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11/45 RSTS boot problem

fritzm

Experienced Member
Joined
Dec 11, 2011
Messages
142
Location
Oakland, CA
Hi all,

Some here may know I’ve been working on an 11/45 restoration off and on for some time now. My ’45 currently has floating point, KT11-C mem mgmt, 124 kword MS11-L, and an RK11-C with one restored RK05 drive.

Last week I decided to see if I could bring up RSTS on the machine. I managed to sysgen a minimal V06C system that can run off a single RK05 pack under simh, but when I transfer that image to the real hardware using pdp11gui it does not seem to completely/successfully boot.

The “Option:” boot loader comes up and sub-commands there seem to be working (in particular, the “HARDWARE” sub command shows correctly detected hardware and options). When booting RSTS, after supplying date and time, the idle pattern starts on the front panel (but just the bottom part, on the data lights). When console is in display register mode, it shows an increasing count. Console input is echo’d, but the INIT banner and subsequent prompts are never printed and the read light on the RK05 flickers continuously as if the system is trying to read the same sector over and over.

Figured I’d ping here in case this is a known failure mode to folks more familiar with RSTS? Otherwise I’ll have to dig in single stepping, ’scope fault and interrupt lines, etc... (FWIW, the machine is passing all MAINDEC CPU, MMU, FP, and RK11 diagnostics.)

Cheers, all!
—FritzM.
 
Just one thing come to my mind. But it is just a guess. Once I tried to boot RSX on a machine with BEVNT disabled through a front panel switch. The machine behaved very strangley until I toggled that switch. So maybe it can be something with BEVNT or KW11 or M7856 board?
 
Ah, thanks much Mattis, good suggestion! The machine had previously passed MAINDEC ZKWA, but I hadn't checked it since taking it out to VCF West and back earlier this year. Ran that diagnostic again, and something there does indeed seem fishy, so I'll dig in there...
 
Well, reseated the M787 line clock module, and am passing diagnostic ZKWA now, bit still no joy (same behavior described below) :-/

Also passing the full suite of CPU, MMU, FPU, and both RK11 static and dynamic tests. MS11 diagnostic is a little wonky, so maybe I’ll dig in on that after Christmas. Will have this problem dancing in my head instead of sugarplums I guess until then! :)
 
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