Windows Expert/Windows Expert.iso/windownt/pterm.zip/readme.now

Text File | 1993-06-17 | 31KB | 656 lines

                                  P T E R M

                         Paragon Terminal Application

                                for Windows NT

                                 Version 0.1b

                                18, June 1993




   What's Going on Here?
   =====================

      This is a beta of Paragon Terminal Application for Windows NT. What's
      so great about PTERM? Not much yet, but here is a list of features
      available so far:

         o  Fully threaded (6 so far), native Win32 application

         o  Auto Zmodem download/upload

         o  Fast ANSI (including color!) terminal emulation

         o  Console based for speed

      The other valuable feature of PTERM is that as far as I know it is
      the only Zmodem capable native, multi-threaded Win32 terminal
      application available. It won't be for long, but for now...

      Some glaring omissions:

         o  No Dialer!?!?!

         o  No user interface driven configuration

         o  No annoying "register me now, or die" messages and
            purposefully broken features.

         o  Many other things which you will likely go insane without (but
            hang in there, it is my intention to evolve PTERM).


   Why Would You Do Such a Thing?
   ==============================

      Some months back, I was asked to beta test a C++ based,
      multi-platform communications library from a company called Lookout
      Mountain Software (William Herrera, owner/author, BBS 719-545-8572).

      The best method I could think of for testing this package was to use
      it as the core of a terminal application -- and PTERM was born.

      William has been extremely sensitive to the problems I found and
      enhancements I suggested, and should be commended for authoring such
      a stable and comprehensive communications library, which is available
      for DOS, Windows, OS/2 and Windows NT. All of the file transfer
      protocol code (Zmodem/Ymodem/Xmodem) is Williams, and he has done an
      excellent job implementing them (sealink and telink are also included
      in the communications library, but not in PTERM -- Xmodem and Ymodem
      will be available in the next release of PTERM).


   I Didn't Do It, I Swear!
   ========================

      Every precaution has been taken to ensure the safe operation of PTERM
      in your Windows NT system. But, come'on, not only is this copy of
      PTERM in beta, but so is the current (March '93) build of NT, so
      obviously I cannot be held responsible for any damage done to your
      system (or psyche) by PTERM or any interaction involving PTERM. So
      all I can say is "I didn't do it!", so don't blame me!


   What Do I Need To Use Pterm?
   ============================

      You need an Intel based (Intel Inside sticker optional) PC running
      Windows NT (March '93 build or later), with at least one serial port
      and a modem attached to that port.

      If someone would like to send me a MIPS R4400 or DEC Alpha AXP, I
      will be glad to get PTERM up on those platforms as well <grin>.


   Alright, What Do You Want For This?
   ===================================

      The list of things I want would be much too large to include in this
      document, so you will have to settle for what I need.

      What I need, from you, is the following:

         o  Bug reports (there should be plenty)
         o  Suggestions (again, no shortage expected here either)

      So, please, please inundate me with this information, I promise I
      will consider anything submitted (but nothing not submitted).

      I can be reached via internet mail at:

         [e-mail]

      FIDOnet people, try netmail to UUCP at 1:1/31, first line of the
      message body:

         To: [e-mail]

      I plan on finding a reliable FIDOnet system here in town, and when I
      do I will post my FIDOnet address for netmail.

      For slowest response, choose snail-mail:

         Ron Cox
         Paragon Consulting Group
         4212 West Cactus STE 1110-229
         Phoenix, AZ  85029
         ATTN: PTERM


      If you are a Windows NT developer, and would like to contribute code
      to PTERM, let me know! Currently I have no plans to charge real money
      for PTERM, so you will get the same thing I do as far as that goes,
      nothing but recognition (we'll be lucky to get that!). Any code you
      contribute will become public domain, and may be distributed in the
      future (in source or object form) or used in other projects without
      restriction.


