<> bus such as PCI to get peripherals.  If Compaq were to make a new VAX, yo
<> can be use it would be PCI based with no ISA.  
<
< yeah, as i said in my previous post. Qbus is not very fast. 
<Like Matt also pointed out, being asynchronous, you cant preserve 
<compatibility with the old Qbus devices and still speed things up much. 

Really wrong.  Because it's async each card runs at it's speed based on the 
request->acknoledge protocal of the bus.  That means you can have really 
slow cards mixed with fast ones and each will run at IT'S maximum speed.
The max speed of qbus is much higher than 3mb, since transfers can be 
16bit and a fast cycle is down well under 500ns we are already at 4mb/s
with real DEC cards available every day.  It can go a quite a bit faster
if you shorten some of the setup and hold times.  However if you do that
the ide of using 9201s an BCnn cables to expand the bis to several more 
boxes will be questionable.  however if done using modern parts the bus 
can easily hit 25-40mb/s and that is disk speed.

Then again, I defy someone to build a PCI bus or turbo channel with 18 
slots!

<> Q-Bus is asynchronous bus.  There is little or no timing.  That makes it
<> hard to speed up.

Not true.  it can be much faster but DEC specs for setup and hold times
are a limiting factor.  It's protocal, but, they guarentee ANY card works.

The key thing is it's only 16bit data path and VAX is 32bits.  A 32bit 
wide bus like PCI or turbo is a better plan and you can still bridge to 
qbus for old device support.

What make more sense and even DEC did this, for low cost and good speed
put it all on one card like the 3100 family did.  Cut the chip count
and cut the cost.

What I really hate is applying todays PC design rules and standards to VAX 
and PDP-11 machine that are typically 5-10 years older.  One only needs to 
look at PCs contemporary to those DEC systems to to see it's the PC that 
was lagging.  PCs seriously didn't start to pass vaxen until the Pentiums 
were clocking over 100mhz.  The problem is PCs still crash no matter what,
though Netbsd, freebsd or linux is better but they can't make up for 
flakey hardware.  When Linux was new, VAXen standard for performance was
24x365 and often down time was atrtributed to power failures.  Why, 
conservitive design rules and yes even them slow busses that really 
worked without adding errors.

I know I'm singing to the choir.

Allison