[Info-vax] Y3K for PDP-11 Operating Systems

[vandys at vsta.org]

In alt.sys.pdp11 Johnny Billquist <bqt at softjar.se> wrote:
> I wouldn't be so sure on string handling, since the VAX have lots of 
> native instructions to deal with that, which the 11/70 do not. Integer 
> on the other hand, yes.

I think it was most competetive when you used multiple of its more optimized
instructions.  For instance, my recollection is that the single-instruction
bulk string ops ran slower than the hand coded move/loop constructs.  (Most
of my time was on 750's and the odd 780, and this no doubt changed as DEC
fleshed out their Vax line.)

> The VAX have a single instruction for that, while the 
> PDP-11 needs to manually handle both processor registers and MMU 
> registers.

Having a single instruction does not mean you have a *fast* single
instruction.  That was definitely the case for bulk string ops.  I don't
recall actual task switch performance; that was not an area which caused
me problems.

-- 
Andy Valencia
Home page: http://www.vsta.org/andy/
To contact me: http://www.vsta.org/contact/andy.html