   Free? Something Must Be Broken!
   ================================

      Actually, yes. I am releasing this with a several known bugs, and I'm
      sure many more unknown bugs. I am of the belief that the bugs I know
      about will not significantly affect the operation. Some require bug
      fixes in NT or the SDK, others just require me to figure out what's
      going on. Here is a list of the bugs I know about:

         o  The first time (during a given run) an upload starts and the
            file selection dialog pops up, it does so behind the console
            window PTERM is running in. After the first time, and during the
            same run, the file selection dialog will pop up above the PTERM
            window as expected. I am working on getting this fixed.

         o  After each file of a Zmodem upload, there is a 15-20 second
            period where a sync with the host is attempted. During this
            period, there are usually several (3-5) timeout messages. The
            sync finally takes place, and the host usually accepts the
            transfer. This is irritating, and throws off the CPS rating,
            but seems to cause no other problems. I am working on getting
            this problem solved more than any other.

         o  Occasionally, when exiting PTERM, just before the console
            window goes away, you may see a brief message mentioning some
            runtime error. I have no idea what is causing this, but am
            investigating it. I tend to believe it is a problem in the
            current build of the NT runtime libraries. It does not seem to
            have any adverse side effects.

         o  As mentioned, PTERM supports ANSI terminal emulation.
            However, I was unable to find any definitive document on
            ANSI, so I am sure some sequences are not supported, and
            its possible ones I do support operate incorrectly. I have
            little or no problems with the BBS's I call (including a UNIX
            shell account with ansi emulation) around town. I believe that
            ANSI is a superset of VT-100/102, so PTERM may work with
            these emulations as well. If anyone has a detailed document on
            ANSI/VT-100/VT-102, please, please send it to me. It needs
            to be real detailed and complete (I already have various bits
            and pieces). Also, the emulation in PTERM is tuned for 9600 baud
            and higher, so you guys with the old 1200 and 2400 baud modems
            will notice that PTERM spits out blocks of characters, giving
            the output a somewhat jerky appearance. This can be minimized by
            having PTERM use the actual baud rate you expect to connect at
            (see configuration below).

         o  When PTERM is run in a console window without a scroll bar,
            characters in the last column do not always scroll. I believe
            this to be a bug in NT, but am investigating. In any case, the
            solution is simple, use the system menu/buffer size to change
            the lines in the buffer to be larger than the size of the
            window PTERM is running in, which adds a scrollbar to the
            window. Actually, this is convenient as it gives you a scroll
            back buffer. I typically run PTERM in a window whose buffer is
            1024 lines (although the window size is 80x25), giving me that
            much scroll back.

      Well, them's the major ones I have found so far. Please report others
      to me as necessary.


      Some 'features' to watch out for:

         o  Once PTERM quits, it closes the serial port, and if the modem on
            this serial port is currently connected to somewhere, that
            connection will be lost (since closing the serial port drops
            DTR). You may be able to prevent this by setting your modem to
            always hold DTR high, but this will have the side effect of
            preventing ALT-H from hanging up the connection.

         o  If there exists, in your download path, a file with the same
            name as one you are attempting to download, the transfer will be
            aborted. I apologize for this, and I will have a reasonable
            automatic rename mechanism available in the next release.

         o  PTERM has a lot of trouble with the ANSI codes coming from
            Maximus BBS software. I am working on getting this straight. It
            seems Maximus uses some strange (although probably completely
            legal) derivation of the cursor position command. I will get
            this fixed as soon as I can get a detailed document on ANSI
            emulation (and even better document on what the hell Maximus
            sends out for various sequences).


   I'm Getting Sleeeepy...
   =======================

      I know, I know... Luckily, there are not many configurable options
      (yet) in PTERM, so this won't take much longer.

