On Sun, 24 Oct 1999, Allison J Parent wrote:
> <Looks like the 6500 was about 13 VAX-11/780 MIPS. That would make it about
> <2x to 3x slower than a 486DX2/66.
>
> Not even close. More like a stack of a dozen or more of the 486s. It
If you look at:
http://www.digital.com/timeline/1990-4.htm
It states: "The VAX 6500 processor delivered approximately 13 times the
power of a VAX-11/780 system, per processor."
To me, that means "13 MIPS". 13 MIPS is about 2 to almost 3 times slower
than a 486dx2/66.
But let's take a look at some Dhrystone 2.1 numbers I found:
CPU MIPS MIPS
System OS CPU (MHz) V1.1 V2.1
---------------------- ------------ ----------- ----- ------ ------
VAX 8650 4.3 BSD ----------- 18 6.3 6.2
cc -non_shared -DUNIX -O5 -ifo
80486DX2/66 Linux 2.0.0 80486DX2 66 29.3 26.9
gcc 2.7.2, gcc -DUNIX -O2
80486DX2/66 NetBSD 1.4.1 80486DX2 66 ---- 34.4
egcs -DUNIX -O2
For the Dhrystone 2.1 case, 26.9 / 6.2 = 4.33 --> dx2/66 is 4 1/3 times as
fast as the 8650. (Using the slower Linux numbers, too).
As a sanity check, look at
http://www.digital.com/timeline/1984-3.htm
For the 8600, it states: "The VAX 8600, shown here during assembly, offered
up to 4.2 times the performance of the industry standard VAX-11/780... ".
Therefore, the 8600 was 4.2 MIPS. I can't find Dhrystone 2.1 numbers for
the 8650, but let's be generous, and assume that the 8650 was 1.5x as fast
as the 8600 (because the 785 was 1.5x the 780). That puts the 8650 at
6.3 MIPS, which is in rough agreement with the other Dhrystone number, above.
And, back of the envelope, the 6500 was 2x the 8650.
So, if it is not a typo on
http://www.digital.com/timeline/1990-4.htm
then my original assertion is, indeed, correct: The 6500 is 2x to 3x slower
than a dx2/66. ( And the vax 6000-530 is even slower. )
I don't know what it is about collectors that somehow confuses their
memories of the past; maybe their internal core memories have suffered some
bit flips? ;-) (I have some old junk, too, so I consider myself in the
same camp...)
Fact is, these old machines were slow, noisy, hot, power-guzzling behemouths
compared with what we have today.
> usually ran between 30-50 VT1200 Xwindows type terminals under VMS 5.5
> plus the usual batch load and plain terminal user base.
As you know, the vax would run the X -client- which, of course, is not
much of a load. And as for running 50 users, heck, at the VCF 3.0 there
was a guy showing an 8080 running timesharing on a bunch of terminals!
Therefore, to me, you have to measure the performance in some repeatable
way. Dhrystone is not the perfect benchmark (which is close to an oxymoron
anyway), but it is -a- benchmark for integer CPU performance.
> for any IO despite the SCSI, could not multitask well and was known for
> crashing (w3.11) something uncommon the VAX world.
It's too bad that you had to run w3.11; I'm assuming you're running a real
OS on the dx2/66.
> Apples and oranges, the VAX especially the bigger models with the CI and
> other high perf IO busses can easily pound PCI pentiums into the ground
> for shear load.
Now, let's talk about busses. Just how fast -was- this CI? Let's compare
that with 66 MHz 64-bit PCI, which has 66e6 x 64 = 4,224,000,000 bits/sec
peak throughput. What was CI's throughput?
> Allison
-Mike Cheponis
Received on Sun Oct 24 1999 - 14:44:43 BST