On Fri, 5 Mar 2004, Christopher Zach wrote:

> MASSBUSS devices included sequencing circuitry. Basically a serial cable
> that goes from system to system.


Really? I cannot remember any such stuff on any massbus devices that I've
worked with, and that includes RP04, RP05, RP06, RP07, RM02 and RM03,
TU45, TU77 and TU78.

Older MSCP disks have it, however. RA60, RA80, RA81 and RA82 to be
specific. The power sequencing bus is simple, though. Not even serial.
It's just an enable signal that passes through all disks, and a disk is
not allowed to spin up if the signal isn't available. The first disk in
the chain have a "terminator" at the in-socket, to enable it to spin up.

Newer than that instead uses a delayed power control bus.

Johnny

Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt@update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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