Re: Oops (Concertina II Going Around in Circles)

In article <be3r3jhr1kf9n1cdsbik5ejsuso7c3pmmk@4ax.com>,
quadibloc@servername.invalid (John Savard) wrote:

On Fri, 10 May 2024 00:19 +0100 (BST), jgd@cix.co.uk (John Dallman)
wrote:
 

Not that justified the costs of implementing such a huge
instruction set.

 
Well, having a huge instruction set defined and implementing all of
it are two different things.
 
Look at x86, how MMX got replaced by SSE which got replaced by AVX.
 
So if one is going to include instructions that will later become
obsolete, and be replaced by other instructions, not re-using the
same opcodes helps with upwards compatibility.

Intel did not re-use the opcodes. MMX, SSE, SSE2 and so on are all still
implemented and usable. Once a hardware feature has been used in software,
getting rid of it is hard. I'm still building x86-32 software for SSE2
because AVX[2] doesn't do anything useful for it.

John