In <[EMAIL PROTECTED]>, on 09/10/2006
at 01:04 PM, Paul Gilmartin <[EMAIL PROTECTED]> said:
>Didn't such tagging extend to data types, fixed vs. floating, so an
>attempt to perform a floating point operation on a fixed point field
>was detected as an error?
For the B6500 and descendants in distinguished among, e.g., single
precision, double precision, code and various types of descriptors.
For the RCA 601 it was whatever the programmer used it for, although
there were some OS conventions.
>Requires a paradigm shift
Much more than just that required by the tagging. The B6500
instruction set didn't support directly accessing storage; you could
address data in the stack and you could access data via descriptors.
Indexing into array descriptors included an automatic bounds check.
>I believe such machines also had hardware array subscript
>calculation,
Multidimensional arrays were handled as arrays of array descriptors.
>And I of know one regular contributor to this list who has strongly
>opposed the "nanny language" concepts of enforcing type conformity
>and array bounds on programmers.
I'd probably disagree with him, depending on how he worded it.
--
Shmuel (Seymour J.) Metz, SysProg and JOAT
ISO position; see <http://patriot.net/~shmuel/resume/brief.html>
We don't care. We don't have to care, we're Congress.
(S877: The Shut up and Eat Your spam act of 2003)
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