or RETURN is accepted, the "Disk Letter and User" prompt will reappear to allow the user to continue creating directory names or abort to Setup Command level. N -- Create a New Directory Name, Continued Several error messages are possible while in this part of the Setup Mode. These messages are: "Invalid Disk Letter" -- Disk was not in the range from A to P "Invalid User Number" -- User Number was not in the range from 0 to 15 "Directory Name is too long -- Reenter" -- Entered directory name exceeded 8 characters "Error -- Directory Name Buffer Full" -- No more space is available in the internal buffer "Directory Name for ud: Deleted" -- (NOT an error message) Tells the user that a previously-defined name was deleted P -- Set the System Password This command in Setup Mode is immediately followed by the prompt "New System Password?" to which the user is allowed to enter up to 20 characters for his password. The user MUST enter a password; simply typing a RETURN sets the password to null and a simple RETURN is required for the new password when asked. Q -- Quit without Updating This command is answered with the prompt "Verify Abort (Y/N)?" to which the user replys with Y or y to abort Setup Mode and return to the operating system or any other character to return to Setup Mode. S -- Sort Directory by Disk and User Number This command causes the internal directory to be sorted by disk and user area. In response to this command, CHDIR sorts the directory (no informative prompt) and prints "Sort Complete" when done. This command is provided for the convenience of the user. X -- Exit and Update CHDIR.COM on Disk This command causes the prompt "Write New File (Y/N)?" to appear. If the user responds with anything other than Y or y, Setup Mode and CHDIR are aborted and control is returned to the operating system. If the user responds with Y or y, he is prompted with "Name of File (RETURN = CHDIR.COM)?" to which he may reply by striking the RETURN key to rewrite the file CHDIR.COM on disk or he may give another file name (the .COM is not necessary) to write a new file. The current directory structure is defined as a part of the written file, and it is used to access this new directory ala CHDIR commands. In entering the file name, case is not significant. X -- Exit and Update CHDIR.COM on Disk, Continued The prompt may vary if CHDIR has been rewritten under a different name. By default, the prompt is "Name of File (RETURN = CHDIR.COM)?" and, if, for instance, CHDIR was rewritten as CDIR.COM, the prompt from CDIR would be "Name of File (RETURN = CDIR.COM)?" Once the file name is specified or RETURN is struck, the following messages appear: "Sorting Directory by Disk and User Number" "Writing File CHDIR.COM to Disk ..." " File CHDIR.COM Written to Disk" An error message "Error -- Can't Create File CHDIR.COM" is possible, indicating that the disk or directory are full. Other Setup Mode Commands Striking any key other than those just described causes a built-in Help message to be displayed. Control is then returned to Setup Mode command level. :Planning a Directory Structure This section outlines a few comments and recommendations on a technique to combine ZCPR or ZMCPR with CHDIR to create a working environment. The ZCPR and ZMCPR command-search hierarchy frequently take the user down to user 0 on drive A before the invalid command error message is given. This directory is, effectively, the ROOT of the system, and this would be a good place to store the CHDIR.COM file. "ROOT" itself is a good name for A0, and by standardizing on this name, any user can place himself here as he moves between systems and see the standard command set. Since a command-search hierarchy is used under ZCPR and ZMCPR, this, in conjunction with CHDIR, can be used to create a hierarchial directory structure. The first CHDIR.COM that is encountered during a search is the one that is effective, so by placing a CHDIR.COM in the command-search path before the ROOT is encountered, directory subtrees can be formed. Let me illustrate this concept with the following diagram: CHDIR Directories Tree Disk A: User 0: CHDIR.COM (1)ROOT --> WORK Directories: A0: ROOT B0: WORK Disk B: User 0: CHDIR.COM Directories: A0: ROOT ROOT B0: C-ROOT B1: C-DEV C-DEV B2: C-PGMS B3: C-DOC (2)C-ROOT --> C-PGMS User 1: No CHDIR.COM C-DOC User 2: No CHDIR.COM User 3: CHDIR.COM Directories: B0: C-ROOT B3: C-DOC B4: COMPILER B5: PROGRAM C-ROOT User 4: No CHDIR.COM (3)C-DOC --> COMPILER User 5: No CHDIR.COM PROGRAM Using the normal ZCPR command-search hierarchy, which is current user/current disk to user 0/current disk to user 0/disk A, the following can be noted: A) tree (1) is seen from any user number on A: B) tree (2) is seen from any user number except 3 on B: C) tree (3) is seen from user 3 on B: As the reader can see, this is a very powerful concept. Let's say that you are logged into A0 and want to read the documentation on the C compiler. You would have to issue "CHDIR WORK" to enter the directory WORK on B:. Issuing "CHDIR /D" from here shows you in directory C-ROOT, and you now issue "CHDIR C- DOC" to enter the documentation branch of the tree. From here, you issue "CHDIR COMPILER" to enter the compiler documentation directory. Expressed as a tree, this is: Feel free to move back to the previous displays via the L command if this is not clear to you. ROOT ! C-ROOT (WORK) / ! \ C-DEV C-PGMS C-DOC / \ COMPILER PROGRAMS This is a simple type of tree structure as implemented above. CHDIR goes beyond this, tho, and allows as much as a star or ring structure as well, or any combination desired. One more step that CHDIR allows the user to take is with priveleged users. Now, directories can be hidden from normal users. Priveleged directories are set up like normal director- ies, and CHDIR is the program which enforces the security. Note that the USER command must be removed from the CPR for this to work. Using ZMCPR adds a capability of logging into a new direct- ory and automatically invoking a new command interpreter. The MENU.CCP file can be either a menu display or an executable program, and as an executable program, it is run every time control is returned to the CPR while the user is logged into the current directory. In this way, a whole new command processor can be introduced with each directory, and as the user moves from one directory to another, he may move from menu-driven displays to ZCPR-like command line processors to other processors at will. The capabilities and potential are amazing! Yet another change may be made to enhance the capabilities of CHDIR. This change involves modifying the command-search hierarchy to a new path. For example: Old Path: User Current/Disk Current User 0/Disk Current User 0/Disk A New Path: User Current/Disk Current User Current/Disk A User 0/Disk A This provides a new CHDIR environment in which utilities can be grouped into different directories on A and all the work done on B. When a command is issued, command search falls to a pro- ject utility area on A before falling to the ROOT. The differen- ces between these to paths can be illustrated as follows: Old Path: User Current/Disk Current User 0/Disk Current User 0/Disk A New Path: User Current/Disk Current User Current/Disk A User 0/Disk A ------ Old Path: Work Area --> Common Root Utilities --> ROOT New Path: Work Area --> Project Utilities --> ROOT Under the new path, different user areas on A can contain the utilties, say, associated with a particular language, such as user 1 for C, user 2 for PASCAL, etc. Then, the corresponding work areas on B would be user 1 for C work, user 2 for PASCAL work, etc. Now, when a command is issued, the move from C work to C compiler to ROOT or PASCAL work to PASCAL compiler to ROOT. As the reader can see, the possibilities are staggering. And this is just the beginning. I hope you enjoy using CHDIR with ZCPR and ZMCPR, and don't hesitate to experiment with the possibilities available by these combinations. Comments on these programs and any new ideas the reader has would be appreciated. Richard Conn