23 Oct
2005
23 Oct
'05
2:54 p.m.
Subject: Re: FPGA VAX update
From: woodelf <bfranchuk at jetnet.ab.ca>
Date: Sun, 23 Oct 2005 14:58:39 -0600
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at
classiccmp.org>
Chuck Guzis wrote:
>Slightly OT: How fast (in comparison to the original 11/780) do PC-based
>emulators run? My only close-up exposure with this line was a couple of
>years with an 11/750. It didn't seem like a speed demon then.
>
The 750 was around .6 to .7 a 780 for the cpu however the mass storage
systems for the 780s were more elaborate and faster.
The emulators run alot faster, but the problem is the
11 is still a
commerical product
so I don't think we will get better new hardware out.
70ns was 1982 tech level. Tech for 1995 was 25ns for memory.
Current is under 1ns.
Don't forget one of the features of current hardware is the 1ns/ft
barrier is outside the chip.
Allison
If PC-based emulators are fast enough, why bother
with the IC version? An
intellectual exercise? Or will the FPGA version run an order of magnitude
faster than the original?
I suspect about the same speed as PC's 15 years ago or 74Sxx speeds.
The real speed limit on computers
now days is the cache memory. A external bus depending on memory used
is the factor.
Most common memory is about 120 ns to 70 ns access time unless you want
to use the latest
chips.