Don Maslin/Archiving system software

[Chuck Guzis]

On 18 Mar 2007 at 22:46, Lyle Bickley wrote:

>> There are many, many cases where software written for DOS, Windows 
3.1x, early 
> versions of BSD, etc., will NOT run on high speed systems with more "modern" 
> OSs (XP, Linux, Solaris, etc.).

Lyle, that's not what I said.  I said "a computer from today can run 
software written 40 years ago--and generally, much faster."   I said 
nothing about running under one OS or another. 

To say that running older software on newer machines isn't possible 
is pretty much equivalent to saying that a new machine isn't Turing-
complete.  I can emulate (with whatever software necessary) cycle-for-
cycle operation of an older machine.  Maybe not as fast as the 
original (depending on the complexity of the emulation)--which is why 
I added "generally much faster".

I can readily appreciate that I/O devices may well represent a really 
tough nut to crack, but given a free reign on abstraction, it can 
probably be done in some fashion (e.g. a disk file instead of a tape 
file).

And the reverse is quite true.  I can emulate an IA64 architecture on 
a 2MHz Z80, given sufficient storage and time.  Not fast (or cheap), 
but I can do the emulation.  To say that it's not possible would 
again be equvalent to saying that the Z80 isn't Turing-complete.

Cheers,
Chuck