[Info-vax] VMS Software Q1 '23 Update

[Arne Vajhøj]

On 1/29/2023 11:16 PM, Dave Froble wrote:
> On 1/29/2023 7:17 PM, Arne Vajhøj wrote:
>> The Alpha architecture manual says that it only
>> supports:
>> - load D from memory
>> - convert from D to G
>> - do G math
>> - convert back from G to D
>> - store D in memory
>> which sort of operate on D float but loose 3 bits precision.
> 
> Correct, that is how it's provided.
> 
>> The alternative is software emulation, which will be able to do VAX
>> compatible D math but at a speed cost.
> 
> Would you think it would do better than the loss of the 3 bits?  Not an 
> issue most of the time.  However,  I'm aware of a few instances where 
> things aren't so good.  I seem to recall the 5.9 to 6.0 range having an 
> issue.

I wonder what Basic on Itanium does and what Basic on x86-64 does / will do.

Convert to T and do T math? Or software emulation?

> But, it was rather nice to move massive amounts of data from a VAX and 
> have it "just work" on Alpha.

VMS got a pretty good track record for not breaking things.

Hoff would say *too* good a  track record, but ...

Arne