On 2014-01-22 08:16, Christian Gauger-Cosgrove wrote:
Hello:

I've noticed an odd issue. When booting the aforementioned baseline
RSX-11/M+ disk, with 256K of memory, RSX-11 doesn't have enough RAM to
work when it tries to run the startup script. This happens as the
system doesn't have enough memory to allocate a checkpoint space; so
RSX-11 gets stuck in an infinite loop repeating:
<TIME>  *** GEN    Checkpoint space allocation failure
Where <TIME> is the current time in HH:MM:SS format. The CPU is
working, as you can see the time field counting properly. However, the
simulator completely locks up otherwise; you can't Ctrl+E to the sim>
prompt, you can't Ctrl+C or Ctrl+Z the program within RSX-11 itself.

Sounds like a problem in simh, yes.

But just to clarify one thing with RSX here. The problem is not about not having enough memory to allocate a checkpoint space. What the error means is that RSX do not have a checkpoint space. Checkpoint space is the RSX term for disk space used to swap out running tasks to, in order to free memory.

But yes, the basic problem is that you have too little memory. The startup script will setup a checkpoint space for you, but you don't even make it that far... The basic tasks activated at startup is already requiring more memory than you have.

        Johnny

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