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UW/PC Version 2.01 Rhys Weatherley March 1991 1. INTRODUCTION This is version 2.01 of UW/PC, a multiple-window interface to UNIX for IBM-PC's and compatible computers. This program is based on a program written for the Macintosh by John Bruner. It provides up to seven separate login sessions on the remote UNIX machine, and requires the UW server to be running on the UNIX host. Before UW/PC can be used in a multiple session mode, the server must be compiled and installed on the UNIX machine. The source code for the server, together with the Macintosh program binaries can be found on many ftp archive sites. The standard server distribution is available in the directory "info-mac/unix" on "sumex-aim.standford.edu" [36.44.0.6]. The files are named "uw-42-part1.shar" ... "uw-42-part8.shar". In Australia, the UW server can be found in the directory "info-mac/unix" on "ditmela.mel.dit.csiro.au" [128.250.90.81]. A copy of the server source code without the Macintosh program binaries is included in this release. For those of you who have previously compiled the server, there has been no change at all to the server code. Version 2.01 of UW/PC is a total rewrite of the previous public release (1.05) in C++ to give a better program structure for the upcoming enhancements to UW/PC. Comments are invited to the author. This version implements the Unix Windows protocols 0 and 1. Protocol 2 (with more control over window management) is going to be supported in an upcoming Windows 3.0 version, however some small parts of Protocol 2 are present in this version which make Protocol 1 start faster. Protocol 2 is not fully supported in the DOS versions because of the complexity of the windowing code that is necessary. There are now many more configuration options, so even if you have used UW/PC before, I suggest that you read the section "CONFIGURING UW/PC" later in this documentation. If you wish to use the new ANSI terminal emulation option, then you should read the discussion on terminal types in the section "USING UW/PC" below. This version includes a terminal emulation compiler for creating new terminal types using a small assembly-code like language. It is described in the file TERMCC.DOC, but will not be required for most users - just those who want to write their own terminal types. UW/PC is distributed under the terms of the GNU General Public License (version 1), a copy of which is included. Note however that the server is NOT covered under this license and comes under the terms and conditions contained within its documentation. Also, please note that I am not affiliated with the Free Software Foundation in any way, and that further releases of this program may not have source code included or be distributed under the GNU General Public License, but probably will. Comments about UW/PC can be sent to the author at one of the following addresses: AARNet/Internet: rhys@cs.uq.oz.au Aust. Post: Rhys Weatherley 5 Horizon Drive Jamboree Heights QLD 4074 Australia Comments about the UW server for UNIX hosts should be sent to John Bruner: ARPANET/MILNET: jdb@mordor.s1.gov UUCP: {lll-crg,decwrl,caip}!mordor!jdb U.S. Mail: John Bruner Lawrence Livermore National Laboratory P.O. Box 5503, L-276 Livermore, CA 94550 2. FILES The following files should be present in the UW/PC distribution: COPYING A copy of the GNU General Public License. UW.EXE The actual UW/PC program itself. UW.DOC This documentation file. UWEG.CFG An example configuration file - rename to UW.CFG to use this file. TERMCC.EXE A compiler for creating new terminal types. TERMCC.DOC Documentation for TERMCC.EXE. SETMODE.COM A useful screen mode setting utility. HISTORY History of UW/PC versions. UW-SRC.ZIP The source code for UW/PC and TERMCC. UWSERVER.TAR The source code for the UNIX server. SETMODE was included to assist with configuration of the screen colours (see "CONFIGURING UW/PC" later). The Macintosh binaries have been stripped from the server, and can be obtained from one of the FTP sites mentioned above if desired. The source code in UWSERVER.TAR should be compiled on the UNIX host to allow the full multi-window potential of UW/PC to be used. 3. READ THIS IF YOU ARE HAVING TROUBLE If you are having trouble getting UW/PC to go, especially with the UW server program, then exit UW/PC and start it again with the "-debug" option. i.e. "uw -debug". Then, every character that is sent from the remote machine will be placed into the file "UWDEBUG.OUT" in the current directory. Upload this file to the UNIX machine in binary mode (in some way), uuencode it and send it to me via e-mail. This will help me to know EXACTLY what you are doing, and so I may be able to find the bugs more easily. On some systems, the server will abort when it is started with a message like "no ttys". If this happens, recompile the server after modifying the Makefile to compile using BSD4.2 instead of BSD4.3 and play with the compilation options. This is discussed in the Makefile for the server. 