4 Oct
2015
4 Oct
'15
5:27 p.m.
On 2015-10-04 20:09, Henk Gooijen wrote:
Some corrections to my post regarding the console LED
behavior.
Voltage levels on the CPU backplane are still good whne the 2 CPU boards
are installed in the backplane, but the processor is not responsive to
the switches on the console panel.
The RUN LED is on, ADDRESS/DATA are all off. When the HALT/ENABLE switch
is in the HALT position and START is toggled ("reset"), the RUN goes off
and the ADDRESS/DATA LEDs all go on.
LOAD ADDR, EXAM and CONT have no response.
When I set HALT/ENABLE switch to ENABLE and toggle START, the RUN LED
goes on and DATA/ADDRESS LEDs go off, except LED "0".
You mentioned NPR problems before, but I have never seen a broken NPR
signal cause any problems at power on. Broken NPR normally cause DMA to
not work.
However, what you describe sounds exactly how I've seen a lot of
machines behave when the terminator is missing. Check for bus
continuity, and termination.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol