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File KERMIT.BWR MS-DOS KERMIT 3.0 "BEWARE FILE" January 1990 Last update: Wed Jan 24 19:30:31 1990 This file lists limitations, restrictions, and known bugs in MS-DOS Kermit version 3.0. Also see KERMIT.UPD for a list of new features of version 3.0 and incompatibilities with older releases. The user manual for MS-DOS Kermit 3.0 is "Using MS-DOS Kermit", by Christine M. Gianone, published by Digital Press, Bedford, MA, 1990, order number EY-C204E-DP. Call 1-800-343-8321 (toll free, USA) to order. The technical reference by Professor Joe R. Doupnik is in preparation. MS-DOS Kermit 3.0 has been successfully tested with PC-DOS 2.0, 3.0, 3.30, and 4.0 on a wide variety of IBM PCs, XTs, PC/ATs, Portable PCs, PS/2s, and compatibles. DOS 2.0 or later is required, plus at least 130-140K of free memory. LIMITATIONS AND RESTRICTIONS OF MS-DOS KERMIT On IBM PCs and PS/2s with IBM asynchronous adapters, Kermit can be used at speeds up to 57600 bps. For 115200 bps to work, a very short shielded cable is required, and the async adapters of the two machines must be in perfect tune. It's an electrical affair, not one of programming. Although high speeds can be used for file transfer, the maximum speed for VT and Tektronix terminal emulation depends upon the model of your PC. For original PCs and PC/XTs, it is 9600 bps. For PC/ATs and PS/2s, it is generally 19200, perhaps 38400 for the faster 386-based models. If your speed is set too high for your PC model, the symptom will be lost or garbled characters (or graphics images) on the screen. MS-DOS Kermit does not attempt to monitor the communication line for carrier loss during terminal emulation or file transfer (but you can SHOW MODEM or SHOW COMMUNICATIONS to inquire about CD, DSR, and CTS). The absence of carrier monitoring is a design decision. Interactive users will notice when carrier drops, and timeouts will catch the situation during file transfer or script execution. The script command WAIT permits sensing carrier presence while doing scripts or macros. The benefits are not having to wire a direct RS-232 connection to simulate a modem's carrier being present, and being able to talk to the local modem before carrier is detected from the other modem. The SHOW MODEM and WAIT commands will work right only if your modem or other communication device is configured to raise and lower the DSR, CTS, and CD signals appropriately, and the cable that connects your PC to the modem passes these signals through. For some modems, the factory setting is to always keep CD on, even if there is no connection. Consult your modem manual. For RS-232 devices, the HANGUP command (and Ctrl-]H in CONNECT mode) will work only if the cable that connects your PC to the communication device passes the DTR signal through, and if the communication device itself is configured to hang up or otherwise terminate the connection when the DTR signal is lowered by the PC. For some modems, the factory setting is to ignore DTR transitions. Consult your modem manual. MS-DOS Kermit will not necessarily work with all brands of internal modems, particularly some of the built-in ones that come with laptop PCs from various makers. If you cannot communicate satisfactorily through such a modem, give the command SET PORT BIOSx (where x is 1, 2, 3, or 4, corresponding to whether the modem is COM1, COM2, COM3, or COM4) and try again. Kermit does work with most popular brands of internal modem (such as the Hayes Smartmodem 1200B and 2400B), and with all known external modems, both direct-connect and acoustic. Kermit does not work properly with revision C of the built-in modem in the Toshiba T1600 laptop computer, due to an idiosyncracy of this modem. The symptom is that the connection drops when you escape back from connect mode, at which point Kermit turns off interrupts. The modem misinterprets this as a command to hang up the phone and turn itself off. Revision F of this modem does not have this problem. Note: This problem occurs with the "built-in" modem, not the "internal" modem (these are two different devices). The IBM PC implementation of VT300/100 emulation has several restrictions: no smooth scroll, no ENQ/Answerback, no setup screen (use SET TERMINAL commands instead), no split speeds. Double height/width characters are simulated. In addition, the VT320/340 emulator lacks the following functions of the corresponding real terminals: . Down loadable soft fonts . ReGis graphics (VT340/330) . Dual sessions in split screens (VT340/330) . Local screen editing and block transmission (for security reasons) . Answerback (also for security reasons) . Selective erasure (as a character attribute, a formatted screen item) . And many of the exotic and rarely known features of the DEC VT340/330 series: mostly formatted screen and graphics operations highly specialized to DEC hardware. When you type the escape character (normally Ctrl-]) while in Tektronix graphics mode, the screen goes back to text memory. Then