[Info-vax] OT: obscure PDP11 OSes (even more dinosaury)

[Paul Sture]

On 2015-06-16, Bob Koehler <koehler at eisner.nospam.decuserve.org> wrote:
> In article <mlouja$7aj$2 at dont-email.me>,
> Simon Clubley <clubley at remove_me.eisner.decus.org-Earth.UFP> writes:
>> 
>> The TKB overlay functionality (and it's associated documentation) is
>> something I have _very_ gladly left in the past and have almost
>> successfully purged from my memory. :-)
>
>    Before I worked with TKB overlays, I worked with IBM OS 360 overlays.
>    Same concept, more difficult implementation.
>
>    Upgrading from an 11/34 to an 11/44 allowed us to move from disk
>    redident to memory resident overlays.  Just a small detail in the
>    overlay information, but such an improvement in performance.

Our break came when RT-11 got extended memory management and we could
upgrade to something like 192K RAM.  Apart from supporting extra users I
could modify the overlays so that the main processing loop the order
entry programs had weren't overlaid against each other.

The programs had started out life looking something like this:

    call a  ; get and validate user input
    call b  ; update the files

where modules "a" and "b" were overlaid against each other.

-- 
I don't know what the language of the year 2000 will look like, but I
know it will be called Fortran.                    -- Tony Hoare 1982