4. USING UW/PC When UW/PC starts, it initialises the screen and serial port, and then enters "Protocol 0", which is equivalent to the dumb terminal emulations available in conventional communications programs. The default emulation is ADM31, but VT52 and ANSI emulations are also available. A number of special keystrokes are defined in protocol 0: ALT-B - Send a line break over the serial link. CTRL-BREAK and CTRL-END will also send a line break. ALT-C - Start a "cut" operation. You can select a region in the current window to cut and place in the clipboard. Press RETURN at each corner and ESC to quit. You can also use the mouse to select a region of the current window. Press down and hold the left mouse button at one corner of the region and release it at the other corner. This will only work if the mouse is enabled. See "CONFIGURING UW/PC" below. ALT-D - Send the string defined by the "dial" configuration variable to the modem. See "CONFIGURING UW/PC" below. ALT-H - Hangup the modem, by first dropping the DTR signal, and then sending the hangup string if the carrier signal is still present. ALT-I - Send the modem initialisation string, even if a carrier signal is present. ALT-J - Jump to a DOS shell. Type "EXIT" at the DOS prompt to return to UW/PC. ALT-L - Start and stop an ASCII capture. You will be prompted for a file name to store all data coming from the remote host in until you press ALT-L again. If you have the status line set to display the terminal type then it will change to "CAP" while the capture is in effect. ALT-P - Paste the contents of the clipboard into the current window. If a paste is currently active in another window then the paste will be ignored. After every line is sent to the remote host a 10ms pause will be made to allow the remote host to catch up. You can also press the right mouse button to start a paste if the mouse is enabled. ALT-R - Receive a file from the remote host. See UPLOADS AND DOWNLOADS below. ALT-S - Send the contents of a file to the remote host. See UPLOADS AND DOWNLOADS below. ALT-T - Send a string of the form "stty rows N columns M" to the remote host. This is useful for resetting the remote host's idea of what the current window size is. Sometimes Unix systems get confused as to the size of a terminal type (usually 80x24 in UW/PC), and so this command will send an "stty" command-line to correct it. ALT-U - Send the string defined by the "uw" configuration variable. This is useful once connected to start the UW server on the UNIX host. See "CONFIGURING UW/PC" below. ALT-X - Exit the program. If any windows are present, they will be destroyed. This function does NOT hangup the modem before exiting, so UW/PC can be restarted in protocol 0 and connected to the remote host if required. ALT-Q - Quit the program: same as ALT-X. ALT-Z - Popup a small box containing descriptions of the special keystrokes. Press any key to resume. Protocol 0 exists to allow you to connect to the UNIX host in whatever way the host requires. When you are ready to use the multi-window mode of UW/PC, execute the UW server on the remote host by typing its command name, or by pressing ALT-U if the "uw" configuration variable has been set correctly (see below). Note that the server must be compiled and accessible for you to do this. The UW server sends a special control sequence which UW/PC interprets and then automatically starts the multi-window session. By default the server will also create a terminal window. See the documentation that accompanies the server for information on modifying its startup behaviour. Once UW/PC has entered the multi-window session (protocol 1), up to 7 windows can be created, ALT-U no longer has any effect, and the following additional special keystrokes are defined: ALT-E - Exit the UW session and return to protocol 0. A "kill window" request will be sent for all currently active windows. ALT-K - Kill the current window. ALT-N - Create a new window if possible. Up to 7 windows may be created and used. The status line will indicate which windows are currently active if you have set it correctly. (See "CONFIGURING UW/PC" below). ALT-W - Cycle to the next window. e.g. if you are in window 3, then you will cycle to the next highest numbered window, cycling back to 1 if necessary. This is useful to