Re: 6502 illegal opcodes questions

[pausch@saaf.se (Paul Schlyter)]

In article <bruce#fanboy.net-7FEFE6.22195226052006@news.newsreader.com>,
Bruce Tomlin  <bruce#fanboy.net@127.0.0.1> wrote:

> In article <e56rj1$7lo$1@merope.saaf.se>,
>  pausch@saaf.se (Paul Schlyter) wrote:
> 
>> numbers for your number crunching stuff?  Forget about Java then....  or
>> does your hardware have 1-complement signed integers?  Java requires
>> integers to be 2-complement, i.e. you must then have some emulation layer
>> on top of your native integer format - that's inefficient.
> 
> Seriously, has anyone used 1's complement arithmetic in the past 10-20 
> years or so?  And why?

I used a CDC Cyber-720 twenty years ago: it has 60-bit word size,
non-IEEE floating-point format, and one-complement arithmetic - not
only for integer data but for floating-point data as well!  A few
years later that machine was put out of service though.


Btw one could also ask:

"Seriously, has anyone used the Apple II, or some other obsolete 8-bit
micro, in the past 10-20 years?  If so, why?"

...and the surprising (to some) answer is: yes!


There are emulators not just for the Apple II and other past popular
micros.  There are emulators for old mainframes as well - check out:

   https://gna.org/projects/backtolife/

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