pyramid architectural restraints
Wm Leler
wm at tekchips.UUCP
Fri Apr 27 04:48:48 AEST 1984
1- I have heard Dr. Fred Brooks state that it was a mistake
to allow non-aligned word accesses in the IBM/370.
2- I don't understand why you must pay a 25% space penalty
to use the Pyramid machine. Maybe rewrite your accessesing
functions, but change your data structures? In the worst
case you could grab everything a byte at a time and assemble.
Not that you should do this, I was just trying to show that a
machine that requires word alignment can do any data structure.
3- <enter sarcasm mode> Well, if you are complaining about
machines that require word alignment, how about all those
machines out there that require *byte* alignment! I want
to be able to store my double precision floating point numbers
starting with any bit in memory I desire! What about the
waste when C programmers use ints (32 bits long!) for boolean
flags? Or all those structures that contain padding? Wouldn't
this solve the problem of structure comparisons? And I know
how many bits wide my integers should be. I should be able
to have 19 bit integers, or 129 bit floats. Foo on alignment.
I mean, you hardware guys are making my job as a software
hacker much harder. Like someone said, making a machine
cheaply at the expense of making software harder to write
is a big lose.
<exit sarcasm mode> :-O :-) ;-)
Please don't send me mail about bit aligned machines. I already
know about them.
Wm Leler 503/627-5151
wm.Tektronix at csnet-relay
{ucbvax|allegra|decvax|ihnp4}!tektronix!wm
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