quickly switch between windows. ALT-0 may also be used for this. ALT-n - "n" is a digit between 1 and 7. These keystrokes direct UW/PC to "jump" to the nominated window. Usually, if you exit a UNIX shell in a window, that window will be killed automatically, and when all windows have been killed, the UW session will terminate, returning you to protocol 0. If protocol 1 does not exit, then you can try some of the procedures given in the "LIMITATIONS" section later in this document. The UW server usually defaults to using ADM31 emulation whenever it creates a new window. You may need to manually modify the UNIX terminal type in the windows to get the correct screen behaviour if you have set your default emulation type to something other than ADM31 in the configuration file. If you are using the Korn shell "ksh", you can add the following lines to your ".kshrc" file to automatically change the terminal type to XXX, where XXX is your preferred terminal type. case $TERM in adm31) TERM=XXX export TERM ;; *) ;; esac Some UNIX termcap entries do not have the entry for the ADM31 terminal type, and so some UNIX programs may not have the correct screen behaviour. The UW server will set the TERMCAP environment variable within a UW session window, but in protocol 0 this environment variable is not set automatically. To use ADM31 emulation in protocol 0 on machines without the correct termcap entry, set the TERMCAP environment variable to the following string (newlines are for layout only, and shouldn't appear in the actual value): adm31:cr=^M:do=^J:nl=^J:al=\EE:am:le=^H:bs:ce=\ET: cm=\E=%+ %+ :cl=^Z:cd=\EY:co#80:dc=\EW:dl=\ER: ei=\Er:ho=^^:im=\Eq:li#24:mi:nd=^L:up=^K:MT:km:so=\EG1:se=\EG0: Alternatively, setting the "emul0" configuration variable to "vt52" or "ansi" will allow you to use VT52 or ANSI emulation in protocol 0, which are usually defined in all termcap and terminfo entries. ADM31 emulation will still be used for UW session windows if the "emul" variable is set to "adm31". ADM31 emulation is much "smarter" than VT52, so you will probably want to use it wherever possible. ANSI emulation is also available and this is much smarter than ADM31, but because the UW server defaults to ADM31, you may still want to use it instead of ANSI. If you do want to use the ANSI emulation mode and the "ansi" termcap on your Unix host is "brain-dead" (i.e. it doesn't support very much), then you can set the TERMCAP variable to the following value to get a smarter ANSI emulation: ansi:am:bs:pt:co#80:li#24:kn#3: :AL=\E[%dL:DL=\E[%dM:DO=\E[%dB:IC=\E[%d@:LE=\E[%dD: :RI=\E[%dC:UP=\E[%dA:al=\E[L:bt=\E[Z:cd=\E[J:ce=\E[K: :cl=\E[H\E[J:cm=\E[%i%d;%dH:ct=\E[2g: :dc=\E[P:dl=\E[M:ho=\E[H:ic=\E[@:kb=\b:kd=\E[B: :kh=\E[H:kl=\E[D:kr=\E[C:ku=\E[A:nd=\E[C: :se=\E[m:so=\E[7m:st=\EH:ue=\E[m:up=\E[A:us=\E[4m: :k1=\EOP:k2=\EOQ:k3=\EOR:k4=\EOS: To find out if the "ansi" termcap on your computer is "brain-dead", search the file "/etc/termcap" on the Unix host for the string "|ansi|" and if it only has a couple of lines listed before the next entry, then it is "brain-dead". If there are 5 or more lines, then most likely your "ansi" termcap is OK. Ask a local guru if you are unsure. TERMCAP and TERMINFO gurus may want to play around with the various ANSI, VT100 and VT102 compatible terminal types, etc to try and find something that has lots of features for working with editors such as emacs, etc. See the ANSI.CAP file in the source archive and the documentation for TERMCC for more information on the capabilities of UW/PC's ANSI emulation. Any suggestions (no matter how nasty :-) on the ANSI emulation are welcome. Adding the following lines to your ".kshrc" file is the best way to make sure that ANSI emulation is always correctly used in Protocol 1. You can also use ANSI emulation in Protocol 0 if you desire. case $TERM in adm31) TERM=ansi export TERM ;; *) ;; esac TERMCAP='ansi: *** the ANSI string given above *** ' export TERMCAP All of the special protocol 0 keystrokes except ALT-U also work in protocol 1, but it is inadvisable to use ALT-I during a UW session. ALT-H will still hangup the modem, after exiting the UW session. ALT-B will first exit any active UW session before sending the BREAK pulse. This avoids some strange things that may occur with network terminal servers and the like. ALT-X will also terminate a UW session before exiting UW/PC. 5. UPLOADS AND DOWNLOADS UW/PC has ASCII and XMODEM file transfers built-in and it can also use the program DSZ (which you need to obtain separately) to perform ZMODEM transfers. ZMODEM file transfers are disabled in protocol 1 (the multi-window mode) because DSZ is incompatible with the UW protocol. It