On Sat, Nov 27, 2010 at 9:04 AM, David Masover <ninja / slaphack.com> wrote:
> On Friday, November 26, 2010 05:51:38 am Phillip Gawlowski wrote:
>> On Fri, Nov 26, 2010 at 1:42 AM, David Masover <ninja / slaphack.com> wrote:
>> > I'm really curious why anyone would go with an IBM mainframe for a
>> > greenfield system, let alone pick EBCDIC when ASCII is fully supported.
>>
>> Because that's how the other applications written on the mainframe the
>> company bought 20, 30, 40 years ago expect their data, and the same
>> code *still runs*.
>
> In other words, not _quite_ greenfield, or at least, a somewhat different
> sense of greenfield.

You don't expect anyone to throw their older mainframes away, do you? ;)

> But I guess that explains why you're on a mainframe at all. Someone put their
> data there 20, 30, 40 years ago, and you need to get at that data, right?

Oh, don't discard mainframes. For a corporation the size of SAP (or
needing SAP software), a mainframe is still the ideal hardware to
manage the enormous databases collected over the years.

And mainframes with vector CPUs are ideal for all sorts of simulations
engineers have to do (like aerodynamics), or weather research.

>> Legacy systems like that have so much money invested in them, with
>> code poorly understood (not necessarily because it's *bad* code, but
>> because the original author has retired 20 years ago),
>
> Which implies bad code, bad documentation, or both. Yes, having the original
> author available tends to make things easier, but I'm not sure I'd know what
> to do with the code I wrote 1 year ago, let alone 20, unless I document the
> hell out of it.

It gets worse 20 years down the line: The techniques used and state of
the art then are forgotten now, for example (nobody uses GOTO, or
should use it, anyway) any more, and error handling is done with
exceptions these days, instead of error codes, for example. And TDD
didn't even *exist* as a technique.

Together with a very, very conservative attitude, changes are
difficult to deal with, if they can be implemented at all.

Assuming the source code still exists, anyway.

-- 
Phillip Gawlowski

Though the folk I have met,
(Ah, how soon!) they forget
When I've moved on to some other place,
There may be one or two,
When I've played and passed through,
Who'll remember my song or my face.