when you type the argument character, the graphics screen reappears (unless the argument was C or P). Ctrl-]F will not file the graphics screen, but rather the text screen, because that's the screen that's showing after type the Ctrl-] key. To file the graphics screen (in TIFF format), use Ctrl-End (which has the Kermit verb \Kdump assigned to it by default). When printing a graphics screen to a black-and-white printer, make sure your graphics image has a black background. Otherwise you are likely to get a solid black printout, since most graphics printer drivers print a black dot for every dot that's illuminated on the screen. If your display adapter lacks sufficient memory (as do CGA and the early 64K EGA boards), then when you toggle away from a graphics screen, or type the connect-mode escape character (Ctrl-]), the graphics image will be lost. Furthermore, certain graphics images may be overlaid with vertical stripes on small (64K) EGA systems. In VT100/300 emulation on the IBM family, receipt of the ESC [ 4 m (turn on underscore) command results in reverse video rather than underscore on IBM CGA, EGA and other color monitors. This was done to avoid showing underscoring as the IBM specification of non-bold blue on black. If a file is sent to the PC, and MS-DOS Kermit has SET FILE WARNING OFF (meaning, overwrite existing files when incoming files arrive with the same name), and the sender reports the file size in an Attribute packet, and this size is larger than the available disk space on the PC, then MS-DOS Kermit will properly refuse the file, but will also destroy any previously existing file of the same name. SET DEST DISK does not redirect output of REMOTE commands to disk -- they come to the screen, by design. Use the ">" output redirection symbol for this, for example: "remote dir > files.dir". The name and password that you specify in SET SERVER LOGIN must be matched exactly by the ones in REMOTE LOGIN. Alphabetic case matters. It can be very difficult sometimes to interrupt execution of a script from the keyboard by typing Ctrl-C. Particularly scripts with INPUT commands that have long timeouts, within loops, etc. If you think your script needs to be manually interrupted at critical points, you can use the following trick: SET ALARM 3 ECHO Type something now if you want to quit...\13 PAUSE 3 IF NOT ALARM STOP This works because PAUSE is interruptable by any keyboard input. The last line of a TAKE command file (or MSKERMIT.INI) must end with a carriage-return/linefeed sequence (like all the other lines in the file), or it might not be processed by the program. Commands in TAKE-files or MSKERMIT.INI can be continued by including "-" as the last character on the line, but NOT if the line ends with a trailing comment. In other words, you can't have a trailing comment on a continued line. If you need to end a line with a dash, but this dash is to be part of the command rather than a continuation symbol, then use \45 instead or put a comment AFTER the dash. Trailing comments can be used only in command files. All text starting with the first semicolon through the end of line is ignored. If you need to include an actual semicolon in a command, precede with a backslash (\;). If you need to include a question mark in a command file, use \63. A literal question mark will cause a help message to appear on your screen. There may be translation errors in the VT320 emulator for international characters entered at the keyboard or received from the host when the terminal character set is LATIN1 (none are currently known). If you encounter a mistranslated character, or you want to change one of Kermit's proper translations, use the SET KEY and SET TRANSLATE INPUT commands. For example: SET KEY \199 \195 ; Make key scan code 199 send code 195 SET TRANSL INP \195 \199 ; Translate arriving 195 code to 199 REMOTE TYPE and other REMOTE commands may result in an error "Unable to open CON". This can result from insufficient FILES= in CONFIG.SYS or systems with all file handles used by, say, a network shell. FILES= should be at least 20. Other errors may be introduced by your DOS Environment line COMSPEC=, which Kermit uses to find COMMAND.COM in order to execute PUSH, RUN, and other commands. This line is set by the SHELL= line in your CONFIG.SYS file. If you have a COMSPEC= line, make sure it designates the location and name of your DOS command processor. Furthermore, if you have a SHELL= line in your AUTOEXEC.BAT, it will result in a SHELL= line in your DOS environment, and this will take precedence over your COMSPEC= line, so if you use one of these, make sure it is correct too. To examine your DOS environment for COMSPEC= and SHELL= lines, type the DOS command SET by itself with no arguments. Printer support... Transparent printing is started when the host sends the sequence ESC [ 4 i, and stops when the host sends ESC [ 5 i. Transparent printing passes all characters, including escape sequences, that arrive at the port directly to the printer without