      Currently, I have PTERM read its configuration from the environment.
      The following environment variables are supported:


         PTPORT

            Set to the integer value of the port you wish PTERM to use. I
            have tested ports 1 and 2, but PTERM should be able to use any
            port available (please let me know if you have problems in this
            area). Example:

               set PTPORT=1


         PTWORD

            Set to the integer value of the data word size to open the port
            with. Typically 7 or 8 data bits. Example:

               set PTWORD=8


         PTPARITY

            Set to the parity to open the port with. Supported values are:

               NONE
               EVEN
               ODD

            Example:

               set PTPARITY=NONE


         PTSTOP

            Number of stop bits to open the port with. Typically 1 or 2.
            Example:

               set PTSTOP=1


         PTBAUD

            Set to the baud rate to open the port at. Supported speeds are
            300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, and 115200.
            PTERM locks the baud rate of the port at the speed given, as is
            necessary with most modern modems.

            Example:

               set PTBAUD=38400


         PTDOWN

            Set to the path where downloaded files are to be placed.
            Example:

               set PTDOWN=e:\download


         PTAUTOZ

            If this variable is set to ANYTHING, auto Zmodem downloads and
            uploads will be enabled. To disable, make sure it is not in
            defined in the environment. Example(s):

               set PTAUTOZ=yes            Enables auto Zmodem
               set PTAUTOZ=               Disables auto Zmodem


      There you have it. Those are the available options for configuring
      PTERM.

      There is virtually no error checking done on configuration, so make
      sure you (as in your brain) go into debug mode if you have problems.

      Included in the archive with this document and PTERM.EXE, you should
      find a batch file called PT.CMD. This is the recommended method of
      starting PTERM.

      Place PT.CMD and PTERM.EXE in your path. Edit PT.CMD to set the
      environment variables appropriate to your system. To run PTERM, type
      PT from a command prompt. The batch file will set the environment
      variables, and start PTERM in its own console window. You can easily
      create multiple batch files to run multiple copies of PTERM each on a
      different port. This has worked for me with 2 ports simultaneously.
      The batch file approach has worked from NT's CMD.EXE as well as the
      4DOS for NT command interpreter replacement.

      PTERM can be placed in (and executed from) the program manager, and
      even has its own embedded icon (just like a real Windows program!).
      To insure that the environment is set up correctly, start the control
      panel 'System' applet, and at the bottom use the two edit boxes to
      appropriately define the variables described above. You will have to
      log off and and back on for these to take effect, and will need to
      set them for each user account.

      When using a batch enabled file transfer protocol (Zmodem), the file
      selection dialog box which pops up for an upload will allow you to
      select multiple files from any one directory, using the standard
      Windows mouse/key combinations for multi-select lists (i.e. CTRL-CLICK
      adds a file to the list, and try SHIFT-CLICK to extend the list to the
      current point).

      For batch uploading, if PTERM finds a file called FILESTO.UPL in the
      current directory (the directory you were in when you started PTERM),
      it expects this file to contain a list of files (full paths) to
      upload, and will attempt to do so. If PTERM finds this file, it will
      go straight to uploading, bypassing the file selection dialog.

      I am sure I have forgotten a whole bunch of information here, but
      this should be enough to get you off the ground.


   Can I Run it Now?
   =================

      Well... Ok...

      But, "Don't touch it, you'll break it..." (U.S. West T.V. ad)

      When you run PTERM, it will splat some information on the screen.
      First it will display the key bindings it recognizes, things like
      ALT-X to exit, PGDN to download, etc. Next, it displays the current
      settings as read in from the environment. Pressing F1 will display
      this information at anytime during the session.

      As mentioned, there is no dialer. This is too bad, I know, and will
      be one of the first things added.

      For those of you who have been spoiled all their lives by a dialer and
      do not know how to do it manually, if you have a modem which supports
      the Hayes command set (are there any which don't?) you can dial a
      number from PTERM like so:

         atdt555-5555               Tone dial 555-5555
         atdp555-5555               Pulse dial 555-5555 (yuck!)

      On my USR Sportster, the command

         a/

      executes the last command entered, and can be used to redial.