should be noted however, that because of deficencies in the UW server, you probably won't be able to run more than one XMODEM transfer at the same time. This stems from the fact that if a lot of input or output is appearing in one window then all other windows will grind to a halt. Except in the case of a ZMODEM receive, you will be prompted for the filename of the file to be transfered. To use DSZ for ZMODEM transfers, you will need to have DSZ.COM somewhere in your PATH for it to be accessible. Note that the DSZ command "ALT-N" will allow you to "nuke" a transfer and return to UW/PC if something goes wrong. ASCII uploads will the send the contents of the text file to the remote machine, pausing 10 milliseconds between lines to allow the remote machine to catch up. You need to make provisions for capturing the data at the other end. Usually you can do this by executing the UNIX command "cat >filename" before you start the transfer, where "filename" is the file you want the data to end up in. Once the transfer is complete, you can press CTRL-D to end the "cat" command's processing. Pressing ESC will abort the transfer - all other keys will be processed as normal. ASCII downloads consist of placing all incoming data from the remote host into the nominated file. Pressing ESC will abort the transfer, and all other keys are processed as normal. Usually you type in "cat filename" at the UNIX command line (but don't press RETURN yet), start the ASCII download, and then press RETURN to start it going. Once it has finished you press ESC to abort the reception of characters. ASCII capture (ALT-L) is similar to ASCII download, except ALT-L is used to abort the transfer. For XMODEM and ZMODEM transfers, you will need the "sx", "rx", "sz" and "rz" programs for UNIX compiled and available. Read the manuals for these programs to get more information on their options. For downloads, start the "sx" or "sz" programs on the remote machine and then press "ALT-R" to start the reception of the files. Note that unlike some other communications programs, the ZMODEM "auto-download-start" command sequence is not recognised, and so you need to manually start the download. For uploads, start the "rx" or "rz" programs on the remote machine and then press "ALT-S" to the start sending the nominated files. In the near future, UW/PC will be upgraded with a mini-FTP protocol that will allow you to transfer files between the remote machine and your PC using FTP-like commands. This protocol will be more "aware" of the problems of performing multiple transfers when more than one window is active and will get around some other problems with transmission mediums that do not accept some characters. 6. USING UW/PC WITH OTHER PROGRAMS UW/PC can be used as a stand-alone communciations program, or in conjunction with some other communciations program. If you have a faviourite communications program (e.g. Telix, Procomm, MS-Kermit, etc), and have extensive "scripts", etc to connect you to a UNIX host, and still want to use these functions, you can still do so. Once connected to the UNIX host (or whenever you are ready), you can shell out to a DOS shell (a function available in most programs), and execute UW/PC to handle the UW sessions. Note that you must execute the UW server from within the control of UW/PC otherwise the startup control sequence that the server sends to UW/PC may be missed. You can exit UW/PC at any time to return to the other program. It may also be possible for your program's scripting language to automatically execute the UW/PC program once a UNIX host connection has been made. 7. CONFIGURING UW/PC When UW/PC starts up, it first inspects the file "UW.CFG" in the current directory, and if that doesn't exist, the file "UW.CFG" in the directory the program was loaded from. This plain ASCII text file is expected to contain configuration parameters for UW/PC. If it is not found, defaults will be chosen for all parameters. An example configuration file is distributed with UW/PC. Each line of the file is of the form "name=arg" where "name" is the name of the configurable parameter, and "arg" is its argument. Comments may be introduced starting with "#", but may not appear within commands. The configurable parameters, which are all optional, and their defaults follow: address (defaults are the normal COM port addresses) This option allows you to change the hardware port address to use for communication on the port specified by the "port" configuration option. This option's value can be specified in decimal, octal (prefixed with '0') or hexadecimal (prefixed with '0x') and should appear after the "port" option if that is