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Does Windows 2000 handle serial ports differently than previous OS?

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tmcelroy

Programmer
Mar 23, 2001
5
US
I have a Dell Inspiron laptop Windows 2000 PC. I have a timeclock that communicates with my PC using a RS-232/RS-485 converter attached to my nine pin serial port. While connected to the serial port, the timeclock badge swipe mechanism does not work. The timeclock badge swipe works when connected to Windows 95/98 computers. I have serveral different Windows 2000 PC's and none of them work with the timeclock. The timeclock badge swipe stops working during the loading of Windows 2000. It works fine if the PC is booted up in command mode. I have checked the COM port settings and they are the same as on the Windows 98 PC's that work. Does Windows 2000 do something different to serial ports that Windows 95/98 did not?
 
Windows 2000 does not share the lower 64KB of memory with DOS - and therefore things like COM ports can only be accessed via the VxD. If the program is trying to read / write to the hardware COM address directly Win2000 won't allow it - and there is your problem.

Win 3.1 / 3.11 / 95 / 98 / Me have DOS as a substructure to the 32 bit OS and therefore are much more legacy compatible. All those OS's share with all programs the lower 64KB of memory - this is where DOS loads many IO devices and by sharing them with everything compatability is almost guaranteed. But if one corrupts that 64KB then all programs and the OS crash.

Win NT / 2000 / XP have dropped the DOS structure stubs and anything that expects some of those structures to be there won't run. By not sharing the lower 64KB the system is much more stable - but not very backwards compatible.

Win2000 runs a Command Shell - an emulation of DOS. It is not true DOS with the exact same operational parameters. You will have to run one of the older OS's if you need that compatability. Your mileage may vary...
 
Is there anything I can do to make this work? I have since found some windows 2000 and XP computers that do work with the timeclock, but no discernible pattern or reason.
Thanks
 
Check the hardware addresses set for the COM ports. The standard is:

0x03f8 COM1
0x02f8 COM2
0x03e8 COM3
0x02e8 COM4

most DOS programs have those addresses hard-coded into the software rather than access 'COM1', etc. If your hardware doesn't match those settings chnage the BIOS configuration until they do.

Upon searching it seems that many DOS products are not compatible with 2000 running a NTFS file system, and those that access the COM ports may have problems when Windows 2000 is using a mouse hooked up to COM1 instead of running a PS/2 mouse.

Also, if there is another DOS box or Windows 3.1 program open (and it was there first) and it did not open access to the COM ports all subsequent DOS / Win 3.1 programs will not have COM port access at all as they share the same kernel service.

So there are many things at work, and Microsoft doesn't guarantee DOS compatibility at all.

WE will keep trying, though! :) Your mileage may vary...
 
I put a new hard drive in my Dell Laptop and chose FAT32 rather than NTFS for the file system. Now the timeclock works correctly on the serial port. It seems to be newer computers with Windows 2000 and NTFS have this particular problem. Is there any configuration with NTFS that can be done to correct this, or am I just out of luck?
Thanks for your responses.
 
Hmmm...try a few things.

Use the FORCEDOS command (see FORCEDOS /? for info). Use a full DOS emulator like Apcompat.

The problem seems to be the NTFS kernel, the system timers and the security services that NTFS requires. I am not quite sure of a complete fix - no one else, including Microsoft, mentions one. Microsoft simply states to use FAT if you need to guarantee inter-operability with other OS's - it is fully aware of the NTFS issues. They even go so far as to recommend dual boot and to keep a second version of NT / 2000 / XP installed on a very small partition to access the NTFS volume in case of main OS corruption. All this sounds like a good reason to stay away from NTFS.

Microsoft recommends that if you need data security run FAT volumes and make small partitions for individual functions; i.e. OS, programs, data, etc. Sounds like Microsoft got so much flack from NTFS installs they stopped recommending it - but just won't come out and say it. Your mileage may vary...
 
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