Computer is set up for multiboot with Dos,W98 or W2000 in separate primary partitions. Computer is a new P4 with Intel 845 chipset motherboard. When I write to the com port with Dos6.22, I get write errors and have to retry numerous times to complete the transfer. This operation did not work at all untill I installed a legacy memory manager, Quarterdeck QEMM, ver 8. When I write to the com port using a dos(dos5)window within W2000, the transfer occurs flawlessly. This operation with Dos6.22 works flawlessly in my older pre Pentium computer. Was curious what the problem is and what I can do to solve it. Thanks, Sinch

how do you write to the com port? own program? can you give the code?

Actually I am communicating with an HP Plotter which appears as a modem-like serial port device using a proprietary cable with hardware flow control using the CTS,DSC,DTR,RTS as handshakes. It does not use XON or DTR timing. The batch file is: mode com1:9600,n,8,1,p copy %1.plt com1: and is called plot.bat. I type "plot filename" at the Dos prompt. I get the message: Write fault error writing device Com1 Abort,Retry,Ignore,Fail? The plotter starts to plot and then stops. I press the R key and the plot continues and then stops. I repeat this process until the plot completes. I do not get an overflow and lose data. I just have to babysit the operation. Using the dos window in W2000, I enter the plot command with the file name and the plot continues to the end with no error messages(as in the pre Pentium computer). I suspect a flow control problem with Dos6.22 and the modern 2.5GHZ P4 Computer. I also suspect Dos6.22 is no longer completely compatable with the P4 computer as other legacy dos programs no longer operate properly in their entirety(ie QEMM,Norton Utilities). Interested in opinion of others. Thanks for responding. Sinch

Nope. Problem not in DOS 6.22. I have a cash drawer. When I attach it to a 486-66 using DOS 6.22, I get write fault on the serial port. When I attach it to P-133 using DOS 6.22, it works fine. When I attach it to PIII-700 using XP-Home, it work from the command prompt. When I reboot the PIII machine using a bootable DOS 6.22 diskette (yuk!) I get the write fault again. In all cases, if I start Laplink 5 the drawer opens every time! Now I am very confused. Any ideas or suggestions would be greatly appreciated!