Yep, fun times on LSI-11/2! Some configurations also won't boot unless it's
on, if I remember correctly. I suppose this is part of the reason that
LSI-11/2 CPU boards are so cheap!
Thanks,
Jonathan
On Wed, Aug 14, 2019 at 10:17 AM Noel Chiappa via cctalk <
cctalk at classiccmp.org> wrote:
From: Paul
Koning
Isn't the interrupt disabled by RESET?
Nope. On the -11/03 and KDF11-A, BEVNT is wired straight into the CPU, and
there's no internal register to control it.
The BDV11 does have a register which can enable/disable the LTC (it
connects
BEVNT to ground via a transistor when the appropriate register bit is
cleared); but, ironically (given your question), BINIT/RESET does _not_
clear
that register! Only BPOK does. (My theory is they were short of a bus
receiver
for BINIT, and rather than put a whole extra chip on the card...) So, once
on,
it has to be explicitly turned off, or the 'boot' switch (which toggles
BPOK)
has to be hit.
The KDF11-B and all KDJ11 machines do have the LTC register, which operates
'correctly'.
Noel