[Info-vax] OpenVMS.Org quick pool

[BillPedersen]

On Wednesday, August 22, 2012 8:23:26 PM UTC-4, Richard B. Gilbert wrote:
> On 8/22/2012 3:39 PM, David Froble wrote:
> 
> > Single Stage to Orbit wrote:
> 
> >> On Tue, 2012-08-21 at 15:10 -0400, Stephen Hoffman wrote:
> 
> >>>> 32 bit is limited to a maximum of 4GB. One won't be able to do a lot
> 
> >>>> with that with today's software requirements.
> 
> >>> TKB
> 
> >>
> 
> >> WTF is TKB?
> 
> >
> 
> > Don't ask, if you find out, it will ruin your life ..
> 
> 
> 
> I finally recalled TKB!  Many long hours waiting for the Task Builder!
> 
> I don't miss it!!!!

Task builder was the key to using the 64KB address space in most of the PDP-11 environment.  Yes, there were various versions to solve problems, such as the SLOTKB to help when the overlay structure became too complex.  But if you wanted to have the application run on a PDP-11 - and for many that was the only choice then TKB became your friend and enemy.

ODL - Overlay Descriptor Language define the structure of the overlays.

In some very complex programs it was not uncommon to have a half dozen or more overlay trees each with branches, many with replicate routines as they were needed in each overlay but could not be kept in the root as that took up too much of the address space for some other branch which did not necessarily need that routine.

RSX-11M, RSX-11D, IAS, RSTS/E (RSX subsystem), VMS (RSX subsystem) and POS-11 used this mechanism.  RT-11 used a different mechanism but similar.  I did a bit of RT programming but not too much.  I did a LOT of RSX and IAS as well as VMS later...

ODL was the start but not the finish to the problem.  Since you had a restricted address space you had to then use the disk more to facilitate things like virtual arrays (which eventually showed up in Fortran).  Or more common things of working with data sequentially - which had been done for many years in the past before PDP-11s.

Yes we have come a long way. And YES, we need to keep going.

I think it is great the COV and other forums exist where we can discuss these topics - both historical and current.

Keep it up!

Bill.