translation (but strips off the parity bit if Kermit's parity is not NONE). Character translation for printing -- whether done by transparent print, PrintScreen key, logging to PRN, etc -- if needed, must be done by the DOS printer driver or other utility outside of Kermit. When using Kermit through a terminal server (particularly those that execute the TCP/IP Telnet protocol), it is often necessary to SET PARITY EVEN in order to transfer files. It is also often impossible to use very long packets. Try SET RECEIVE PACKET-LENGTH 80, working up or down to the longest length that works. MS-DOS Kermit must be assembled with MASM (Microsoft Assembler) 5.0 or later (and linked with the accompanying LINK), because the symbol tables are too big for earlier MASM versions. (In fact, all modules but MSZIBM.ASM can also be assembled by MASM 4.0.) Reportedly, the program can also be built using Borland TASM (although several harmless warning messages appear) and TLINK, as well as Xenix MASM/DOSLD, and Intel ASM86, but MS-DOS Kermit is designed to be built by Microsoft MASM and LINK. On early (original motherboard & BIOS) PCs, and on systems that mimic them (e.g. early Compaqs), the cursor may assume a strange shape upon return from CONNECT mode. This is caused by a bug in the early BIOS, which stored cursor attributes incorrectly. The PC Tech Journal article discussing the problem is "The Dashed Cursor", by Paul Pierce, PC Tech J., Dec. 1985, page 47. He suggests the following fix: ; ; Program FIXCURS.ASM by Paul Pierce, PC Tech Journal, Dec 1985, page 47. ; code segment public 'code' assume cs:code, ds:code, es:nothing ; ; This program is set up to be made into a COM file ; org 100H ; ; First check for the monochrome adapter. ; start: int 11H ; set ax = equipment flag and al,30H ; mask off all but video bits cmp al,30H ; test for monochrome adapter jne exit ; jump if not monochrome ; ; Now check for incorrect cursor mode returned from the Bios ; mov ah,3 ; call bios to get cursor type int 10H ; cmp cx,0607H ; check for invalid (color) type jne exit ; jump if not a bad value ; ; At this point we know that the monochrome adapter is in use and that ; the bios cursor mode is incorrect. ; Call the bios to set the cursor type correctly. ; mov cx,080cH ; use correct cursor type mov ah,1 ; call bios to set cursor type int 10H exit: mov ah,0 ; exit back to DOS int 21H code ends end start GENERAL WORDS ON DOS VERSUS ANY COMMUNICATIONS PROGRAM Shift-Printscreen can cause the PC to hang if there is no attached printer. This is a BIOS feature, Kermit never receives the command. It occurs most frequently with a printer interface that has nothing plugged into it. If this happens during terminal emulation, try pressing Alt-= several times to reset the terminal. When used in remote mode, e.g. as a server, a REMOTE HOST command can invoke the DOS critical error handler, which issues its familiar "Abort, Ignore, Retry?" message on its real screen, and is waiting for a response from its own real keyboard, and so the server will no longer respond. Kermit attempts to catch many of these errors before DOS learns learns about them, but some cannot be avoided (like disk i/o errors). Interaction between MS-DOS Kermit and various terminate-and-stay-resident (TSR) programs is necessarily unpredictable, depending upon how "well behaved" they are. Certain console, mouse, or graphics drivers might interfere with file transfer, etc. Caution should be used when invoking certain TSR programs while PUSHed from Kermit (e.g. using the PRINT command for the first time), as not all of these programs observe proper etiquette for allocating and freeing memory, and more importantly the TSRs will be loaded above Kermit into the middle of memory where they may prevent large programs from loading later. As a concrete example of the above, certain mouse drivers may prevent Kermit from transferring files, and possibly also from recovering from timeouts during script execution, or even from XOFF deadlocks during terminal emulation. This is because Kermit and the mouse driver are competing for the same interrupt, and the mouse driver might not be playing by the rules. Possible workarounds include: (1) remove the mouse driver from your CONFIG.SYS file; (2) if your mouse driver can be turned off and on (e.g. if you have MOUSE OFF and MOUSE ON commands), turn the mouse off during Kermit execution; (3) give the MS-DOS Kermit command SET TIMER OFF. If TSR programs are interfering with Kermit (by taking over the timer or serial port interrupts), you should remove them all from your AUTOEXEC.BAT or CONFIG.SYS files, and then put them back one by one until you have identified the one that's causing the problem. Don't run this one while running Kermit. MS-DOS Kermit may be run as an external protocol by other programs, such as BBS systems. Kermit restores the interrupt vectors properly, and leaves communication port interrupts turned off, as it should. It is the responsibility of the invoking program to turn them