PDP-11/45 RSTS/E boot problem
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.
More information about the cctech