Being safe on the internet (was Re: Here we go again - ISP DPI, but is it interception?)

Paul Leyland paul at
Wed Aug 11 20:19:00 BST 2010

On Wed, 2010-08-11 at 19:52 +0100, ken wrote:

> A colleague of mine could both do hex arithmetic in his head and

I can do hex addition, subtraction and simple multiplication in my head.
I thought it was a relatively common skill...

> read 360/370 machine code from dumps and at least once confused 
> the people who took problem calls at IBM by telling them exactly 
> what the programmers had done wrong in the source code of a 
> program for which we didn't have the source code - the error was 
> produced by an obvious typo in the assembler. Obvious to him 
> that is. Not me.

Reminds me when I was a sysadmin at Oxford and we had one of the first
DEC Alpha systems in the country.  The other sysadmin (Malcolm Beattie)
and I told DEC support precisely what was wrong with part of the OS (I
forget what it was called in those days.  Alpha OSF/1 perhaps?) by
looking at the hex dump and providing them with two snippets of C, one
containing the error and another with a fix.  We didn't have source so
could only use the variable names which were present in the symbol table
and had to invent the others.  It was after that episode that DEC
started taking us seriously and let us talk directly to the dev teams
instead of having to go through multiple layers of tech support.

Happy days, though also very stressful days..


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