Old DOS program and XP

  • Thread starter Thread starter Donald Canton
  • Start date Start date
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Donald Canton

Hi,

I have a very old DOS program, COMPUTE.COM, that takes a string of
numbers and operators from the command line and computes the
arithmetic result. The program also saves the answer within itself so
the next time it's called the previous answer can be used as part of
the current computation. When I execute this program from my XP Home
(ntfs) CMD prompt, it works fine the first time only, but after that I
get the following error message:

Could not save answer in Compute.com
Compute.com must be in current directory
or in DOS PATH= directory.

Since I'm executing it from the current directory, the program
shouldn't need a search path. It still computes the answer, it just
doesn't store it anymore. Any ideas will be much appreciated as I
find this little program very useful at times.

As an afterthought, is it safe to be executing this program as I'm
sure it uses the old DOS interrupts to write to a FAT16 file system?

Donald Canton
 
Donald Canton said:
I have a very old DOS program, COMPUTE.COM, that takes a string of
numbers and operators from the command line and computes the
arithmetic result. The program also saves the answer within itself so
the next time it's called the previous answer can be used as part of
the current computation. When I execute this program from my XP Home
(ntfs) CMD prompt, it works fine the first time only, but after that I
get the following error message:

Could not save answer in Compute.com
Compute.com must be in current directory
or in DOS PATH= directory.

Since I'm executing it from the current directory, the program
shouldn't need a search path. It still computes the answer, it just
doesn't store it anymore. Any ideas will be much appreciated as I
find this little program very useful at times.

As an afterthought, is it safe to be executing this program as I'm
sure it uses the old DOS interrupts to write to a FAT16 file system?
Click to expand...

I also run WinXP Home with NTFS, and compute.com works fine for me. I
suspect your read-only attribute is on (which happens if the program has
been copied from a CD).
 
In (e-mail address removed)
XP doesn't use Fat16. Only Fat32 and NTFS.
Click to expand...


Not at all true. XP supports all combinations of NTFS, FAT32,
FAT16, and FAT12.


I don't
think XP really supports DOS.
Click to expand...


Correct. It only emulates it. Any program that tries to do its
own file I/O will not run under XP.
 
Gordon Everstine said:
I also run WinXP Home with NTFS, and compute.com works fine for me. I
suspect your read-only attribute is on (which happens if the program has
been copied from a CD).
Click to expand...

Read-only attribute is cleared.
 
Donald said:
I have a very old DOS program, COMPUTE.COM, that takes a string of
numbers and operators from the command line and computes the
arithmetic result. The program also saves the answer within itself so
the next time it's called the previous answer can be used as part of
the current computation. When I execute this program from my XP Home
(ntfs) CMD prompt, it works fine the first time only, but after that I
get the following error message:

Could not save answer in Compute.com
Compute.com must be in current directory
or in DOS PATH= directory.
Click to expand...

I think the trouble will be that the program is trying to save results
in its own program file. And this is open by the system which can't
then open it for update. I think I would take a Hex editor, look for
that COMPUTECOM in the file itself, and change a letter - or even change
the program's extension to .exe, when it may still run, and supply a
separate file for the data to be stashed in
 
Alex Nichol said:
I think the trouble will be that the program is trying to save results
in its own program file. And this is open by the system which can't
then open it for update. I think I would take a Hex editor, look for
that COMPUTECOM in the file itself, and change a letter - or even change
the program's extension to .exe, when it may still run, and supply a
separate file for the data to be stashed in.
Click to expand...

Thanks for the advice. Suppose I use debug to change the filename,
what are the chances of damaging my file system if inadvertently
change some other program code in the file and then execute it?
 
Donald said:
Thanks for the advice. Suppose I use debug to change the filename,
what are the chances of damaging my file system if inadvertently
change some other program code in the file and then execute it?
Click to expand...

Not very much. But I would try to find an easier tool than debug -
there are free hex editors around on shareware sites, and very difficult
to make serious mistakes with them if just changing one letter in such a
name
 
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