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Re: New Vax - future directions :-)
Den 2021-07-06 kl. 16:49, skrev Johnny Billquist:
I was thinking of the new extended Vax :-) The "old one" is not much to
On 2021-07-06 15:24, Anders Magnusson wrote:
Den 2021-07-06 kl. 11:48, skrev Johnny Billquist:
Well, nothing stops from allowing numbers strings in the future. They
are handled like the string instructions, so they can be interrupted.
The same with the other string instructions, no reason to have a
limit on the string length.
On 2021-07-06 11:28, Anders Magnusson wrote:
A side note: There is a very interesting part of the instruction
set that I think should be investigated more - the packed decimal
Those will in fact implement arbitrary precision in hardware, which
could be really nice to have when doing things like crypto
That's an interesting view. I've always looked at the packed decimal
stuff as mostly targeted at Cobol and financial applications.
You need to remember, though, that packed decimal strings have at
most 31 digits. So not entirely arbitrary. (Hmm, not entirely sure
if it is 31 digits, or 31 bytes...)
Very true. But the VAX have defined that you get an exception if the
length is more than 31. So you'd have to break compatibility at least
slightly for this.
Less inefficient than doing arbitrary precision using assembler. The
same as the other string instructions, quite efficient in microassembler :-)
But I also wonder if these instructions are rather inefficient. Good
for financials though, since you're more interested in not getting the
artifacts of floating point in there. And dealing with 31 digits for
money seems plenty enough. Even if we have microcents.
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