   Some Closing Thoughts
   =====================

      Its not much, but there it is. Please let me know of any problems or
      suggestions for enhancements you have.

      On my 386-33, running the March '93 beta, I have experienced excellent
      transfer speeds using the Zmodem in PTERM. On text files, at 14.4K
      with .v42bis (57.6K maximum), I have seen 3800+ cps. The same setup on
      compressed files yields 1650 cps and higher. If you have 16550's, and
      access to a FIFO enabled serial driver (I rebuilt it using the March
      DDK), install it! The serial driver for NT is absolutely solid, and
      extremely efficient. Before installing the FIFO enabled serial driver,
      during a 1650 cps download I would experience around 1700 interrupts
      per second (approx. one for each character), and during heavy
      multi-tasking characters were easily dropped.

      However, after rebuilding the serial driver (the 16550 support is in
      there, just not enabled -- The April update (and final retail build
      when it arrives) adds the ability to enable the FIFO's through the
      registry), with the same 1650 cps download I was getting around 200
      interrupts per second. This makes sense since I built the serial
      driver to enable the FIFO's to fire off an interrupt when they queued
      8 bytes, for an 8x decrease in interrupts. Subsequently, I have never
      seen PTERM drop a character in over 20 megs of file transfers.

      Another facet of the serial driver which operates well is RTS/CTS
      flow control. This is always turned on when PTERM runs, later it will
      be configurable. During heavy multi-tasking, RTS/CTS keeps the modem
      under control, holding it off when the serial buffer gets full. This
      has worked flawlessly.

      In closing, Windows NT has its problems, but all in all it is a
      solid, high performance operating system for the masses. I am
      confident in Microsofts (and mostly Dave Cutlers) ability to evolve
      NT, so much more is yet to come (MS: thanks sooo much for the console
      API, making all those UNIX utils that much easier to port!).

      Ron Cox
      Paragon Consulting Group


   Technically Speaking
   ====================

      Thought you were done, didn't you? Well, if you could care less about
      some of the technical details of PTERM, you are, else read on.

      As mentioned, PTERM makes full use of multi-threading. This stuff is a
      trip. It can make programming much more interesting (and in many cases
      greatly simplifies things!).

      There are 6 threads of execution, 5 secondary and the 1 main thread
      which all Win32 applications start with.

      The first two threads of interest are in Williams communications
      library. One is responsible for taking characters in from the serial
      port (actually, the serial driver) and placing them in a queue created
      by the library (the input queue) which is made visible to the user
      code. The second takes characters from another queue and writes them
      to the serial port (driver). The user code is responsible for placing
      characters to be sent out the port into this output queue, and does so
      through a set of 'Send' member functions.

      Also, both of Williams threads use overlapping (asynchronous) I/O,
      resulting in an even more efficient set up.

      Now for the threads I spawn. They are as follows:

         o  Input thread

            Because I did not want to muck with the input queue being
            managed by the communications library, I created another layer.
            My input thread simply waits for characters to appear in the
            main input queue, and block copies them into a local queue used
            by the display thread (below). If there are no characters
            waiting in the main input queue, this thread sleeps until there
            is (in the discussions which follow, this thread will be
            referred to as 'my input thread', to differentiate it from the
            main input thread operating in the library). It may be that I
            can increase PTERM's efficiency slightly by removing this layer
            and having the display thread pull characters directly from the
            library managed input queue -- something I will consider.


         o  Display thread

            This thread is solely responsible for removing characters from
            the local input queue (managed above) and deciding what to do
            with them. For instance, if the beginning of an ANSI escape
            sequence is detected this thread passes control to a function
            whose job it is to interpret the sequence (note: the ANSI code
            still executes within the display thread, no other thread has
            been created). One of the other jobs of the display thread is
            to optimize the output into the console window. This is done in
            a very simplistic manner. In the absence of ANSI escape
            sequences, the display thread will accumulate characters from
            the local input queue into a buffer -- up to 256. When the
            limit of 256 has been reached, or a special sequence is
            detected, the display thread blasts the buffer to the screen in
            a single call to WriteFile(). This is MUCH more efficient than
            calling something like putch() for each single character.
            However, at slow speeds (1200 and 2400 baud), it takes a
            noticeable amount of time to accumulate 256 characters, and
            this is the reason for the choppy display at these speeds. If
            you set the port to anything less than 9600 baud, PTERM reduces
            this 'blast' count to 64 characters, producing a smoother
            display.

