Re: Super-H machine language issues

[Marcus Comstedt <marcus%mc.pp.se@localhost>]

der Mouse <mouse%Rodents-Montreal.ORG@localhost> writes:

> > If PR is 1, SZ must be set to 0, but [it's effectively forced to 1]
>
> Is this documented anywhere?  I just went through every place where the
> string "SZ" occurs in pdftotext output on that PDF and none of them
> mention this as far as I can see.  (Where did you learn it, for
> example?)

That SZ must be set to 0 when PR is 1 is documented on page 19, which
describes FPSCR, and again on page 123.  That FMOV is 64-bit when PR=1
follows from the general principle that operands are double precision
in this mode, I guess.


> Page 283, describing FSQRT, says the PR=1 version of FSQRT is encoded
> as 1111nnnn01101101, in sharp contrast to the way most PR=1
> instructions use only three bits for a register number, forcing the low
> bit (usually to 0, occasionally to 1).  Is this a typo, and it should
> really be 1111nnn001101101, or is this an exception to the usual
> pairing of registers when doing double-precision floating-point?

Table 7.10, on page 146, says that the format is 1111nnn001101101,
as you guessed, so it looks like a cut'n'paste typo on p283.


  // Marcus