[Info-vax] Microsoft: Alpha architecture responsible for poor Windows file compression

[David Froble]

Simon Clubley wrote:
> According to:
> 
> http://www.theregister.co.uk/2016/11/02/ghost_of_dec_alpha_sees_microsoft_dumb_down_windows_file_compression/
> 
> Microsoft are saying that limits in the Alpha architecture are responsible
> for poor Windows file compression in today's world. Sample quote:
> 
> |Chen says one of his "now-retired colleagues worked on real-time compression,
> |and he told me that the Alpha AXP processor was very weak on bit-twiddling
> |instructions. For the algorithm that was ultimately chosen, the smallest unit
> |of encoding in the compressed stream was the nibble; anything smaller would
> |slow things down by too much. This severely hampers your ability to get good
> |compression ratios."
> 
> Do any Alpha architecture experts here know if this is the full story ?
> 
> Simon.
> 

Alpha EV4 did not have the WORD and BYTE instructions, thus working on such was 
not efficient.  My understanding is that EV5 added the WORD and BYTE 
instructions, and did much better.  Don't know what might have been added in EV6.

As for "bit-twiddling", don't have a clue.

Keep in mind, Alpha was designed to be very fast and simple.  Some things aren't 
so simple.