            As if this wasn't enough, the display thread has one more job to
            perform. It watches for the tell-tale sequence of characters
            which signal the host is preparing for a Zmodem upload or
            download. If this sequence is found, it starts the appropriate
            code.

            If there are no characters in the local input queue, the display
            thread sleeps until there are.


         o  User thread

            The user threads job is pretty easy. If the user hits a key,
            decide what to do with it. Typically the key will be sent right
            out the port. If it is a control key sequence (like ALT-X), then
            the user thread executes the code appropriate for that key. This
            thread blocks on the keyboard, and as such sleeps when there are
            no characters available.


         o  Main thread

            The main thread is the first thread which executes (starting in
            main()). It initializes the port and other things, starts up the
            three threads above, and then goes to sleep waiting for all
            three of the threads above to terminate. At this point it wakes
            up and calls ExitProcess(), ending PTERM.


      Them's the threads, and a nice bunch of threads they are. However, if
      there is one thing I quickly learned from spawning threads all over
      the place, its that synchronization thingy.

      Here's the scenario: My input thread pulls characters from the main
      input queue to place in the local input queue. Fair enough. So, I
      start a Zmodem download. Boom! Of course, the Zmodem download code
      also wants to pull characters from the main input queue, so my thread
      fights with the Zmodem code. Remember, the Zmodem code is run as part
      of the display thread. So my input thread grabs some characters, then
      the Zmodem code [running in the display thread] grabs some
      characters, and so on. Zmodem will end up missing a bunch of
      characters it expected to see, and my input thread grab some
      characters from the transfer which the display thread will finally
      get and try to display. A mess...

      So, I need to find a way to synchronize the two threads. When Zmodem
      wants control of the main input queue, it needs to 'ask' for control
      from my input thread. Well, it really isn't as formal as all that.

      Just before my input thread grabs characters from the main input
      queue, it waits on a semaphore. Simplified, a semaphore is just an
      object which keeps count of how many threads have asked for control
      of it. When its count is 0, access is granted to the waiting thread.
      When a thread gets access to it, the semaphores count is incremented.
      Any other thread which waits on it goes to sleep until the semaphores
      count becomes 0 again. The count is decremented when a thread
      explicitly releases a semaphore, thus allowing another thread to gain
      access (this can get complicated when there are more than 2 threads).

      Ok, where were we? Oh, yes, my input thread waits on this semaphore
      gadget. Typically, it gets control instantly and drops into the main
      body of its code where it grabs characters from the main input queue
      and stuffs them in the local queue the display thread uses. Once it
      has transferred some characters, it releases the semaphore (and gives
      up the rest of its time slice). Its during the time between releasing
      the semaphore and waiting on it again that the file transfer code
      must act.

      The first line of code for a file transfer waits on the same
      semaphore. As soon as my input thread releases the semaphore, the file
      transfer code gets and holds access to it until the transfer is
      completed, thus preventing my input thread from mucking with the main
      input queue during the transfer. Whew!

      Being this is my first foray into threads, I am very interested to
      find out if my code breaks on a multi-processor machine. Does my code
      work now because it takes advantage of the synchronous behavior of a
      single processor? Interesting stuff, but I forgot to pick up my
      Sequent 16 processor monster-box at the grocery store the other day,
      so I suppose the answer will have to wait...