supplied. The defaults for each of the four COM ports are 0x3F8, 0x2F8, 0x3E8 and 0x2E8 respectively. baud (default 2400) The baud rate to use for transmission. This can be one of 110, 150, 300, 600, 1200, 2400, 4800, 9600, 19200, 38400 or 57600. beep (default on) Enable or disable the terminal beep. This can be either on or off. bits (default 8) The number of data bits (7 or 8) to use for transmission. cinit (default yes) Indicates whether or not the initialisation string should be sent if the carrier already exists. This can be either yes or no. When using UW/PC with other programs (see above), it is useful to set this to "no" to prevent the initialisation string being sent to the UNIX host once connected. colhighlight (default is screen mode dependent) This numeric option specifies the screen attribute to use for the highlighted printing characters (e.g. bold). Setting this to 0 will make UW/PC use the default attribute which depends on the screen mode in use. colhighstatus (default is screen mode dependent) This numeric option specifies the screen attribute to use for the highlighted printing characters on the status line. Setting this to 0 will make UW/PC use the default attribute which depends on the screen mode in use. colinverse (default is screen mode dependent) This numeric option specifies the screen attribute to use for the inverse printing characters. Setting this to 0 will make UW/PC use the default attribute which depends on the screen mode in use. colnormal (default is screen mode dependent) This numeric option specifies the screen attribute to use for the normal printing characters. Setting this to 0 will make UW/PC use the default attribute which depends on the screen mode in use. colstatus (default is screen mode dependent) This numeric option specifies the screen attribute to use for the normal printing characters on the status line. Setting this to 0 will make UW/PC use the default attribute which depends on the screen mode in use. cursor (default is underline) This option specifies the shape of the cursor to be used on the screen. It can be underline, halfheight or fullheight. This is very useful if you run UW/PC in a DOS window in Windows 3.0 386 enhanced mode because the underline cursor is very hard to see. dial (default "ATDT") This string is sent to the modem when ALT-D is pressed, as a shortcut for dialing. You can modify this string to contain a phone number if you wish. e.g. "ATDP1234567^M" will dial the number 1234567 using pulse dialing on a Hayes compatible modem when ALT-D is pressed. The string cannot be longer than 100 characters in length. disable (default no) This option allows you to completely turn off the handling of the special UW server codes that UW/PC processes. This allows you to use UW/PC as a completely stand-alone comms program with no interference from the UW protocol. This option can be either yes or no. Note that you cannot use the multi-window mode of UW/PC if this is set to 'yes'. emul (default adm31) The default terminal emulation type to use for windows. When a new window is created, it will use this emulation type. This can be one of adm31, vt52, or ansi or a string (e.g. "vt102"), signifying a currently loaded terminal description that will be searched for to become the default emulation. The double quotes are optional. When the terminal description is searched for, case is ignored during compares. emul0 (defaults to whatever emul is set to) Set the terminal emulation type for protocol 0. This is to rectify some problems with UNIX termcap entries that are missing the entry for ADM31 terminals, as discussed above under "USING UW/PC". It can be one of adm31, vt52 or ansi or a string specifying a terminal type loaded with the "terminal" configuration option. F1 - F10 (default undefined) These ten configuration variables allow you to define the function keys to any strings you desire. If you do not define a function key, it will have its default setting as defined by the terminal emulation in use. The character "^" is a control code prefix. e.g. "^M" corresponds to the CTRL-M character. "~" indicates a 1/2 second pause and "#" outputs the next character directly, so that "#^" is the character "^" ("#~" and "##" are similar), EXCEPT when the next character is alphabetic. In that case, if the character is "x", then ALT-x is taken as the next character. In this way, you could define F10 to "#Xy" to always exit UW/PC without needing to answer the Yes/No question. Defining a function key to an empty string will also cause the default behaviour to be taken. The strings cannot be longer than 100 characters in length. font (default "System") Set the font