18 Oct
2007
18 Oct
'07
12:42 p.m.
[VAX 11/730 IDC]
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 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
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. 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.