      I found one other interesting thing about Windows NT -- it seems to
      like to write data to the disk right away. Generally, this is a good
      thing, keeps your data safe. However, with Zmodem code writing 1K
      blocks to disk every .7 seconds or so (at 1650 cps), the disk access
      began to affect the performance of the download. The solution was
      easy, I just used a call to setvbuf() to create a memory buffer. The
      size I chose is 64K. So the system (C runtime) will accumulate 64K
      bytes from the fwrite()'s before writing to disk. Believe it or not,
      NT can actually write a 64K block to disk as quickly as a 1K block --
      difference is, now Zmodem only hits the disk one a minute or so (at
      1650 cps). Works great. Notice I said I made a 64K buffer. You 16 bit
      guys probably have (as I did) the signed integer maximum value
      memorized, 32K right? Well, under NT, a signed integer is 2^31, for a
      maximum [signed] value of 2 GB. So 64K was small compared to what
      I could make it.

      The file access areas of the transfer protocols are excellent
      candidates for overlapped I/O, probably doing away with the need for a
      write buffer. However, since Williams library is meant to be
      multi-platform, it is best to keep it as generic as possible. But,
      it is C++, and with proper inheritance the function responsible for
      writing data to disk could be overloaded (and William has isolated
      this operation for easy overloading!). A possible future enhancement
      to PTERM.

      One more technical note: PTERM does not change its base priority
      class, but it does manipulate the priority of several of its threads
      relative to the priority class it is started at. What? Ok, if you run
      PTERM from the command line like so:

         start pterm.exe

      then PTERM gets a base priority class of NORMAL. Using these commands:

         start /high pterm.exe
         start /realtime pterm.exe

      starts PTERM with a base priority class of HIGH or REALTIME
      respectively.

      Whats interesting is that when I started work on PTERM, I assumed I
      would need to have PTERM boost its base priority class to at least
      HIGH to make sure it could respond quick enough to bytes coming in
      over the port at high baud rates. This resulted in poor performance
      (dropping characters and such). So I assumed PTERM wasn't getting the
      priority necessary to keep up with bytes coming in the port. So, I
      pumped the base priority class up to REALTIME. The performance was
      even worse!

      Suddenly, it began to make sense. This is what I figure is happening:
      The serial driver itself probably runs at the upper end of NORMAL
      priority, or maybe even the lower end of HIGH priority. So I figure
      when I boosted the priority of PTERM to the same or above the priority
      of the serial driver, PTERM was stealing away time from the serial
      driver, causing the driver itself to drop characters!

      This is pure speculation, since I have no detailed knowledge of what
      priority the serial driver runs at. I assume there is a small part of
      the serial driver which is interrupt driven, and depending on the
      interrupt level it runs at, it can be preempted by other processes.
      I further assume that some other piece of the serial driver gets
      scheduled by the interrupt driven part above to remove characters from
      some small local buffer and place them in the buffer which ReadFile()
      uses. Again, this is pure speculation.

      At any rate, the interesting part is that when I changed PTERM to NOT
      change its base priority class, so that upon starting PTERM, it would
      default to the NORMAL priority class, performance was MUCH better!

      What does this tell me? The NT serial driver is incredibly efficient,
      yet can become sensitive to other high priority processes in the
      system (the behavior I described above was on my 386-33 -- this may not
      be an issue on faster machines, where higher priority processes might
      not have such adverse affects on the serial driver because the faster
      processor is able to juggle all the processes more efficiently).

      At any rate, what it means to you the user is that you are free to
      start PTERM at any of the 4 base priority classes, and your mileage
      may vary. Examples:

         start /idle pterm.exe
         start /normal pterm.exe
         start /high pterm.exe
         start /realtime pterm.exe

      I strongly recommend leaving it at NORMAL priority (by using the
      /normal switch, or not giving a priority at all). You are, of course,
      free to experiment.

      Well, the rest of PTERM is plain and boring (as if the preceding was
      not!). So not much else to say. Any specific questions? Feel free to
      contact me!