DFXX IS BROKEN VERSION OF DFX DOS FILE EXCHANGE [1.1] ======================= PROGRAM BY BLACKSMITH (C) 1982 BY ARROW MICRO SOFTWARE INTRODUCTION ------------ DOS FILE EXCHANGE (DFX) is a program for transferring DOS 3.3 files between APPLE II computers that are equipped with the HAYES MICROMODEM II*. DFX supports an APPLE to APPLE terminal "CHAT" mode that allows both ends to type messages to each other at the same time that files are being transferred. HARDWARE REQUIRED ----------------- APPLE II 48K APPLESOFT in ROM or LANGUAGE CARD HAYES MICROMODEM II in slot 2 DISK II in slot 6 SOFTWARE REQUIRED ----------------- DFX PRIMARY DISK DOS 3.3 SYSTEM MASTER INDEX ----- HOW TO RUN DFX .....................2 ERROR HANDLING .....................4 LIMITATIONS ........................5 INTERNALS ..........................5 MAKING COPIES OF DFX ...............7 * Indicates trademark of Hayes Microcomputer Products. Inc. APPLE is a registered trademark of APPLE COMPUTER INC. HOW TO RUN DFX -------------- LOADING THE PROGRAM Run the program called DFX on the LOCAL and REMOTE APPLE II computers. The program makes a quick check to see if the phone line has a clean data carrier present, in which case DFX will accept the current call and present the M-$-& menu. If no carrier is detected, DFX will hangup the line and present the following C-& menu: C .... CALL ORIGINATION & .... BOOT DRIVE 1 WAITING FOR CALL The "WAITING FOR CALL" message means that the system will auto-answer the telephone if a RING is detected. PLACING THE CALL Type "C" to originate call. Then type the telephone number of the other APPLE as requested and let DFX dial the number via the modem. If an answer is received within 30 seconds, the call will be connected and the following M-$-& menu presented. M .... MASTER MODE $ .... HANGUP LINE & .... BOOT DRIVE 1 CHAT MODE A flashing cursor near the bottom left of the screen indicates that you are in CHAT mode connection with the other APPLE. Likewise, the REMOTE APPLE will be in in CHAT mode connection with you. This means that you may type messages to each other within a three line scroll area just above the STATUS display line at the bottom of the screen. All the non-control characters may be typed, and in addition, the control-G will ring the bell. The LEFT ARROW key will backup the cursor as far as the left margin. FUNCTION MODE To select any of the MENU items, you must toggle your keyboard from CHAT to FUNCTION mode by using the FORWARD ARROW key. THE STATUS DISPLAY As you play with the CHAT-FUNCTION toggle, you will notice that at the bottom right of the screen in the STATUS display there is a "C" or "F" indicating the current state of the LOCAL APPLE. If the REMOTE starts to toggle his CHAT-FUNCTION state, you will see his current state at the left of the STATUS display. HANGING UP THE LINE Selecting "$" will hangup the telephone line and within about 15 seconds, both APPLES will reset to the original C-& menu and the WAITING FOR CALL state. RETURNING TO DOS Selecting "&" will leave the telephone line connected and cause the system to BOOT from DRIVE 1. TRANSFERRING FILES To transfer files, one of you must take control of the total system. This means that one of you elects to become the "MASTER" and the other end becomes the "SLAVE". To become the MASTER, type "M" from the FUNCTION mode and if you succeed in becoming MASTER the REMOTE menu will be replaced by the message:- [CONTROLLED BY REMOTE] You will be presented with the S-R-E menu:- S .... SEND LOCAL FILES R .... RECEIVE REMOTE FILES E .... EXIT MASTER MODE You can toggle between CHAT and FUNCTION mode at any time, but when ready to select from the menu, you must be in FUNCTION mode. Selecting the "E" menu item will relinquish MASTER control and return both APPLES to the M-$-& menu. SELECTING FILES FOR TRANSFER Insert into DRIVE 1 any disk that contains files to be sent or has space for files to be received and select "S" or "R" from the menu. The APPLE that holds the files to be sent will read the CATALOG from its disk and send a copy to the other APPLE. When both ends have copies of the CATALOG displayed, the MASTER end can select the files to be transferred. This is done by moving the selection cursor up and down the screen with the < and > (or , and .) keys while in FUNCTION mode. The MASTER end toggles the file selection with the SPACE bar and both ends can see which files have been selected. When ready to start the file transfer, type CONTROL-C. While your disk is actually being accessed, you will be barred from using the keyboard, but at all other times, including file transmission, you may select CHAT mode and converse with the other end. WATCHING