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Unable to access mapped drive letter with 16bit apps

Posted on 2012-04-12
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Last Modified: 2012-04-19
I have two Win16 apps - Ztree and Foxpro for Windows 2.6 that have happily used mapped network drive letters for the last 15+ years.

Now they both return an error "Path not found" when trying to access the network share as drive letter N: but can access the UNC \\Server\shared without a problem. Using the Cmd dosbox and logging onto the N: drive also works.

I have a new VFoxpro 9 app recently installed and think there may be some old DOS settings altered.

I have done a system restore to when both apps ran fine but the problem persists.
I have looked for file date changes but cannot see anything untowards.

TIA
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Question by:hpyatt
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Expert Comment

by:2G33K4U
ID: 37836702
I do believe 16bit apps had a limitation on name length. Have you tried making a new share with a very short name as a test. Just a thought.

Here is an article that may help explain it some. But I am pretty sure your 16bit applications are not going to work.

The Lifehacker Guide to 64-bit vs. 32-bit Operating Systems

This article also goes into 16bit applications and how they are no longer usable.  The price of technological advancement.

I just noticed you did do a little experimentation.
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Author Comment

by:hpyatt
ID: 37836840
Thanks but all shares and names follow the 8.3 short format. These apps have been working for 15 years and still do today on other machines on the network running 32bit Win7. The problem is local to just one machine.

I can get away with \\server\share but cannot understand why trying to log to N: returns "Path not found" in two apps whose only link is that they are 16bit. It's an OS config issue I am sure. Unfortunately some of the old Foxpro apps still use hard coded drive letters !! and I don't want to have to touch this very old code because I'm sure other issues will arise if I do.

I appreciate that the 16bit apps do not work with 64 bit Win7 but you can use a virtual os box to get round that issue.
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by:2G33K4U
ID: 37836843
Very true. Sorry I could not be of more assistance.
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by:jsrebnik
ID: 37842173
First the obvious - is the hardware the same (server and stations)?

Do you have a copy of the Fox 2.6 development language or does your app have a simulated command box?  If you have either, try issuing the BROWSE command.  If there are no tables open, it will bring you to a dialog box where you should see a drive letter pull-down.  I'm curious if the N: drive is visible there.
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Expert Comment

by:ChiefIT
ID: 37845252
See if your host based firewall has been enabled on the server again (Windows Firewall).

Also, this might be Internet Explorer Enhanced Security.

http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Server/2003_Server/Q_23351830.html
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JT92677 earned 200 total points
ID: 37845348
When you go to the CMD: prompt and type

NET USE

what do you see?  If the N: drive is mapped to a network drive, it should be clear.

if not, you need to map the network drive while in windows (my network places, highlight the resource you want to map, then map it),

If the mapped drive isn't N:, no problem, you can also use SUBST to substitute
N: for the drive that is previously mapped (like a persistent mapping).

So I can MAP the U: drive to a remote computer/directory
Then at the CMD: prompt, I type
NET USE
and it tells me how U: is mapped

I can then use SUBST N: U: and now N: is mapped to the same place.

So bottom line, what shows up when you issue the NET USE command at CMD: prompt?

Is there some limit to the number of drive handles? 16-bit apps use handles, maybe you don't have a spare one to use for the DOS app -- I'm just putting this here so I can check out the settings for handles and lastdriv etc. in the DOS environment.

This takes me back years but at the CMD: prompt, try these ideas
SET
This will return the environment settings, a long list no doubt
Then try
SET FCBS
It may be zero or nothing returned
Try
SET FCBS=10
Then try SET again

Another setting of interest is LASTDRIV
try SET LASTDRIV
if it's not beyond the N: drive try
SET LASTDRIV=Z

There's probably more environment variables that have a bearing on the old 16-bit way of opening filess

In the olden days, before Windows, we used File Control Blocks with all sorts of interesting data fields in the BLOCK, and I'm not sure Windows has any FCBS when you first boot up.

My brother still uses Foxpro and I helped him setup a virtual machine for it, and we had to map a network printer to LPT1: so it could print, etc.  The good 'ol days, eh?

Jeff
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Author Closing Comment

by:hpyatt
ID: 37865512
The trip down memory lane certainly helped - took me back to the days of dBASEII and trying to get a workable application with only 32 fields in a table and 64 memvars !<br /><br />Net Use brought the problem into focus.<br /><br />Some_idiot(tm) had created a share on the server with the same name as the shared folder !<br /><br />The client can map to \\server\drive\folder or \\server\sharename<br /><br />If the client maps to \\server\sharename then the 16bit apps get confused and return Path not found. Mapping to \\server\drive\folder solved the issue.
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Expert Comment

by:JT92677
ID: 37866196
I'm not sure how to reference another Q&A in EE but here's a longer explanation of how I print to LPT1: (see the last answer under JT92677) if printing to a network printer is also needed in your DOS app.

http://rdsrc.us/wXcyoa

Jeff
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