back on if necessary. Some PCs have more than two serial ports, but until recently there has been no standard about addresses for COM3 and COM4. PC DOS 3.30 does not assign them either because it is really a problem of the system ROM Bios boot code run when the power is turned on. However, Kermit will use COM3 and/or COM4 if the base address of a port is placed in low memory words 40:4H (COM3) or 40:6H (COM4); the tests described above are then carried out. One restriction is that the Interrupt ReQuest number (IRQ in the serial port board manual) must be either IRQ4 or IRQ3. Kermit attempts to locate which line is correct with a short test. If the test is not successful it uses the IRQ4 for COM3 (and for COM1) and IRQ3 for COM4 (and for COM2) on the PC/AT, and on the PS/2 it uses IRQ3 for COM2, COM3, and COM4. Check your communication board and its manual. The DOS utility DEBUG can be used to create a short program to insert the board's addresses into the segment 40H memory locations; a sample program is given below. IBM PC/XT/AT and PS/2 Serial Port Numbers: Serial Port Address IRQ Line Conventions COM1 03F8H 4 IBM standard COM2 02F8H 3 IBM standard COM3 ? 4 (3 for PS/2) Board COM4 ? 3 Board The addresses shown as query marks are to be found in the board's reference manual; values such as 2E8H and 2E0H would be common. However, there is no standard for anything to do with COM3 and COM4 on non-PS/2's. Assuming that you have selected an address in harmony with the rest of the system, set the board's switches or jumpers, and use DEBUG to insert the address(es) in segment 40H memory. The example below creates a small program named SETCOM3.COM to put address 02E8H into the memory word 40:04H for COM3 and writes the program to drive A. Substitute the desired drive letter for "a:" in the second line below. The dash (-) is DEBUG's command prompt, and the xxxx:nnnn lines are addresses for which DEBUG prompts you to type an instruction, such as "mov ax, 40". A> DEBUG don't type these comments -n a:setcom3.com sets name of output file -a assemble command xxxx:0100 mov ax,40 value 40h xxxx:0103 mov es,ax put it into register es xxxx:0105 mov ah,02 the 02 part of 02E8H xxxx:0107 mov al,e8 the E8 part of same xxxx:0109 es: xxxx:010A mov [4],ax store in 40:4 for com3 ([6] for com4) xxxx:010D int 20 return to DOS xxxx:010F blank line to end assemble mode -r cx show contents of register cx CX 0000 : 0f set register cx to write 0fh bytes -w write material to the disk file -q quit debug A> DEBUG setcom3.com -u unassemble to see if all is well -q quit debug Note, for COM4, use [6] above rather than [4], and of course employ your board's port address in place of 02E8H (check the manual). Finally, try it: A> setcom3 run the program A> DEBUG now see what's down there -d 40:00 display bytes in seg 40H ( Shows many bytes. See yours? Good. ) -q A> A small side effect noted in practice is the first time the extra port is used there may be garbage from it. Just return to the Kermit prompt and try again, if necessary SET PORT to the other COM lines momentarily, all should be well the second time. KNOWN BUGS IN MS-DOS KERMIT VERSION 3.0 SET EOF CTRL-Z, when used to upload text files which actually contain Ctrl-Zs, might result in gaps or truncation in the vicinity of the Ctrl-Z. This is an artifact of DOS file i/o. The graphics display on the PS/2 Model 30, whose graphics adapter is neither a real EGA nor a real VGA, is elongated vertically so that certain normal Tektronix graphics images might not fit on the screen. Reportedly, MS-DOS Kermit 3.0 sometimes loses certain terminal settings, such as WRAP or tab settings. This might be caused by Kermit's new ability to accept VT300 8-bit control sequences when connected to a system that sends parity, and you have given the command SET DISPLAY 8 (which should not normally be done). To restore default tab settings quickly, use the command SET TERM TABS AT 1:8. Some users have reported extended waits if they use a network connection and have said MODE COM1:speed,n,8,1,P. The trailing P means "Printer", telling DOS to do very lengthy retries, and if DOS gets control of the port it may do just that. Suggested alternative is to remove the ",P" above. Recall, SHOW commands that need information about a serial port may activate COMx unless another port has been selected. Reportedly, Kermit does not operate properly on a PS/2 Model 25 under DesqView. Further reports welcome. Reportedly, Kermit receives a file access error when attempting to write files on a PC-NFS file server. Further information is needed. ------------------------------------------------------------------------- ADDITIONS TO THIS FILE AFTER VERSION 3.0 WAS RELEASED ON JANUARY 16, 1990: The non-IBM-compatible versions of MS-DOS Kermit 3.0 are not done yet. Some (DEC Rainbow, Heath/Zenith-100, HP, GRiD) are currently in preparation and will be announced when they are ready. Volunteers are needed for the others (Victor, Sanyo, TI, NEC, etc). In the meantime, the new mss*.