THE DATA GO BY There are three display screens supported by DFX. They are called the MENU, UTILITY and the GRAPHIC screens. You may switch from the current MENU screen to either the UTILITY or GRAPHIC screen at any time. The ESC key toggles your APPLE between the three screens and the STATUS line shows a U, G or M so that you know where you are. You can even see which screen the REMOTE is currently selecting by looking at the left side of the STATUS line. THE UTILITY SCREEN This shows the Receive and Transmit data streams and an extension of the CHAT scroll area. In FUNCTION mode, the < and > (or , and .) keys move the small arrow under the data stream left and right. The hexadecimal values of the two indicated data stream characters are displayed at the right. A count of the total characters Received and Transmitted is displayed on the left. THE GRAPHIC SCREEN The GRAPHIC screen shows 32 blocks of any file in transit. If it is a HIRES picture file, the sender will see the picture as loaded from disk, while the receiver will see it slowly appear. There are no valid FUNCTION mode keys while using the GRAPHIC screen. ERROR HANDLING -------------- FAILURE TO GAIN MASTER CONTROL If you both managed to type "M" almost simultaneously while attempting to become MASTER, then you will both get a NOT ACCEPTED BY REMOTE message. If you have placed a call to another computer that is not running DFX, then you will get the NOT ACCEPTED BY REMOTE message after typing "M". DISK ERRORS If disk errors occur, both ends will be informed by a message at the top of the MENU screen. The MASTER end will be asked to type a SPACE in FUNCTION mode to terminate the file transfer and the system will reset to the S-R-E menu. TRANSMISSION ERRORS During file transmission, each block of 256 bytes has a checksum appended so if line errors occur, the checksum will not match the receivers calculated checksum. A RESEND PREVIOUS BLOCK signal (NAK) will be returned by the receiver and the block will be resent. However, no error correction is applied to the CHAT sequences. INTERUPTION OF FILE TRANSFER Once a selection of files has been made and transmission started, either end may ABORT the process without dropping the telephone line. Select the UTILITY screen, FUNCTION mode and type SHIFT-CONTROL-P. This will signal the REMOTE APPLE to close any open files and return to the M-$-& menu. If successful, the LOCAL APPLE will then do the same. If either APPLE was in the middle of a disk access at the time, you may have to repeat the sequence again. LIMITATIONS ----------- * All disk functions refer to DRIVE 1. * The HAYES MICROMODEM II must be in slot 2. * All files must be in standard DOS 3.3 format. (APPLESOFT, INTEGER, BINARY or TEXT). * If the sender's CATALOG has more than 38 files, only the first 38 will be displayed for possible transfer. * If the sender's CATALOG has more than 19 files, the display will show all file names truncated after the 12th character. However, the file names up to the 30th character are still used internally. * At least one end must be running an original DFX PRIMARY DISK as provided by ARROW MICRO SOFTWARE. The other end may be a SECONDARY copy produced by any suitable file copy program, bit copier, or by the DFX PULL-THROUGH (DPT) utility. If you attempt to run SECONDARY copies of DFX in both APPLES, you will be permitted to place the call, CHAT and select files; but you will not be permitted to transfer any files. The slowly flashing "*" at the centre of the STATUS line will break into a fast flash if both ends are running SECONDARY copies of DFX. Also, the message:- [NO PRIMARY DFX DISK] will be displayed when you enable the M-$-& or S-R-E menu. If you attempt to transfer files between two SECONDARY copies of DFX, you will be forced to press RESET which will drop the line and reboot. INTERNALS --------- DFX is a small APPLESOFT program that loads and executes four binary program segments. MODEMSUB.OBJ is the operating system that supports the three screens, CHAT-FUNCTION, STATUS display and modem. DFXAPPLN.OBJ is the File Transfer Application routine. DFXAPPLNMSG.OBJ contains all the messages for DFXAPPLN.OBJ. DFXGSODS.OBJ makes various modifications to DOS 3.3 and initializes all variables. It then evaporates. DFXDOCUMENTATION is a formatted text file of this documentation. DOC is a rather slow and simple minded APPLESOFT program that prints the DOCUMENTATION file to a printer in slot 1. DPT is an APPLESOFT program that will send a copy of the DFX files to a REMOTE. GETTING OUT OF DFX When exiting from DFX, it is necessary to reboot the system with a more normal DOS 3.3. The "&" character has been chosen as the menu selection