facename to be used in the Windows 3.0 version of UW/PC. This can be up to 15 characters in length. fontsize (default 8) Set the size of the font to be used in the Windows 3.0 version. init (default "ATZ^M~~~AT S7=45 S0=0 V1 X1^M~") The modem initialisation string, delimited by double quote characters. The strings are the same as for function keys, except that ALT sequences are ignored. The string cannot be longer than 100 characters in length. hangup (default "~~~+++~~~ATH0^M") The modem hangup string to use if after dropping the DTR signal, the carrier is still present. The string cannot be longer than 100 characters in length. mouse (default on) If this configuration option is on then the mouse will be enabled for use by the internal routines. In particular, cutting and pasting can be done using the mouse (as well as the keyboard). This option has no effect if no mouse was found attached to the computer or it could not be initialised properly. Only Microsoft-compatible mice are supported by UW/PC. You may want to set this to "off" even if you have a mouse because the mouse processing can slow down UW/PC's screen updating considerably. parity (default none) The parity to use for transmission. This can be one of none, even or odd. popup (default is off) This option specifies whether or not windows created by the remote host should automatically popup to be the top-most window when they are created, so that they can then be used straight away without you needing to determine their window numbers. This option can be either on or off. port (default 1) The serial port to be used for communications. This can be one of 1,2,3 or 4. sformat (default " ALT-Z for Help %v %e %v %p %v %u %v Windows: %a") Set the format of the status line when it is enabled by the "status" configuration option. This string cannot be longer than 100 characters in length. The string can contain "printf"-style commands to make various types of information appear in the line. When the status line is displyed on the screen, it is truncated to the screen width. The commands are summarised below: %% - The character "%" itself. %a - Expands to all currently active window numbers separated by spaces. This will always occupy 14 characters, padded with spaces. The current window is highlighted. %e - Terminal type of the current window, padded to fill 5 characters with spaces. %h - Turn highlighting on (alternate attribute). %i - Turn highlighting off (normal attribute). %n - Expands to the highest numbered window in use at present ('0' if in Protocol 0). %o - Expands to "Online " or "Offline" depending on the current communications carrier status. %p - The current serial communications parameters. e.g. "COM1 2400 N-8-1". %s - Current system time in 24-hour format (HH:MM). %t - Elapsed time since logon in hours and minutes, or 5 spaces if no carrier is present. %u - In protocol 0, gives two spaces and in protocol 1, gives the string "UW". %v - Draw a vertical line in the status line. %w - Current window number ('0' if in protocol 0). %0-%9 - These are used internally by UW/PC for showing block counts on file transfers, etc. If you use them in your status line, they will expand out to the string "0". sposn (default left) This option specifies where the status line specified by the "sformat" option is to appear on the bottom line of the screen. This can be one of left, right, center, centre, leftsquash, rightsquash, centersquash or centresquash. The values that specify squashing will make the line appear in the given position using up only as many character positions as necessary. The rest of the line will be set to black and white. This is useful for very small status lines - they can be squashed into a corner of the screen and effectively ignored. status (default on) Enable or disable the status line on the bottom of the screen. This can be either on or off. stop (default 1) The number of stop bits (1 or 2) to use for transmission. strip (default off) Enable or disable the stripping of the most significant bit of received characters. This can be either on or off. This is provided to strip unwanted parities on some systems. If seven bit transmission is in use, this option will be ignored and the most significant bit will always be stripped. swapbs (default off) Enable or disable the swapping of the backspace and delete keys. Some people like to have this swap in place. This can be either on or off. terminal (no default) This can appear up to five times in the configuration file and each occurrence will load a terminal description into memory. It's string value specifies a filename for a compiled terminal description. The full pathname should be