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From: risto@tuura.UUCP (Risto Lankinen)
Newsgroups: comp.windows.ms
Subject: Re: what causes 'unrecoverable error'?
Message-ID: <951@tuura.UUCP>
Date: 23 Jan 91 13:35:16 GMT
References: <UbZZ8Ny00WB4M20V8m@andrew.cmu.edu> <21616@neptune.inf.ethz.ch>
Organization: Nokia Data Systems Oy
Lines: 43

brandis@inf.ethz.ch (Marc Brandis) writes:

>In article <UbZZ8Ny00WB4M20V8m@andrew.cmu.edu> hp0p+@andrew.cmu.edu (Hokkun Pang) writes:
>>are there any usual causes of the 'unrecoverable error'? I ...

>{explanation of UAE deleted}

>Interesting how many professional programs have lots of such bugs in them. 
>You can imagine that they were also there in the real mode times of Windows
>(1.0 - 2.13), but there they were not detected but rather modified the data
>or code belonging to other programs, causing all kind of mysterious problems
>later. -:)

Hi!

Sometimes so, indeed.  But given that the applications often work just about
right in older Windows, the bugs that pass (more or less dense) debug-phase
sieve could almost always be considered 'harmless'.

For example:
   - Writing the NULL character (required for C string) one past the end of
     the buffer reserved for it
   - Initializing arrays with wrong index range (1..N instead of 0..N-1)
   - having private class/window data without proper extra space reserved
     from the end of the structure
   - Deliberately accessing devices directly to boost performance or to use
     non-supported hardware

In many cases, the 'off-by-one' errors either hit the program's own data or
the otherwise unused 'granulation gaps' between memory blocks, that normally
are allocated only at certain even boundaries.  Windows 3.0 traps these, but
the older versions don't.

I'm *not* writing to encourage bad coding manners, but to suggest that even
though some programs seem to behave badly in Windows 3.0 doesn't necessarily
cast doubt to their reliability using with earlier versions of Windows.

Terveisin: Risto Lankinen
-- 
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