Ask Dr. Bob Your NT Questions - 01 Apr 1996

Q: NetWare has a formula to calculate the memory it needs to run properly. Does Windows NT 3.51 have a similar formula?

Although the following formula is largely unknown, it can give you a rough estimate of memory requirements; however, the formula doesn't take databases such as SQL into account.

System memory (minimum required 16 MB) = A

User data:

Average size of data files open
per user = B
Number of users = C
Multiply B by C = D


Average size of executables being run off the server = E

Number of applications being run off the server = F

Multiply E by F = G

Total system memory recommended for this configuration = A + D + G

Q: When I try to copy files from my NT Server to my satellite NT Workstations on a Token Ring network, I get the error message, "File manager cannot copy X. The session was canceled." The copying begins just fine with a few small 350-byte files, but when it reaches the first large file (64KB), File Manager chokes on it.

This is a case for editing the Registry (use REGEDT32.EXE).

1. Traverse the Registry tree until you come to the HKEY\LocalMachine\System\CurrentControlSet\Services\NETFLX1\Parameters\MaxFrameSize.

2. Double-click on the parameter MaxFrameSize:RegDword and set the value to 0x800. This entry sets the maximum frame size to 2KB.

Q: After changing passwords and adding autologon, I lost the ability to manage my system (change display resolution, edit the Registry, use Disk Administrator) with this account. How can I fix this problem?

Autologon automatically uses a given user ID at boot time. If that ID becomes corrupted, you can lose some of the capabilities associated with that ID. To fix this problem, at boot time, hold down the shift key to get a prompt for a password. Then you can sign on as a different user and repair the corrupted user ID.

Q: In NT 3.5, when a 16550AFN UART chip set was seen, we used to get a message that a FIFO was enabled. We no longer get this message. How can we get it back?

Do the following, which is laid out in screen 1:

1. Run the Registry Editor \system32\REGEDT32.EXE

2. Select the key \HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Serial

Make certain the following values are present. If they aren't, add them.

ForceFifoEnable REG_DWORD 1


PermitShare REG_DWORD 1


(for maximum read throughput) TxFIFO REG_DWORD 10

(for maximum write throughput)

Exit the Registry, and reboot the system. The system event log will now report, "While validating that COM1 was really a serial port, a FIFO was detected. The FIFO will be used."

Q: My password will expire in two weeks, and I tried to put in a new one. I hit return to get past the logon window, and somehow I ended up with no password. How can I easily get back to a real password?

After you log on, press Ctrl+Alt+Del to get the security window. There, you'll see the Change Password button.

Q: I updated to Service Pack 2 and am now getting errors and crashes I never had before. How do I uninstall it?

I hope you had the foresight to do a tape backup before adding Service Pack 2. If so, you can restore your system and reboot.

If you don't have a current tape backup, you can boot from the install diskettes and run Repair/Check System Files to return the system to a working state before you add any Service Pack. Be prepared to check all your applications.

Q: We have recently been getting the infamous Stop error message, IRQL_NOT_LESS_OR_EQUAL Address. What does it mean, and how can I find out the cause?

You get this message when a kernel mode process (NTOSKERNL.EXE) tries to access a memory address it doesn't have permission to access. Unfortunately, many things can cause this infamous message. Try the following ways to deal with frequent causes of the message.

1. During setup, select a standard PC configuration instead of letting setup autodetect it.

2. Disable both the CPU cache and the external cache.

3. Simplify the machine as much as possible: Remove all cards (especially network interface cards) not necessary to run NT. Also, you can disable shadow RAM/shadow ROM, L2 cache options, virus programs in CMOS, and the daylight-saving time options in CMOS.

If these steps don't work, you can try a low-level format of the drive. Then, you can run setup again. If nothing seems to work, you have to call the vendor who sold you the machine.

Please see "What's a Service Pack?" and "The Registry Subkey Already Exists".

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