supplied. For example, the following line could be added to the configuration file to add a "VT102" terminal emulation: terminal="c:\uw\vt102.trm" The standard VT52, ADM31 and ANSI terminal types can be replaced with new terminal descriptions by loading new files that have the VT52, ADM31 or ANSI terminal type specified. uw (default "uw^M") This string is sent to the UNIX host in protocol 0 when the ALT-U key is pressed. Its purpose is to send the name of the UW server program to the host to start the server, and thus is a shortcut to typing the name in by hand. The characters "^" and "~" have the same meaning as for the modem control strings. The string cannot be longer than 100 characters in length. xonxoff (default encoded) This configuration variable specifies whether or not the XON (CTRL-Q) and XOFF (CTRL-S) keys should be encoded for transmission to a UW session, or sent direct without any encoding. This can be one of direct or encoded. On some systems, the modem connection is routed through a "terminal server" which exists on the UNIX host's network. Some of these terminal servers provide independent XON/XOFF flow control, and process the XON and XOFF characters themselves. When the XON and XOFF characters are encoded however, they are passed through to the actual UW session, but because of the high level of buffering within the UW server, they are practically useless to stop and start the display. By setting this variable to "direct", the terminal server will receive the XON and XOFF characters, giving better control over scrolling displays. zmodem (default "DSZ") This configuration variable specifies the name of the program to run to perform ZModem file transfers. Normally the full path is searched for "DSZ" but you can specify a more fuller path in this variable (e.g. "c:\bin\dsz") if you wish. It is assumed that the program indicated by this variable has the same command-line syntax as the DSZ program from Omen Technology Inc. Strange things may occur if the command-line syntax is not identical. This string may be up to 100 characters in length. On startup, UW/PC makes a choice of screen colours based on the current screen mode. If the current mode is 0 (40x25 CGA mono), 2 (80x25 CGA mono) or 7 (80x25 MDA mono), a monochrome scheme will be chosen. Otherwise, a colour scheme will be chosen. These colours are overridden by the settings of the "colXXXXX" configuration options in the configuration file. The utility program SETMODE.COM is provided to help out with setting screen modes and the default colours. It takes a one-character argument corresponding to the mode to set. e.g. "SETMODE 3" or "SETMODE 2". There must only be ONE space between the command-name and the one-character argument, since the command is very primitive, but effective. An 80x25 screen mode will always be used regardless of the current screen size. 8. LIMITATIONS UW/PC and the UW server have a number of limitations. Primarily, if a large amount of output is appearing in one window, the UW server will be slow to process input and output in another. This is a limitation of the UW server, and not UW/PC. The second limitation is unavoidable. With all serial communciations over telephone and other serial links, errors in transmission are likely to occur. The UW protocols have no provision for error-free transmission of information, and especially the special UW commands that are sent back and forth between UW/PC and the UW server are not sent using an error-free transmission. If errors occur in the transmission of these commands, strange things like output appearing in the wrong windows may result. Since the UW commands are fairly rare (usually only when swapping windows for input or output), and the chances of normal data being corrupted into legal UW commands are very small, very few problems should result on reasonably clean modem connections. As a last resort, you can press ALT-E to return to protocol 0, and if the UW server hasn't exited (because the exit command was corrupted), you can press (while in protocol 0, not protocol 1) "CTRL-A" followed by the "Delete" key (or the backspace key if the "swapbs" configuration option is set to "on"), which corresponds to the UW exit command, which should abort the UW server. 9. FUTURE WORK In future, UW/PC will be extended with the following capabilities: A mini-FTP protocol, scroll-back buffers, Ymodem file transfers in any window (and also protocol 0), XON/XOFF flow control and support for a subset of the UW protocol 2 features which gives more control over window management. Comments and suggestions are very welcome. A major project that is underway is a port to Windows 3.0.