vbdos crashing

[simon place]

i've had a confusing vbdos problem for years, but i've been able to find ways
round it until now.

when making executables, they sometimes crash, sometimes after extended
periods, but i've found that making a few small unimportant changes to the
code can result in the executable being ok or crashing differently ( sometimes
memory related basic error messages, sometimes general protection errors,
sometimes lockups or resets? ( under a windows dos box or native dos seems not
to make a difference.))

the problem seems to get worse the larger the program gets, ( 320k presently
but this is well used software with feature creep, ( from which a make a
little money.) ) seems much more reliable in the development environment, but
do get
occasional problems this way, and now i'm also getting different behaviour on
different hardware!

any help much appreciated.

( p.s. have looked at emm problems, driver or windows set-up problems.)

[Dan Barclay]

It's been some time since I've done VBDOS work, but if you can give more
detail maybe someone here can give you better info.

By "crashing" what do you mean? Error messages? Crash address?

There are known problems with VBDOS, particularly if you are using the forms
engine. It was released as a 1.0 product and never even got a patch release
(even though MS folks promised it to us).

From your symptoms, maybe you're running into one of the memory leak
problems. If, for example, you display a modal form (including MsgBox) from
inside a Sub or Function you'll lose a little memory. This memory loss
occurs each time the form is shown. Eventually you will run out of free
memory.

Dan

Post by simon place
i've had a confusing vbdos problem for years, but i've been able to find ways
round it until now.
when making executables, they sometimes crash, sometimes after extended
periods, but i've found that making a few small unimportant changes to the
code can result in the executable being ok or crashing differently ( sometimes
memory related basic error messages, sometimes general protection errors,
sometimes lockups or resets? ( under a windows dos box or native dos seems not
to make a difference.))
the problem seems to get worse the larger the program gets, ( 320k presently
but this is well used software with feature creep, ( from which a make a
little money.) ) seems much more reliable in the development environment, but
do get
occasional problems this way, and now i'm also getting different behaviour on
different hardware!
any help much appreciated.
( p.s. have looked at emm problems, driver or windows set-up problems.)

[simon place]

thanks for the reply,

i found the modal window memory leak during a thought scan of the ms knowledge
base for vbdos, but didn't see any others,

regarding the nature of the crash, i did write;
"memory related basic error messages, sometimes general protection errors,
sometimes lockups or resets? ( under a windows dos box or native dos seems
not to make a difference.))"

but failed to emphasize that these most often occur immediately, or rather
immediately after the main form has been displayed.

Post by Dan Barclay
It's been some time since I've done VBDOS work, but if you can give more
detail maybe someone here can give you better info.
By "crashing" what do you mean? Error messages? Crash address?
There are known problems with VBDOS, particularly if you are using the forms
engine. It was released as a 1.0 product and never even got a patch release
(even though MS folks promised it to us).
From your symptoms, maybe you're running into one of the memory leak
problems. If, for example, you display a modal form (including MsgBox) from
inside a Sub or Function you'll lose a little memory. This memory loss
occurs each time the form is shown. Eventually you will run out of free
memory.
Dan

Post by simon place
i've had a confusing vbdos problem for years, but i've been able to find

ways

Post by simon place
round it until now.
when making executables, they sometimes crash, sometimes after extended
periods, but i've found that making a few small unimportant changes to the
code can result in the executable being ok or crashing differently (

sometimes

Post by simon place
memory related basic error messages, sometimes general protection errors,
sometimes lockups or resets? ( under a windows dos box or native dos seems

not

Post by simon place
to make a difference.))
the problem seems to get worse the larger the program gets, ( 320k

presently

Post by simon place
but this is well used software with feature creep, ( from which a make a
little money.) ) seems much more reliable in the development environment,

but

Post by simon place
do get
occasional problems this way, and now i'm also getting different behaviour

on

Post by simon place
different hardware!
any help much appreciated.
( p.s. have looked at emm problems, driver or windows set-up problems.)

[Dan Barclay]

Memory access errors are difficult to track because they could be set up by
a misqueue well before the error is actually triggered.

One classic cause of memory access errors is simply working outside array
boundaries, string lengths, etc (as opposed to a VBDOS bug). Try compiling
with the /D compiler switch, which should trap these kinds of errors.

If that doesn't catch your problem, you might try tracking the crash
location. In the crashes, does it provide a memory:offset number in the
error message? If so, there is a way you can translate that into a location
in your code.

Dan

Post by simon place
thanks for the reply,
i found the modal window memory leak during a thought scan of the ms knowledge
base for vbdos, but didn't see any others,
regarding the nature of the crash, i did write;
"memory related basic error messages, sometimes general protection errors,
sometimes lockups or resets? ( under a windows dos box or native dos seems
not to make a difference.))"
but failed to emphasize that these most often occur immediately, or rather
immediately after the main form has been displayed.

Post by Dan Barclay
It's been some time since I've done VBDOS work, but if you can give more
detail maybe someone here can give you better info.
By "crashing" what do you mean? Error messages? Crash address?
There are known problems with VBDOS, particularly if you are using the forms
engine. It was released as a 1.0 product and never even got a patch release
(even though MS folks promised it to us).
From your symptoms, maybe you're running into one of the memory leak
problems. If, for example, you display a modal form (including MsgBox) from
inside a Sub or Function you'll lose a little memory. This memory loss
occurs each time the form is shown. Eventually you will run out of free
memory.
Dan

Post by simon place
i've had a confusing vbdos problem for years, but i've been able to find

ways

Post by simon place
round it until now.
when making executables, they sometimes crash, sometimes after extended
periods, but i've found that making a few small unimportant changes to the
code can result in the executable being ok or crashing differently (

sometimes

Post by simon place
memory related basic error messages, sometimes general protection errors,
sometimes lockups or resets? ( under a windows dos box or native dos seems

not

Post by simon place
to make a difference.))
the problem seems to get worse the larger the program gets, ( 320k

presently

Post by simon place
but this is well used software with feature creep, ( from which a make a
little money.) ) seems much more reliable in the development environment,

but

Post by simon place
do get
occasional problems this way, and now i'm also getting different behaviour

on

Post by simon place
different hardware!
any help much appreciated.
( p.s. have looked at emm problems, driver or windows set-up problems.)