Power Supply, Memory, Crashes

I don't have the time to post all the details before going to sleep, but I did a few things tonight including measure the power supply voltages, install new RAM, and have a lot of problems and crashes.

XL1201 Power Supply Voltages

I tested the voltages of the XL1201 power supply with a Fluke 269 multimeter and a Rigol DS1000E, while the system was on and sitting at the FEP command prompt.

  • The big 5V rails are putting out 5.13V per the Fluke
  • There is a -5V rail that is putting out -5.25V per the Fluke
  • The 12V rail is putting out 12.02V per the Fluke
  • The -12V rail is putting out -12.03V per the Fluke
  • There's about a 8mV average ripple at about a 10 microsecond frequency on the 5V rail, but the non-average is more like an 85mV ripple
  • The 12V rail has about a 94mV ripple with a complex waveform but it seems more like a 3 microsecond frequency

12V Rail 5V Rail

New Memory

I received two 4 Mword memory cards from [David K. Schmidt] a few weeks ago. I finally installed them, and while at it I took detailed pictures of the whole XL1201 that I will post.

I put the whole thing back together and made sure everything was tightly seated with a rubber mallet and a small wood block. The computer booted just fine.


Unfortunately, at boot, only 6 Mwords of memory were seen. Self-test of the memory seems fine. I may have seen some signs of possible physical damage of the Merlin II under the second memory card slot, so I'll have to look more closely at that when I load the macro photos. The I333-tests.flod FEP overlay contained some memory tests which I ran that didn't seem to show any test problems.

Simple Memory Test Full Memory Test

XL1201 Problems

With all this done, the XL1201 just hasn't been reliable. It crashed several times tonight already, and several times earlier today. I hoped new RAM would help, but obviously it didn't. The only other difference of note is that I hooked a serial cable up to the console.

For the final coup-de-grĂ¢ce I just power-off cold booted the XL1201 and let it sit there. After a while I glanced at the screen and noticed it had self-booted. Worse, the FEP wouldn't even do anything and immediately showed an error when its autoboot.boot sequence started. An earlier error dumped me into FEP and I tried the c-b suggested by Kalman Reti to get a short backtrace but it literally crashed again while showing the backtrace! (Thank you for your help, by the way!)

Error 1 Error 2

Autoboot error after it was just sitting there:

Error 3

Anyway, after I unplugged the Serial Port and booted (and just let it sit at the Genera banner), no such luck. It decided to self-reboot and gave me that same exact error:

[Error: Error trap #o-7757370330; 37000055734 at #<DTP-ODD-PC (5 in NIL) 37000027242>]
FEP Command:  

Douglas Fields

Writing LISP and Haskell since 1990