* source files are incompatible with the old msu, msg, msx, msy, and msz system-dependent source files for the non-IBM systems. Characters that arrive during terminal emulation that are translated by the SET TRANSLATE INPUT mechanism bypass the current shift-in/shift-out state. This means that SET TRANSLATE INPUT cannot be used successfully with an 8-bit terminal character set in a 7-bit communication environment. The MSKERMIT.INI file on the distribution diskette contains two errors: 1. In ERRSTP definition, "\%\13" should be changed to "\%1\13". 2. In COPY definition, second "if < argc 2" should be "if < argc 3". These errors are fixed in the online copy. When using version 3.0 in terminal mode with a DEC operating system (like VAX/VMS) that knows your terminal type is VT320, you should SET DISPLAY 8 in order for Kermit to properly process 8-bit graphic and control characters which certain applications (such as Word-11 and EVE) will send. RTS/CTS half-duplex hardware handshaking does not work in all circumstances. Reportedly, Wyse big screens have problems in Tek mode. Version 3.00 hangs when run on AT&T 6300 PCs running MS-DOS (not PC-DOS) 3.10. This can be fixed using a DEBUG patch listed in MSVIBM.DBG. Reportedly the "LEDs" in the mode line don't work during VT320 emulation, but they continue to work in VT102 emulation. Orchid Designer Professional VGA board doesn't work in 132-column mode. This is because this board has the same signature (video mode) as the earlier, incompatible model (Orchid Designer), and Kermit can't tell the difference between the two. Although Kermit does not handle REGIS graphics, there is reportedly at least one REGIS-to-sixel converter on the market: RETOS, a DEC product for VAX/VMS. So that key translation and macros can work on both IBM and non-IBM compatible PCs, Kermit uses the system BIOS to obtain key scan codes. But the IBM BIOS does not produce scan codes for certain keys, notably Num Lock. Unfortunately, Num Lock happens to be exactly where you would want to put the DEC PF1 (Gold) key for DEC VT keypad-oriented applications. SET LO is no longer a sufficient abbreviation for SET LOCAL-ECHO. Use SET LOC. Reportedly, scrolling does not work correctly on the Zenith 386SX PC (also said to be true of earlier versions of Kermit). Most likely a problem with this machine's video BIOS. Defining a session log using a macro does not work properly: if you DEFINE XXX LOG SESSION X.LOG, then XXX results in a transaction log rather than a session log, and to add to the confusion, SHOW LOG reports that a packet log named X.LOG is in use. The same bug happens with LOG PACKETS. A real VT300 series terminal prints received Ctrl-Z characters as big reversed question marks, but Kermit does not print anything for this character. This can cause alignment problems when editing files using TPU on VAX/VMS, etc. CD command displays the new directory. Version 2.32/A didn't do this. This behavior can be annoying in script or TAKE file execution. Reportedly, the Norwegian/Danish NRC terminal character set mistranslates capital O-slash (the replacement for ASCII \) as small o-slash (ASCII |) under code page 865. If you SET PORT DECNET, the maximum length of a Kermit command is reduced to seventeen characters. Temporary workaround: After giving the command SET PORT DECNET, make sure the next command is 17 characters or less. After that, everything is back to normal. Reportedly on the NESS-286, NESS-88, and Olivetti M24 PCs, it is necessary to type Ctrl-Break after escaping back from terminal mode with Alt-X in order to get the MS-Kermit> prompt. Furthermore, the NESS-88 cannot reconnect after escaping back (this is said to be caused by a BIOS bug). Reportedly, version 3.00 with SET PORT BIOS1 causes Rainbow Software's (Edinburgh) PADPORT TSR program to go into a endless loop, whereas 2.32/A and earlier did not. Reportedly, in order for version 3.0 to work properly under DESQview, it must be given at least 160K, even with only one screen of rollback memory. If insufficient memory is allocated for Kermit under DESQview, garbage will appear at the MS-Kermit> prompt upon escaping back from a terminal connection, and then Kermit hangs. Reportedly, Kermit does not work well with the IBM EBIOS Async communication server. Many characters are lost. Limitation (not bug): SET TERMINAL CHARACTER SET is effective only for text screens, not for graphics screens. This is because the fonts for all the special characters have not been designed yet. SET TERMINAL COLOR is effective only for text screens. The ANSI coloring escape sequences, ESC [ ... m, may be used to control the colors on the graphics screen. The PC hangs upon escaping back from connect mode on a communication port if the DOS command MODE COM1:speed,n,8,1,P has previously been given. Solution: before using Kermit, give a similar MODE command, but without the P. If you find your PC hung in this way, type Ctrl-Break one or more times to get the MS-Kermit> prompt back. End of file KERMIT.BWR.