Hayes Microcomputer Products, Inc. (part of Zoom Telephonics), developed two versions of its AutoSync product to support certain Hayes modems (Ultra and OPTIMA series).  The AutoSync1 version has a maximum speed of 9,600 bps, and AutoSync2 can support synchronous speeds up to 33,600 bps.  CTI's 3780 BSC software automatically detects whether the modem supports the high or low speed version.  The appropriate Hayes modem will return a code that indicates whether it supports the higher speed (AutoSync2) version, or the lower speed (AutoSync1) version.  

Autosync2 is buffered, where AutoSync1 is not.  

AutoSync1 is implemented in FastSync as UNBUFFERED.  That means that once we start a block of data, we have to keep sending it to the modem until we reach the end of the block of data.  If the software stops sending, the modem inserts “time fill” characters into the data stream.  Remember that Bisync requires that the transmitter continuously send data so the receiver can synchronize on the data stream (as opposed to synchrnonzing on a start bit). When the transmitting modem is in AutoSync1, the modem sends the data as it is received from the computer.  If the computer stops sending data, the modem sends PAD characters. When the TRANSMITTING modem is in AutoSync2 the data is sent out as buffered data.  This means that the modem stores the data block until the computer (Fastsync 3780 software) tells the modem that the block is complete.  Then the modem sends the data. This prevents pads, but it means a longer delay between blocks. Note: Do not use AutoSync1 on PCs running with Win2000 or NT operating systems.

AutoSync2 is implemented as BUFFERED.  That means that we send the entire block to the modem and then indicate to the modem that we are finished and the modem can begin sending the data.  In other words, the modem doesn’t send any data until it has the complete block.  This makes the process immune to FastSync being suspended by the OS.  When using AutoSync2, the modem waits until it has a complete block of data before beginning transmission.

Since about 90% of all mainframes use V.32 9,600 bps links and most of their mainframe front-end modems can't train with clients trying to call in using V.34+ 33,600 bps modems, you may want to force a 9,600 baud connection.  If you want to for the modem to 9,600 baud, use the Hayes AT command "ATS37=9" at the beginning of your command file.  See: Tech Tips/Command Files.

CTI's software can force the 3780 program to use the low-speed version of AutoSync by using the DOS command line argument, .AUTOSYNC1.   This argument can be included on the normal DOS command line each time FastSync is run, or it can be included by running the program CMDLINE.EXE if you want the argument to be included every time FastSync is run.

A user may chose to include the .AUTOSYNC1 option through CMDLINE.EXE, run CMDLINE.EXE by keying in "CMDLINE" at a DOS prompt in the directory containing the FastSync software.  The user selects the down arrow key to choose "User Entered Option" from the menu and press the ENTER key.

The user can end the program CMDLINE.EXE by pressing the ESC key. To remove the .AUTOSYNC1 option, run CMDLINE again, press the right arrow key and then use the up and down arrow keys to highlight the option you want to remove.  Remove the option by pressing <ENTER> with that option highlighted.

Win95/98/ME/NT Drivers  V90 U-Grades(1)

Win2000 Drivers  XP Drivers

(1) Notice to users to CTI's FastSync 3780 BSC Software.  No NOT up-grade your Optima 336 modems to 56k (V90).  This would disable your 3780 software.