PDP-11/45 RSTS/E boot problem

Noel Chiappa jnc at mercury.lcs.mit.edu
Tue Jan 1 20:43:30 CST 2019


    > From: Paul Koning

    >> I haven't sat down with -C and -D manuals and done a bit-by-bit
    >> compare. I just did that (I used the "RK11-C Moving Head Disk Drive
    >> Controller Manual", DEC-11-HRKA-D, and the 1976 "Peripherals Handbook"),
    >> and found in the following:
    >> In the RKDS: bit 7 has changed the definition slightly ("Drive Ready"
    >> to "R/W/S Ready"), but seems to be basically the same.

    > You mean bit 6?  Bit 7 is "drive ready" in both.

@*#$@*$%@&*!!!!! My silverfishionado nature screwed me! I didn't have an
RK11-D manual in paper, so I relied on the "Peripherals Handbook" - and it's
got an error!

In both the 1975 and 1976 edition, the _diagram_ for the RKDS shows bit 7 as
"R/W/S Ready", and bit 6 as "Access ready", but the _table_ shows bit 7 as
"Drive Ready", and bit 6 as "R/W/S Ready"! OK, so let me ditch that, since
it's self-contradictory, and thefore necessarily erroneous.

I'll switch to the RK11-D User's Manual, EK-RK11D-OP-001. It gives bit 7 as
"Drive Ready", and bit 6 as "R/W/S Ready". (The RK11-C manual gave bit 7 as
"Drive Ready", and bit 6 as "Access Ready".)

    > Bit 6 has a different name in the two descriptions but the meaning
    > appears to be the same.

Yup.


Thanks for catching that for me!

       Noel


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