Re: S/390 (was Market pressures for more reliable software)

["Gary Labowitz" <garyl@enter.net>]

And, of course, there was LA *-4 used all the time for base registers on the
fly.
Gary
"robin" <robin_v@bigpond.nospam.com> wrote in message
news:xME_6.9627$e5.27883@newsfeeds.bigpond.com...
> Roedy Green <roedy@mindprod.com> writes: > On Thu, 28 Jun 2001 04:01:02
GMT, robin <robin_v@bigpond.nospam.com>
> > wrote or quoted :
> >
> > >> To load you had to adjust all the
> > >> address references to account for where in RAM the program was
loaded.
> > >
> > >No, only those words that had been specified as containing an absolute
> > >address.
> >
> > you only had a 12 bit displacement, so you needed great many ADCONS
> > (address constants),
>
> I'm aware that the displacement is 12 bits, having used the
> assembley language for many years.
> However, my original post mentioned program-relative addressing
> as one of the modes.  With the BALR instruction, one or
> more registers can be loaded with the absolute address of the next
> instruction.  This register(s) can then be used as the
> base register(s).  No address constants needed.
>
> The number of address constants depends on the programmer.
> There might be none or very few such constants.  Certainly not enough to
> significantly increase program load time.
>
> > to fill your base registers with before you could
> > get at anything. On load, all these had to be adjusted to account for
> > where the program was actually loaded in RAM.
>
> Several instructions, requiring very little execution time.
>
> > Roedy Green, Canadian Mind Products