VAXen at home

Tony Duell ard at p850ug1.demon.co.uk
Thu Oct 18 14:42:35 CDT 2007


[VAX 11/730 IDC]
> > Can you use an RL01, I wonder. No idea why you'd wnat to, but the manuals
> > don't say one way or the other, so I am curious.
> 
> Good question.  Back in the day, I owned RL01 drives (since they were
> under $200 and RL02s at the time were over $1000), but we never had
> RL01s where we used VAXen.  ISTR there was something about being able
> to use RL02s but not RL01s with the RL278 interface on a DECmate I,
> but I also have not had the chance to explore that, either.

It's got to be a software.driver issue I think. From waht I rememebr of 
the RL's. the only difference between the RL01 and the RL02 is that the 
latter has twice as many cylinders. Since the cylinder offset (how far to 
move) is sent serially on a seek command, and since in both cases, the 
command (including the offset) is a 16 bit number, there's no hardware 
difference that I can think of at the interface. The data rate is the 
same, too.

I don;t see how you can make hardware that works with the '02 and not the 
'01 unless you're delibrately trying to do so (and have it, say, read out 
the drive satus, detct the 'I'm an RL02' bit and shut down if it sees an RL01
> > I find it impressive that you can build _any_ VAX using standard chips
> > (OK, with some PALs, and the memory ECC gate arrays from an 11/750 (I
> > think), but the latter are hardly an important part of the CPU) on 3
> > hex-height DEC boards.
> 
> I was pretty impressed when I saw the guts of an 11/750 for the first
> time - it was so much smaller than an 11/780.  I, too, was impressed
> when I saw all of that essential functionality in an 11/730.  My first
> MicroVAX was even more amazing, but that's another product line and
> another topic.

I guess I'm less impreessed when I see large LSI chip, simply because I 
don't have an intuitive idea for how much you can do in one at a given 
date. But having used TTL (and PALs) a lot, I do haev an indea of what 
those sort of chips can do, which makes the 11/730 very impressive to me. 
(And for a slightly different reasons, the HP9830...)

-tony



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