character because it requires a SHIFT and "&" key to reach it. This helps avoid accidental reboots. Likewise, the "$" key is used in the M-$-& menu to hangup the line. Even then, you must be in FUNCTION mode. CHAT AND FILE TRANSMISSION The CHAT mode can coexist with the file transfer because, as you will see from the data stream on the UTILITY screen, all CHAT characters are preceded by a special ESCAPE character ($FE). When a $FE is found in the file data block, two of the special ESCAPE characters are sent and treated as only one at the other end. WHEN THE DISK IS ACTIVE The disk read and write routines prevent the APPLE processor from servicing the modem for short periods. In order to prevent any characters from being lost, the REMOTE APPLE is sent a special signal to prevent it from sending until given a second GO AHEAD message after the disk operation is finished. During this "lockout" period, the REMOTE APPLE will buffer any CHAT characters and delay their transmission until given the GO AHAEAD signal. DFX WITHOUT A TELEPHONE LINE There is a hidden menu character in the C-& menu that will be of interest to those users that have access to two APPLES in the same room. You may connect the two modems directly, back-to-back, without actually involving the telephone lines. To place a call, type "C" and at least one digit followed by a . Since there is no ring signal available to the answering machine, just type "P" (for pickup) and it will cycle through its answering program. MAKING COPIES OF DFX -------------------- SECONDARY COPIES All the files on the DFX PRIMARY DISK may be copied to another disk that has been initialized by the INIT program on the DOS 3.3 SYSTEM MASTER. The result is a Secondary copy of DFX. The SECONDARY copy will inherit the same serial number as the original DFX disk but the letter "S" will be seen to be appended. (The serial number is displayed at the bottom left of the screen before any call has been placed.) You may make and distribute as many SECONDARY copies of DFX as you please, but remember that to be able to transmit files, one of the two APPLES must be loaded from an original PRIMARY copy of DFX which is obtainable from ARROW MICRO SOFTWARE. DFX PULL-THROUGH There is a utility program called DFX PULL-THROUGH (DPT) on the DFX PRIMARY DISK which will let you send a SECONDARY copy of DFX to another APPLE by using the neat facilities of the HAYES MICROMODEM II ROM. Here is what you do:- Call the user at the other end and tell him to BOOT the DOS 3.3 SYSTEM MASTER DISK. He should then remove the disk and insert a write enabled blank disk into drive 1. Warn him that this disk will soon be initialized and all existing files erased. THE PULL-THROUGH CALL Now you must get your APPLES connected together in the standard way as described in the HAYES MICROMODEM II manual. That is:- Let him type IN#2 so that you may place the call. Now you type IN#2 , control-A, control-H, control-A, control-Q. Enter the telephone number of the other APPLE and . When the connection has been established, type control-A, control-X to exit from TERMINAL MODE and then RUN DPT. Sit back and watch for about 8 3/4 minutes. WHEN DPT FINISHES He should now have a SECONDARY copy of the DFX files on his disk and DFX should be up and running on both APPLES. If all goes well, your DFX will be running a few seconds ahead of his and you will see his CHAT status "C" appear when his DFX starts up. It is now safe to chat to him. If you start chatting too soon, his system may hangup the line because he sees strange bits on the line while he is testing the connection. SENDING THE REST OF THE DFX FILES To complete the SECONDARY DFX file complement, you should now use DFX to send him the files called:- DOC, DFXDOCUMENTATION, ORDERING, HELLO and DFX. (HELLO and DFX are required to replace the temporary files sent by DPT.) COPYRIGHT --------- This software product (DFX) is copyrighted and all rights are reserved by ARROW MICRO SOFTWARE. The distribution and sale of this product are intended for the use of the original purchaser only. However, lawful users of this program are hereby licensed to execute the DPT program to transmit a SECONDARY COPY of any of the DFX files to other users for the purpose of usefully executing the DFX program between APPLE II computers. Note: In any DFX to DFX communication, at least one end must run a PRIMARY COPY of DFX to work correctly. No warranty, either expressed or implied, is made with respect to any part of this software. The programs are sold "AS IS". In no event shall AMS be liable for any direct or indirect, incidental or consequential damages resulting from any defect in the licensed program.