PDP-11/45 RSTS/E boot problem

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Feb 11 12:03:02 CST 2019

    > From: Jon Elson

    > Likely some disk controllers did NOT SUPPORT crossing 64K boundaries!

No; the RK11 spec says "[the two extended memory bits] make up a two-bit
counter that increments each time the RKBA overflows".

The actual error turns out to be slightly different to my guess; there's
a spurious overflow from the low 16-bit register to these bits at 0170000.

I can see how the diags didn't catch that one! Unless you try a multi-block
xfer that walks across the boundary.... A perfect example of Vonada #12.


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