22 Apr
1998
22 Apr
'98
2:30 p.m.
It was thus said that the Great Max Eskin once stated:
But, since Alphas must share SOMETHING in common with the PDP-11,
I think the PDP-11 has only three things in common with the Alpha:
D E C
Other than that ... 8-)
wouldn't it be possible to write a normal program
for the Alpha,
running under NT or Linux, that would give PDP emulation at P-II-like
performance?
If the PDP-11 is anything like the VAX in terms of instruction space, it
might be possible. The only hitch is unaligned reads/writes to memory (I'm
not sure if the Alpha supports this. If not, that right there is a critical
performance hit). I'd probably start in C (so that it could be ported to
other systems) and then find the hot spots and recode those in assembly 8-)
Now, making a VAX that would do that is a bit more
interesting, though
probably already done. VAX is much more useful these days than PDP-11.
I don't think so. The current trend in CPU design in away from complex
instruction sets (which is something the VAX is) and more towards simplified
instructions sets with same sized instructions. And the cutting edge is
multiple instructions per word (which only proves we've come around again to
the CDC series)
More on this subject: I have long thought that some
computers that
are now mostly PD, like the C-64, should be rebuilt in kit form and
sold to kids for $20 each. Now THAT would be nice. Oh, and make them
make their own kernel, and hold a contest for the best one. The
winner gets an emulated PDP-11.
Check bask issues of Byte (pre '88 - your local library or university
library might have them). Full schematics for a slew of computers (mostly
from Steve Ciarcia) and in the Sep/Oct '85 issues
the schematic for a CPU.
Ah, if only I had the time and equipment ...
-spc (Have compiler, will code ... )