Massbus - was: Re: VAX 11/750
cz at alembic.crystel.com
Wed Feb 24 11:31:32 CST 2021
> Well, I had a
> program that could examine the home blocks, and I knew where to find the
> backup home blocks. So, I hacked that program to copy the backup block
> to the main one, and then change the checksums to agree.
That is one way to avoid a very long restore :-)
> The other issue is the voice coil could suck dirty air in during long
> seeks, so they had ti replace the HDA and put a filter over the air
> exhaust from the voice coil.
Yes, they had issues. Another one apparently is the heads will glue
themselves to the drive after a few years, I was researching ways to
unstick the heads without damaging them (hint: Never use Isopropyl to
clean a RM03 disk head. It will unglue it and hilarity will result) but
that whole thing was mooted when it vanished.
> MASSBUS was not anything like a UNIBUS, it was a lot closer to an IBM
> channel bus and tag cable.
Ok, however the address and data bus feels a lot like a Unibus. And all
of the registers are in the drive controller/adapters, it almost feels
like you are tickling the adapter directly off the Unibus. Given Dec's
joy with Unibus repeaters, bridges and windows it does feel like a
window into the Unibus itself.
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