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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